TRADITIONAL POSTERS
 

Vascular Compliance

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                   906.       In Vivo Transit Time MR-Measurements of Pulse Wave Velocity in the Murine Aorta at 17.6 Tesla

Marco Parczyk1, Volker Herold1, Gert Klug1, Thomas Schulze-Till1, Wolfgang Bauer1, Eberhard Rommel1, Peter Jakob1

1University of Wuerzburg, Wuerzburg, Germany

Aortic stiffness increases in an early state of arteriosclerosis, assessable by pulse wave velocity (PWV) MR-measurements. Up to now only studies in larger animals and humans have been reported in literature. The feasibility of in vivo PWV MR-measurements by two non-invasive MR-imaging techniques is presented. Because pulse wave and flow velocities are similar to velocities in humans, but dimensions are about 20-times smaller, the challenges in this project were especially the high temporal and spatial resolutions needed.

                  907.       In Vivo Measurement of Local Pulse-Wave Velocity in Mice with MRI at 17.6 T

Volker Herold1, Gert Klug1, Marco Parczyk1, Christian Ziener1, Thomas Weber1, Susanta Sarkar2, Wolfgang Rudof Bauer1, Eberhard Rommel1, Peter Michael Jakob1

1University of Wuerzburg, Wuerzburg, Germany; 2GlaxoSmithKline (GSK), King of Prussia, Pennsylvania, USA

Pulse wave velocity (PWV) is an important parameter for the evaluation of the arterial stiffness and cardiovascular risk. Several diseases such as hypertension and arteriosclerosis are associated with vascular remodeling and arterial stiffening. Mouse models of human diseases are increasingly used to investigate patho-physiological mechanisms of the cardiovascular system. A non invasive method is presented to assess local PWV in the ascending and descending aorta of mice with MR-Microscopy at 17.6 T. The results demonstrated the feasibility of high field MR microscopy to quantify local pulse wave velocity as a measure of local aortic stiffness.

                  908.       Carotid Wall Shear Rate Measured with Spiral Fourier Velocity Encoding

Joao Luiz Azevedo de Carvalho1, Jon Fredrik Nielsen1, Krishna S. Nayak1

1University of Southern California, Los Angeles, California , USA

Fourier velocity encoding (FVE) has been proposed as a method for non-invasively measuring fluid shear rate and hence vascular wall shear stress, an important factor implicated in atherogenesis. The scan-time of 2DFT FVE is prohibitively long for clinical use, but the recently introduced spiral FVE method shows promise as it is substantially faster. In this work, we investigate the feasibility of using spiral FVE for estimating shear rates near the carotid artery walls in clinically practical scan times. We present: (1) a phantom validation of spiral FVE against high-resolution 2DFT phase contrast; (2) evaluation of resolution requirements; (3) in vivo demonstration.

                  909.       Intracranial Compliance and Pressure Measurement Based on MR Flow Quantification and Brain
                                Circulation Model Circuit: Sensitivity to Hyperventilation and Hydrocephalus

Kagayaki Kuroda1, Kosuke Maruhashi1, Moyuru Ohya1, Masatoshi Honda2, Hideki Atsumi3, Koichi Oshio4, Mitsunori Matsumae3

1Tokai University, Hiratsuka, Japan; 2Tokai University Hospital, Isehara, Japan; 3Tokai University, Isehara, Japan; 4Keio University, Shinanomachi, Japan

A noninvasive technique to evaluate brain compliance index (BCI) and intracranical pressure index (ICPI) based on MR flow quantification and an inverse analysis of brain-circulation-equivalent electrical circuits was developed. The technique was applied to healthy volunteers (N = 6) with normal breathing and hyperventilation during scanning. The BCI significantly decrease with hyperventilation in 5 volunteers. The technique was also applied to patients (N = 3) with hydrocephalus. Both BCI and ICPI were significantly lower in those patients than in the normal volunteers. These results indicated that the technique is sensitive to the change or abnormality of the brain physical properties.

                  910.       Compliance and Anatomy of the Neo-Aorta in Children with Hypoplastic Left Heart Syndrome (HLHS)

Michael Helle1, 2, Inga Voges1, Michael Jerosch-Herold2, Christopher Hart1, Traudel Hansen1, Hans-Heiner Kramer1, Carsten Rickers1

1Christian-Albrechts-Universität, Kiel, Germany; 2Brigham & Women's Hospital, Boston, USA

The purpose of this study was to assess aortic anatomy and aortic compliance (AC) in children with hypoplastic left heart syndrome (HLHS) using cardiac MRI at 3 Tesla.Cine MRI and contrast enhanced time-resolved MR-angiography were performed in all patients for measuring selected diameters of the neo-aorta and for a selected determination of the AC.Diameters of the aortic root, the ascending aorta and the aortic arch were significantly increased. We found a significant smaller aortic isthmus in children with HLHS, whereas the dimensions of the descending aorta were not significantly changed. AC was decreased in the ascending aorta as well as the aortic arch.

                   911.       Quantitative 2D and 3D Phase Contrast MRI: Optimized Analysis of Blood Flow and Vessel Wall
                                  Parameters

Aurélien F. Stalder1, Max F. Russe1, Alex Frydrychowicz1, Jelena Bock1, Jürgen Hennig1, Michael Markl1

1University Hospital Freiburg, Freiburg, Germany

The purpose of this work was the development of an optimized quantitative analysis method in order to derive flow and wall parameters from CINE phase contrast (PC) MR data. The data analysis strategy combines “Green’s theorem” and B-spline interpolation with their finite difference property to provide an optimal quantification of several blood flow and vessel wall parameters. Calculation of the local blood flow velocity derivatives onto the vessel contour using B-spline interpolation allowed a direct and reliable estimate of time-resolved segmental WSS vectors independent of any restrictive global assumptions regarding the flow profile.

 

Vessel Wall Imaging

Hall D                                   Monday 14:00-16:00                                                                                                                                

                 946.       The Effect of Lipid Core Position on Carotid Fibrous Cap Stress Levels

Samuel Alberg Kock1, Jens Vinge Nygaard, Anders K. Niemann1, Anette Klærke, William Paaske, Erling Falk, Won Yong Kim1

1Aarhus University Hospital Skejby, Aarhus N, Denmark

To determine if not only the size of atherosclerotic lipid cores, but also their position influence carotid fibrous cap stress levels, three computational models of a carotid bifurcation with varying lipid core placement were created using geometry based on MRI scans of a patient with a high-grade stenosis. Computational fluid structure interaction simulations were performed on the models revealing proximally based lipid cores to exhibit far greater stress levels than both distally and centrally located lipid cores. Computational analyses may yield valuable additional information concerning fibrous cap stress levels which may support current methods of diagnostics.

                   947.       Ultra-Short TE Imaging Protocol for Detection of Aortic Calcification

Daniel A. Herzka1, Reza Nezafat2, Juergen Rahmer3, Warren J. Manning2, Peter Boernert3

1Philips Research North America, Briarcliff Manor, New York, USA; 2Beth Israel Deaconess Harvard Medical School, Boston, Massachusetts, USA; 3Philips Research Europe, Hamburg, Germany

Ultra-short TE sequences are advantageous because they can capture signal from tissues with short T2, while preventing signal loss from sources of artifact such as off-resonance and susceptibility boundaries. We optimized a UTE protocol for visualization of calcified atherosclerotic lesions in vivo in human aortas. The protocol was tested on volunteers and a patient with known atherosclerosis. UTE yielded images with calcium deposits clearly co-localized with atherosclerotic lesions observed with black-blood FSE, and made possible detection of calcification on the luminal side of the aorta. These preliminary results indicate that calcium imaging with MR is feasible and worth further investigation.

                   948.       Signal Features of the Atherosclerotic Plaque at 3.0T Versus 1.5T: Impact on Automatic Classification

William Sean Kerwin1, Fei Liu1, Hunter Underhill1, Vasily Yarnykh1, Chun Yuan1

1University of Washington, Seattle, Washington, USA

We evaluated signal differences between 1.5T and 3T MRI of carotid atherosclerotic plaque using an automatic classifier. Despite being trained on only 1.5T data, subjects scanned at both field strengths yielded highly similar classification results for the presence and average areas of calcification, lipid-rich core, hemorrhage, and fibrous tissue. These results suggest that signal properties are sufficiently similar at 3T relative to 1.5T that classifier performance is not significantly affected.

                  949.       Long Segment Dark Blood Carotid Artery Imaging with Pencil-Beam-Excitation and Diffusion
                                Preparation at 3T

                                 Axel Bornstedt1, Peter Bernhardt1, Vinzenz Hombach1, Markus Kunze1, Jochen Spiess1, Nico Merkle1, Volker Rasche1

                                1
Uniklinik Ulm, Ulm, Germany

Robust long segment (~150 mm) 3D dark blood vessel visualisation of the carotid arteries at 3T is accomplished with pencil beam excitation and diffusion prepared gradient echo imaging.

                   950.       Magnetic Resonance Imaging Parameters of Atherosclerotic Plaque Burden Successfully Predict
                                 Manifested Cardiovascular Disease

Venkatesh Mani1, Hamza El Aidi1, Mark Woodward1, Paul Muntner1, Silvia H. Aguiar1, Karen Beth Weinshelbaum1, Hiroaki Taniguchi1, John E. Postley2, Valentin Fuster1, Zahi A. Fayad1

1Mount Sinai School of Medicine, New York, New York, USA; 2Columbia University, New York, New York, USA

The purpose of this study was to evaluate if MRI plaque burden measures in conjunction with traditional risk factors improve predictive capacity for cardiovascular disease (mCVD) and may therefore be useful in pre identification of patients at risk for cardiovascular disease. MR measures of plaque burden were obtained from 296 patients and ROC curves were used to determine predictive capacity of MR derived parameters for predicting mCVD. Combining MR parameters with traditional risk factors provided highest retrospective predictive capacity for mCVD.

                   951.       Longitudinal Observation of Carotid Artery Intraplaque Hemorrhagic Volume on Magnetic Resonance
                                 Direct Thrombus Imaging

James Qiupeng Zhan1, Alan R. Moody2, General Leung2, Radhakrishnan Ravikumar2, Susan Crisp2

1Sunnybrook Health Sciences Centre, Toronto , Canada; 2Sunnybrook Health Sciences Centre, Toronto, Canada

A study was conducted to measure carotid artery intraplaque haemorrhage (IPH) volume over time using Magnetic Resonance Direct Thrombus Imaging (MRDTI) and correlate it with the occurrence of prior ipsilateral ischemic events.  Patients who received multiple MRDTI scans and were diagnosed with complicated plaque were classified as either symptomatic (having previous events) or asymptomatic. Two trained observers analyzed the MRDTI data and determined IPH volumes. The intra-and inter-reader coefficients of variation were 6.2% and 8.2%, with correlation coefficients of 0.987 and 0.972. Relative mean change in IPH volume was 86.31±266.44% for asymptomatic patients and 10.23±54.87 % for symptomatic patients (P<0.01).

                   952.       Improvements in Spatial Resolution Using a Novel 8-Element Carotid Phased Array Coil at 3T

Niranjan Balu1, Vasily Yarnykh1, Cecil Hayes1, Joshua Scholnick1, Dongxiang Xu1, Baocheng Chu1, Chun Yuan1

1University of Washington, Seattle, USA

Carotid plaque imaging demands high SNR and high resolution. While current four-element phased array (PA) coils provide adequate SNR over a limited FOV, PA coils with additional elements can improve SNR and coverage. Using a  novel eight-element PA (8PA) coil , upto 60% improvement in SNR and CNR were observed with a high-resolution (0.63mm in-plane) protocol.  An ultra-high resolution (0.27mm in-plane) T1w black-blood quadruple inversion recovery sequence was implemented to assess the resolution improvement made possible by the 8PA coil.  The 8PA coil enabled ultra-high resolution imaging with SNR improvements greater than 1.35 times with better vessel wall delineation.

                  953.       Time Dependence of Necrotic Core and Fibrous Cap Quantitative Measurements with Gadobenate
                                 Dimeglumine Enhanced Carotid Plaque MRI at 3T

Kevin DeMarco1, Xiaohai Ma1, John Brooks1, David Zhu1, Vasily Yarnykh2

1Michigan State University, East Lansing, Michigan, USA; 2University of Washington, Seattle, Washington, USA

Contrast-enhanced T1 weighted images (CE T1WI) demonstrate lipid rich necrotic core (LR-NC) with higher contrast-to-noise ratio (CNR) at 1.5T using gadodiamide.  This study extends in vivo carotid plaque imaging to 3T and evaluates the effect of post-injection time on appearance of LR-NC using gadobenate dimeglumine by comparing CNR of LR-NC at 5 and 10 minutes after contrast injection in 43 outpatients with carotid stenosis.  LR-NC CNR was similar at both time points, but with higher signal-to-noise ratio at 10 minutes.  LR-NC volume measurement at both time points employing automated algorithm in MRI-PlaqueView is under investigation as is comparison with histology.

                   954.       Magnetic Resonance Intraplaque Hemorrhage is Associated with Cerebrovascular Outcomes in
                                 Asymptomatic Male Patients with Non-Severe Stenosis

Navneet Singh1, Alan R. Moody1, General Leung1, Ravikumar Radhakrishnan1, James Zhan1, Robert Magissano1

1Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Canada

Intraplaque hemorrhage (IPH) is an emerging marker of plaque instability. We investigated the correlation of MR detected IPH to cerebrovascular outcomes in a group of asymptomatic males with non-severe stenosis. A GE 1.5T MR and an 8 channel neurovascular coil array (USA Instruments, USA) using a 3D T1-weighted, fat-suppressed spoiled gradient echo sequence was used. The group with IPH (n=30) had six events (2 strokes, 1 amF, 3 TIAs) compared to no events in the MR IPH negative group (n=47) (RR = 9.60, 95%CI 1.21 to 75.9, p=0.0320).

                   955.       Fibrous Cap Projection Length: A Better Biomarker of Plaque Vulnerability Than Lipid Core Size

Dongxiang Xu1, Niranjan Balu1, Hunter R. Underhill1, Jianming Cai2, Chun Yuan1

1University of Washington, Seattle, Washington, USA; 2Chinese PLA General Hospital, Beijing, USA

Atherosclerotic disease has become one of the leading causes of death and major disability in the United States. In the past years, with the rapid development of using high resolution magnetic resonance imaging (MRI) technology in assessing atherosclerotic components, more and more evidences have shown that plaque composition is the decisive factor determining plaque vulnerability. Cai et al[1] using gadolinium-based contrast enhanced MRI showed that post contrast T1-weighted images can provide accurate quantitative measurements of the intact fibrous cap (FC) in advanced carotid atherosclerotic plaques in vivo. Based on this observation, an automatic FC detection method was developed and validated in our previous research [2]. In this study, we further explore lesion index Normalized Fibrous cap Projection Length Index (NFPLI). Our preliminary trial result has shown its more predictive power in plaque vulnerability than other plaque measurements.

                   956.       Rapid 3D Vessel Wall Imaging at 3T:  Optimization of Diffusion Preparation and Comparison to Other
                                  Protocols

Mahender K. Makhijani1, Gerald S. Pohost2, Krishna S. Nayak1

1University of Southern California, Los Angeles, California , USA; 2University of Southern California, USA

Multi-contrast high-resolution imaging is used to characterize carotid plaque components. Standard multi-slice methods have long scan times and are not suited for plaque quantitation. Diffusion preparation has been recently proposed as a means for blood suppression in 3D vessel wall imaging. We characterize the tradeoffs of this approach when applied in conjunction with DIR and evaluate its performance at 3T in-vivo for bilateral carotid imaging and compare it with standard protocols and 3D SSFP approach. Cardiac gated 3D carotid vessel-wall datasets with 0.5x0.5x2.5 mm3 resolution over a 16x3.2x5cm3 FOV, and vessel wall CNR > 18, were obtained in 100 seconds

                   957.       Detection of Plaque Vascularity Using Delayed Contrast Enhanced MRI: Correlation with Contrast
                                 Enhanced Ultrasound

Radhakrishnan Ravikumar1, Alan R. Moody1, General Leung1, James Q. Zhang1, Peter N. Burns1, Susan Crisp1, Marilyn Robertson Horton1, Robert Maggisano1

1Sunnybrook Health Sciences Centre, Toronto, Canada

Plaque neovascularity, in addition to nurturing plaque growth can also be a causative factor for intraplaque hemorrhage thus predisposing the patient to increased risk of cerebrovascular events. Contrast enhanced ultrasound has been effectively used in identifying plaque neovascularity. The main purpose of this study was to see whether contrast enhanced MRI can help identify neovessels within the plaque and to compare the MR findings with contrast ultrasound findings. Delayed enhancement uptake patterns visualised on MR correlated well with neovascularity positive areas detected on contrast ultrasound.

                958.       High-Resolution T1- And T2-Weighted Black Blood Inner Volume 3D Fast Spin Echo Imaging for
                             Characterizing Vessel Wall Components in Vivo

Dimitris Mitsouras1, Robert V. Mulkern1, 2, Christopher D. Owens1, Tianxi Cai3, Amanda G. Whitmore1, Hale Ersoy1, Michael S. Conte1, Mark A. Creager1, Frank J. Rybicki1

1Harvard Medical School & Brigham And Women's Hospital, Boston, Massachusetts, USA; 2Children's Hospital, Boston, Massachusetts, USA; 3Harvard School of Public Health, Boston, Massachusetts, USA

Saphenous vein femoral-popliteal bypass graft imaging using a high spatial resolution (0.312mm in-plane) black-blood inner-volume 3DFSE sequence in 14 subjects revealed significantly larger wall area measured from T1W than T2W images (median ratio 1.52, median difference 5.45mm2, P<0.001). This significant difference was due to an increased outer wall boundary. T2 relaxometry of two specimens revealed shorter T2 values in an outer vs. an inner wall layer, accounting for the in vivo finding of differing areas measured from different contrast weightings. Correlative histology attributed the shorter T2 in the outer layer to collagen-rich fibrous tissue vs. myofibroblasts embedded in proteoglycan-rich matrix.

                   959.       Gender Differences in Aortic Wall Thickness Regression by Magnetic Resonance Imaging (MRI) and Its
                                  Association to HDL Profile: The Plaque Follow Up Study by the National Institute of  Aging (NIA)

Gustavo Khattar Godoy1, Veronica R.S Fernandes1, Hossein Bahrami1, Christopher Sibley1, Ilan Gottlieb1, David A. Bluemke1, Joao A.C Lima1

1Johns Hopkins University, Baltimore, USA

The aim of the study was to assess the relationship between changes in aortic wall thickness measured by MRI with lipid profile and gender,of 114 participants of a randomized clinical trial using lipid-lowering drugs for 2 years.Were analized 3 segments of the thoracic aorta (ascending,arch and descending),using a double inversion recovery black blood fast spin-eco sequence with ECG-gating and T1-Weighted post-gadolinium.Were found a significant lower rate reduction of the aortic thickness in men when compared to women.Greater HDL levels were related to a decrease in ascending aortic wall thickness ,after adjustments for variables.

                   960.       Quantitative Comparison of Carotid Plaque Composition Between 1.5 and 3.0T Field-Strengths

Hunter R. Underhill1, Vasily L. Yarnykh1, Thomas S. Hatsukami1, Jinnan Wang1, Niranjan Balu1, Cecil Hayes1, Minako Oikawa1, Wei Yu1, Dongxiang Xu1, Baocheng Chu1, Bradley T. Wyman2, Nayak L. Polissar3, Chun Yuan1

1University of Washington, Seattle, USA; 2Pfizer, Groton, USA; 3The Mountain-Whisper-Light Statistical Consulting, Seattle, USA

We sought to assess the effects of field-strength on the quantification of carotid atherosclerotic disease.  Participants with 16-79% carotid stenosis underwent high-resolution carotid MRI at both 1.5T and 3.0T.  There was strong agreement between field-strengths in quantitative measurements of plaque morphology and detection of plaque components.  However, the increased magnetic susceptibility of calcification and a stronger effect of paramagnetic ferric iron in hemorrhage at 3.0T may introduce a quantitative bias in measurements of these components.  As such, 3.0T imaging may improve the detection of calcification, but more sensitive imaging techniques may need to be used for hemorrhage evaluation at 3.0T.

                   961.       Improved Motion-Sensitized Driven Equilibrium (IMSDE) Blood-Suppression Sequence for
                                 Atherosclerosis  Plaque Imaging at 3T

Jinnan Wang1, 2, Vasily L. Yarnykh1, Baocheng Chu1, Chun Yuan1

1University of Washington, Seattle, Washington, USA

In this study, an improved version of motion sensitization driven equilibrium (iMSDE) sequence was proposed for carotid artery vessel wall imaging. By adding a new refocusing pulse, the iMSDE sequence is less sensitive to the B1 inhomogeneity at high field strength. Both phantom test and in vivo imaging has demonstrated that iMSDE sequence can  dramatically increase signal level, when comparing with traditional MSDE sequence, without losing flow suppression efficiency.

                   962.       High-Resolution Ultra-Short TE Imaging of Ex Vivo Human Carotid Plaques Correlates with CT

Daniel A. Herzka1, Juergen Rahmer2, Reza Nezafat3, Ray Chan1, Wei Liu1, Peter Boernert2

1Philips Research North America, Briarcliff Manor, New York, USA; 2Philips Research Europe, Hamburg, Germany; 3Beth Israel Deaconess Harvard Medical School, Boston, Massachusetts, USA

Ultra-short TE (UTE) sequences have the advantage that they are able to capture signal components with very short T2. We investigate the use of single and multi-echo UTE sequences for the detection of calcium deposits in ex vivo human carotid samples with known atherosclerosis. UTE images correlated significantly with high-resolution CTs but with better soft-tissue contrast. Though low in intensity, the signal from calcifications is detectable with UTE MRI and may be complementary to current multicontrast atherosclerotic tissue characterization approaches. Further work is required to assess the feasibility of these acquisitions in vivo.

                   963.       Passive Targeting of Atherosclerosis with Paramagnetic Lipid Nanoparticles in a Mouse Model of
                                 Vulnerable and Stable Plaques

Glenda Sibylle van Bochove1, Leonie E M Paulis1, Dolf Segers2, Willem J M Mulder3, Rob Krams4, Gustav J. Strijkers1, Klaas Nicolay1

1Eindhoven University of Technology, Eindhoven, Netherlands; 2Erasmus Medical Center, Rotterdam, Netherlands; 3Mount Sinai School of Medicine, New York, New York, USA; 4Imperial College London, London, UK

Recently, a mouse model has become available where both stable and vulnerable atherosclerotic plaque phenotypes are induced by the placement of a tapered cast around the right carotid artery of apoE-/- mice. The aim was to evaluate the contrast generated in these plaques by injection of Gd3+ liposomes and Gd3+-micelles to obtain insight in plaque permeability. Both stable and vulnerable plaques appeared non-permeable for liposomes, while accumulation of micelles was observed in both lesion types. Therefore, liposomes are a good candidate for targeting endothelial markers and micelles may also be suitable for targeting factors inside the atherosclerotic plaque.

                   964.       Molecular Imaging of Atherosclerosis Using PEG-Micelles Targeted by an ApoE Derived Peptide

Eik Leupold1, Esad Vucic2, Willem Mulder2, Margitta Dathe1, Zahi Adel Fayad2

1Leibniz Institute of Molecular Pharmacology (FMP), Berlin, Germany; 2Mount Sinai School of Medicine, New York, USA

We use Gadolinium labeled PEG-micelles as contrast agents for MRI with ApoE knockout mice as atherosclerosis models. Targeting is achieved by an ApoE derived peptide (A2). The PEG-micelles consist of maleimide-PEG-DPPE, Gd-DTPA-BSA and rhodamine-DPPE. The micelles are produced by lipid-film hydration and A2 is coupled via maleimide/sulfhydryle conjugation.The micelles are 18nm in diameter and have a high stability. In vivo application (50mmol Gd/kg) results in a high, long lasting enhancement of atherosclerotic plaque in MRI using a 9.4T system. The maximum enhancement of 129±46% is reached at 24h, compared to 30±15% in mice treated with control PEG-micelles. Confocal microscopy was performed on sections taken from the thoracic aorta. A co-localization of A2 PEG micelles with macrophages in atherosclerotic plaques could be shown.A2 modified PEG-micelles containing Gd are a new contrast agent that is excellently suited for the MRI based diagnosis of atherosclerosis.

                  965.       Comparison of Synthetic HDL Contrast Agents for Atherosclerosis Imaging

David Peter Cormode1, Rohith Chandrasekar2, Karen C. Briley-Saebo1, Alessandra Barazza1, Willem J. Mulder1, Edward A. Fisher3, Zahi Adel Fayad1

1Mount Sinai School of Medicine, New York, USA; 2The Cooper Union for the Advancement in Science and Art, New York, USA; 3New York University, New York, USA

We have previously reported a macrophage specific MRI contrast agent based on HDL. To make this agent more versatile, we have formed Gd-labeled, synthetic HDL using a 37 or 18 amino acid peptide that mimics apoA-I, the main protein constituent of HDL. The effectiveness of these peptide-agents for detecting macrophages in the abdominal aorta of apoE knockout mice is assessed via MRI studies. Targeting to macrophages is confirmed by confocal microscopy. In addition, the biodistribution and pharmacokinetics are reported and the therapeutic properties of these particles in terms of removing cholesterol from macrophages are investigated.

                   966.       Imaging Vasulcar Injury Using a Novel Gadolinium-Based Contrast Agent

Pauliina Lehtolainen1, Manfred Junemann-ramirez, Panagiotis Kyrtatos1, Anthony N. Price1, Kenjiro Ikuta2, Yoshiki Katayama2, John F. Martin, Mark F. Lythgoe

1 Institute of Child Health and Department of Medicine, University College London, London, UK; 2Kyushu University,, Fukuoka, Japan

The vasculature is one of the most promising targets for a site -specific MRI strategy, as the diagnosis of vascular disease in its early stages is essential to a successful treatment intervention. Here we report on an endothelial-lesion specific contrast agent, evans-blue chelated gadolinium (EB-DTPA-Gd) for imaging the vascular damage and regeneration of vascular wall. Vascular injury generated by angioplasty was clearly distinguished by EB-DTPA-Gd accumulation by T1-weighted MR images using 9.4T scanner.

                   967.       Comparison of Gadofluorine M and Gd-DTPA Relaxivities for Quantitation and Characterization of
                                 Atherosclerotic Plaque in Mouse at 11.7T

Haiying Tang1, Richard Kennan1, Ching H. Chang1, Bernd Misselwitz2, Donna Suresch1, Dan Zhou1, Brett Connally1, Michael Klimas1, Donald S. Williams1, Richard Hargreaves1, Haiying Liu1

1Merck Research Laboratories, Rahway, New Jersey, USA; 2Bayer Schering Pharma AG, Berlin, Germany

Recent advances in MRI technology and novel imaging contrast agents have made MRI an important imaging modality for detecting and characterizing atherosclerosis. Gadofluorine M has been reported to target the extracellular matrix of plaque, and is an important marker of plaque staging. Comparisons of relaxivities and dose response in plaque are made between Gd-DTPA and Gadofluorine M at 11.7 Tesla. The results confirm that Gadofluorine M greatly helps in the identification and quantitation of plaque burden in major arteries of mouse model of atherosclerosis with improved sensitivity and efficiency, and may provide better characterization of plaque components at different stages.

                   968.       Imaging of Macrophage Infiltration in an Abdominal Aortic Aneurysm Mouse Model

Gregory Harrison Turner1, Alan R. Olzinski1, Roberta E. Bernard1, Karpagam Aravindhan1, Heather W. Karr1, Robert N. Willette1, Peter J. Gough1, Beat M. Jucker1

1GlaxoSmithKline, King of Prussia, Pennsylvania, USA

Abdominal aortic aneurysms result from a vascular inflammatory process involving macrophage recruitment.  Abdominal aortic aneurysms (AAA) can be consistently produced in hyperlipidimic ApoE-/- mice by continuous infusion of Angiotensin-II (Ang-II).  Administration of USPIO was used as an imaging biomarker for the distribution of macrophage within an aneurysm. These results demonstrate the feasibility of using a USPIO contrast agent as a surrogate for acute inflammatory processes in the aorta of ApoE-/- mice.

                   969.       GdAAZTA-C17 (Q=2) Labeled High Density Lipoproteins (HDL) for the in Vivo Detection of
                                  Atherosclerotic Plaque

Karen Briley-Saebo1, Simonetta Geninatti2, David Cormode1, Alessandra Barazza1, Wei Chen1, Edward Fisher3, Silvio Aime2, Zahi A. Fayad1

1Mount Sinai School of medicine, New York, USA; 2University of Torino, Torino, Italy; 3New York University, New York, USA

To increase CNR and reduce the dose administered, high relaxivity gadolinium chelates with two water exchange sites (q=2) were integrated into high-density lipoproteins (HDL). The q=2 HDL adduct was characterized relative to GdDTPA-DMPE (q=1) HDL, and the MR efficacy evaluated in mouse models of atherosclerosis. The results indicate that the q=2 lipid integrates into the lipid core. The q=1 lipid, however, formed a micelle that interacted with the surface. Similar MR arterial enhancement was observed after administration of 0.048 mmol Gd/Kg q=1 HDL and 0.018 mmol/Kg q=2 HDL. The q=2 HDL adduct may allow for low dose detection of atherosclerosis.

                    970.       Characterization of an in Vivo Model of Atherosclerosis Using Histological and MRI Techniques

Stephanie Elaine GarWai Chiu1, Alan R. Moody1, James Qiupeng Zhan1, Radhakrishnan Ravikumar1, General Leung1

1Sunnybrook Health Sciences Centre, Toronto, Canada

Intraplaque hemorrhage and plaque neovascularization are recognized as contributors to atherosclerotic plaque vulnerability, but current animal models do not consistently or spontaneously produce these types of lesions.  As a first step towards building upon the commonly used hypercholesterolemic rabbit model, a low dose of recombinant human vascular endothelial growth factor (rhVEGF) was administered to a group of rabbits.  These injections have been shown to increase both intramural endothelial cell and macrophage density in hypercholesterolemic rabbits. MRI using both an intravascular and an extravascular contrast agent was performed on the rabbits in an attempt to detect these changes non-invasively.

 

Cardiac T2 & T2*

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                   1008.     Improved Dark Blood Cardiac Morphology Imaging Using a Navigated ECG-Triggered BLADE
                                 Sequence: Scope of Applications

Magalie Viallon1, Jean-Noël Hyacinthe1, Dominique Didier1, Pierre Croisille2

1Hopital Universitaire de Genève, GENEVA, Switzerland; 2Hopital Cardiologique Louis Pradel, LYON, France

T1 or T2 weighted TSE and T1 SE dark blood (DB) MR imaging (eventually combined with fat saturation (FS) or inversion recovery(IR)) are involved to characterize pathologies like DAVD, tumours, sarcoïdosis, myocarditis,  to determine the area-at-risk in acute myocardium infarction (MI) or to detail cardiac morphology in congenital disease. But Dark-blood TSE methods are subject to artifacts (signal loss due to incoherent cardiac motion from RR length changes), resolution is restricted by the breathhold duration and remain low. In free breathing paediatric patients TSE DB techniques is dramatically hindered by the respiratory motion. PROPELLER then BLADE were new encoding strategies implemented to correct for intra and inter scan motion in brain morphological acquisition and offer a solution in uncooperative patients (Parkinson, stroke or Alzheimer diseases). We investigate here the capabilities of BLADE to circumvent motion sensitivity in DB cardiac morphology imaging and improve image quality.

                  1009.     Detecting Right Ventricular Involvement in Reperfused Myocardial Infarction with T2-Weighted
                                Cardiac MR and IR-Prepared SSFP with Delayed Contrast Enhancement

Yuesong Yang1, Ram Vijayaraghavan1, Jay Detsky1, John J. Graham1, Warren Foltz1, Alexander Dick1, Graham A. Wright1

1Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Canada

Right ventricular (RV) myocardial infarction and dysfunction are independent indicators of poor prognosis in patients with acute myocardial infarction (AMI). Conventional DE-MRI has a limited role in the detection of the RV involvement in reperfused MI due to the thinned RV wall and pericardial fat tissue. We hypothesize that a T2-weighted cardiac MR technique with fat saturation is a better method to identify RV involvement in the acute stage of MI, and that the DE-MRI technique based on IR-prepared SSFP is a better technique to demonstrate RV involvement in the chronic stage of MI.

                  1010.     Optimization of T2 and T2* Measurement in Myocardium at 3.0 T

Jared Guthrie Cobb1, 2, Huairen Zeng2, 3, Cynthia Paschal2

1Vanderbilt University , Nashville, Tennessee, USA; 2Vanderbilt University, Nashville, Tennessee, USA; 3Vanderbilt University Medical Center, Nashville, Tennessee, USA

High field clinical scanners are increasingly available to researchers and clinicians and possess a significant SNR advantage over 1.5T scanners.  New accelerated imaging techniques designed to optimize spatial and temporal acquisition may allow researchers to detect subtle changes in myocardial tissue, including changes that may be indicators of differences in oxygen utilization such as variations in T2 and T2*. In pursuit of this goal, we developed optimized breath hold scans to measure T2 and T2* in the myocardial septum at 3.0T.

                  1011.     Single-Shot SSFP for Imaging of Edematous Myocardium in Patients

Jordin D. Green1, 2, James Reavley Clarke2, Matthias G. Friedrich2

1Siemens Medical Solutions, Calgary, Canada; 2University of Calgary, Calgary, Canada

Cardiovascular MR can be used to visualize myocardial edema, a characteristic of patients with acute myocardial infarcts, but can be challenging in difficult patients. SSFP is T2/T1-weighted in the steady state with high imaging efficiency. The purpose of this study was to demonstrate the feasibility of using single-shot SSFP to image myocardial edema. The study was conducted in six patients. Results were compared to a conventional T2-weighted STIR sequence. Of the 32 myocardial segments positive for edema according to the STIR sequence, 24 were positive using SSFP. Of the 52 negative for edema according to STIR, 45 were negative using SSFP.

                  1012.     Enhanced Detection of Myocardial Edema with Spectrally Selective Inversion Recovery-Prepared
                                 T2-Weighted Imaging

Myra Sabene Cocker1, Oliver Strohm1, Jordin Daniel Green, 12, Steven M. Shea3, Hassan Abdel-Aty1, Matthias G. Friedrich1

1Libin Cardiovascular Institute at the University of Calgary, Calgary, Canada; 2Siemens Medical Solutions, Calgary, Canada; 3Siemens Corporate Research Inc., Baltimore, Maryland, USA

AASPIR (Asymmetric Adiabatic Spectral Inversion Recovery) was compared with STIR (Short T1 Inversion Recovery) for T2-weighted cardiovascular magnetic resonance (CMR) imaging of global and regional myocardial edema.  Our findings support the implementation of AASPIR instead of STIR to visualize myocardial edema, as AASPIR allows for increased SNR and improved image quality.

                  1013.     T2* Measurements in Myocardial Iron Overload: Comparison of Error Models on Optimized
                                 Analysis Protocol

Marco Borri1

1University of Turin, Turin, Italy

Iron-induced heart failure is the main cause of death in transfusion-dependent anemia. In the presence of tissue iron, the shortening of the relaxation time constant T2* is used for detection of cardiac iron. It has been shown that patients with short T2* - corresponding with myocardial iron loading - have greater risk of systolic dysfunction. T2* measurements are performed with standardized protocols. An error estimation would help the clinical comparison of T2* measurements, especially in single patient’s follow-up. In this work an optimized analysis protocol is indicated and five different error models are compared.

                  1014.     Comparing Myocardial T2* and T2 Measurements in Thalassemia Patients

Taigang He1, Peter D. Gatehouse1, Gillian C. Smith1, Raad H. Mohiaddin1, Dudley J. Pennell1, David N. Firmin1

1Royal Brompton Hospital and Imperial College London, London, UK

The aim of this study is to compare myocardial T2* and T2 measurements in vivo in order to establish the relationship between them. In total 137 thalassemia patients were scanned on a 1.5T MRI scanner. It indicates that T2* of 20ms is a useful indicator to identify patient with cardiac iron. It also demonstrates that mmyocardial T2* measurement correlated linearly with T2 measurement in TM patients with iron overload. These findings suggests that both T2* and T2 measurements can be used for assessment of iron overload in the heart for transfusion dependent diseases such as thalassemia.

                  1015.     Multi-Spiral MRI for Cardiac T2-Star Determination

Philipp Ehses1, Nicole Seiberlich1, Peter Nordbeck1, Florian Fidler2, Peter Michael Jakob1, 2, Wolfgang Rudolf Bauer1

1University of Würzburg, Würzburg, Germany; 2Research Center Magnetic-Resonance-Bavaria, Würzburg, Germany

Cardiovascular T2* magnetic resonance imaging is a valuable tool in the diagnosis of heart disease. In this work, a multi-spiral method for cardiac T2* determination is presented. A multi-spiral sequence is one that acquires each spiral arm multiple times after an excitation in order to generate multiple T2* contrasts. The spiral trajectory was chosen because it inherently refocuses motion- and flow-induced phase errors, which can be beneficial for cardiac applications.

                  1016.     Postmortem Insitu MRI as an Adjunct to Autopsy for the Diagnosis of Myocardial Infarction

Christian Jackowski1, 2, Marcel Warntjes1, 3, Anders Persson1, Michael Thali2, Johan Berge4

1University of Linköping, Linköping, Sweden; 2University of Bern, Bern, Switzerland; 3Division of Clinical Physiology, University of Linköping, Linköping, Sweden; 4Department of Forensic Medicine, Linköping, Sweden

Autopsy diagnosis of myocardial infarction (MI) is still challenging because many lethal ischemic events do not lead to visible myocardial alterations. In these cases the lack of survival time prohibits myocardial reactions after ischemia, such as edema and inflammatory responses. Postmortem non-contrast enhanced insitu MRI (pm-MRI) may support the diagnosis of peracute MI. Being extremely sensitive to water distribution alterations within the myocardial tissue pm-MRI can accurately visualize areas of decreased micro-circulation. The extent of the ischemia is shown by a lowered signal in T2-weighted and proton density weighted images that have been optimized for the post-mortem conditions. As pm-MRI also reliably demonstrates acute, subacute and chronic infarction it might even serve as an alternative in cases in which traditional autopsy is refused for different reasons.

                  1017.     Diffusion-Weighted Imaging Improves the Quantification of Myocardial Oxygenation When
                                 Arrhythmias Are Present

Kyle Stephan McCommis1, Ioannis Koktzoglou2, Haosen Zhang1, Debiao Li2, Robert J. Gropler1, Jie Zheng1

1Washington University School of Medicine, St. Louis, Missouri, USA; 2Northwestern University, Chicago, Illinois, USA

Double-inversion-recovery (DIR) and diffusion-weighted (DW) prepared T2 images were obtained to determine the myocardial oxygen extraction fraction (OEF) in stenotic canines. These T2 and hyperemic OEF values were determined in the left-anterior descending (LAD) stenosis-subtended region and the remote normal left-circumflex (LCX) region. No significant T2 or OEF differences were found between the two methods. However, the DW technique shows better image quality and OEF accuracy when irregular EKG-triggering or arrhythmias occurs.

                  1018.     Myocardial Iron Distribution in Thalassemia: An in Vivo Study with Black Blood T2* Imaging

Taigang He1, Peter D. Gatehouse1, Dudley J. Pennell1, David N. Firmin1

1Royal Brompton Hospital and Imperial College London, London, UK

A black blood T2* technique was employed to investigate myocardial iron distribution in 55 thalassemia patients. The study was conducted on a 1.5T MRI scanner. Images were obtained in the mid-ventricular with 8 echo times and compared for each patient. This is the first in vivo study to demonstrate that myocardial iron deposition is uneven and dominantly in the epimyocardial region in iron overloaded thalassemia patients. This finding agrees well with previously published autopsy reports. These data suggest that T2* measurements in-vivo should use large transmural regions of interest.

                  1019.     Longitudinal Analysis of Heart and Liver Iron in Thalassemia Major

Leila Noetzli1, Nilesh Ghugre1, Thomas Coates1, John Wood1

1Childrens Hospital Los Angeles, Los Angeles, California , USA

The relationship between heart and liver iron in patients with thalassemia major has been complex and ambiguous.  There has been evidence of high liver iron being associated with high heart iron, but there seems to be no correlation between the two at any given time.  To address this issue, we retrospectively analyzed patients who had three or more MRIs to estimate their liver and heart iron.  Through this longitudinal analysis, we found that the majority of patient’s hepatic iron concentration (HIC) versus cardiac R2* trajectories follow a counterclockwise hysteresis loop.  In particular, heart iron lags with respect to liver iron.  This finding is helpful to understand the complex relationship between heart and liver iron movement.

 

MR Safety:  Fields

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                   1045.     SAR and Temperature Compared to Limits in Simulations of a Dedicated Extremity Coil

Zhangwei Wang1, Timothy J. Mosher1, Christopher M. Collins1

1Penn State University, Hershey, Pennsylvania, USA

Little information has been published regarding the SAR distributions in extremities using dedicated extremity coils. This has led to gross extrapolations from data calculated for other parts of the body, such as the head, to determine operating limits in extremity imaging. Here we evaluate what RF power levels can be used in imaging of the human knee with a dedicated extremity coil without exceeding IEC or FDA limits on SAR or temperature.

                  1046.     SAR Evaluation of 7.0 Tesla Perfusion Imaging with Arterial Spin Labeling Coil

Shumin Wang1, Hellmut Merkle1, Lalith Talagala1

1LFMI/NINDS/NIH, Bethesda, Maryland, USA

We examined the safety of neck labeling coils at 7.0 Tesla by using both numerical simulations and experimental data. This study combines the SAR contribution of a CASL neck labeling coil during RF labeling and that of a volume transmit coil during image acquisition. Results indicate that CASL perfusion with a neck labeling coil will be possible at even higher fields without exceeding the SAR guidelines.

                  1047.     9.4 T RF Heating: In Vivo Thermoregulatory Temperature Response in Porcine Models

Devashish Shrivastava1, Robert Schlentz1, Jeramy Kulesa1, Lance DelaBarre1, Carl Snyder1, Timothy Hanson1, J. Thomas Vaughan1

1University of Minnesota, Minnesota, USA

In vivo thermoregulatory response to RF heating at 9.4 T was studied by measuring temperatures in the heads of eight human-sized porcine models. Temperatures were measured in the scalp and brain by fluoroptic thermometry. Continuous wave RF power was delivered for 2.5-3.4 hours to four anesthetized animals. A four loop head coil was used, which was tuned to 400 MHz. The SAR was maintained close to 3 W/kg. Sham RF was delivered to the other four anesthetized animals to understand the effect of anesthesia on temperatures. Run-away heating response was seen in three out of four RF heated animals.

                  1048.     Proton Resonance Frequency Shift Based NMR Thermometry for Ultra-High Field RF Safety Appl

Devashish Shrivastava1, Lance DelaBarre1, Shalom Michaeli1, Carl Snyder1, Timothy Hanson1, J. Thomas Vaughan1

1University of Minnesota, Minnesota, USA

The relative variation in the slopes of proton resonance frequency shift related phase changes was studied over 34.6 and 40.6  C in a non-perfused porcine brain at 7 T. This was done to develop an MR thermometry technique with sub-degree celsius accuracy to measure RF heating in porcine models at ultra-high fields. The phase-change slope varied between (-0.01 ppm/ C) and (-0.015 ppm/ C) in the porcine brain.

                  1049.     Subjective Acceptance of 7T: Initial Experience in the First 210 Subjects

Jens Matthias Theysohn1, 2, Stefan Maderwald1, 2, Oliver Kraff1, 2, Christoph Moenninghoff1, 2, Wolfgang P. Becker1, 2, Patrick Kokulinsky1, 2, Michael Forsting1, 2, Mark E. Ladd1, 2, Susanne C. Ladd1, 2

1University Duisburg-Essen, Essen, Germany; 2University Hospital Essen, Essen, Germany

The introduction of ultra high field MRI systems for clinical human imaging leads to a raised consciousness regarding subjective patient acceptance and appearance of side-effects. We present our data collected from the first 210 human subjects undergoing a 7T MRI examination. Following the examination, potential sources of discomfort and side effects were rated on a 10-point scale and documented. General acceptance was high and side-effects tolerable. We believe that the willingness to undergo such an examination will be even higher if medical benefit for the individual is expected. No critical situation occurred.

                  1050.     Lowering the Imager Significantly Reduces the Field Exposure of MRI Occupational Workers

Adnan Trakic1, Hua Wang1, Feng Liu1, Hector Sanchez Lopez1, Ewald Weber1, Stuart Crozier1

1The University of Queensland, Brisbane, Australia

In MRI, healthcare workers can be exposed to strong static and time-varying magnetic fields outside the imager, which can lead to the stimulation of electric fields in the body. Tissue of the central and peripheral nervous system (CPNS) in the head and torso is particularly susceptible. Reported is a simple solution that can notably reduce the head/trunk exposure of MRI operators to both static and low-frequency magnetic fields. The numerical results indicate that the upper body CPNS exposure can be reduced by factors of up to 50 or more, when the scanner is lowered by 1 m in height relative to the normal operator position.

                  1051.     Simple Analytical Equation of the Induced E-Field

Esra Abaci1, Emre Kopanoglu1, Vakur Behcet Erturk1, Ergin Atalar1

1Bilkent University, Ankara, Turkey

During MRI, due to the time varying magnetic field, electric field is induced. To derive simplified expression of induced E-field in a cylindrical homogenous volume with radius  ρ 0 and conductivity s the gradient fields are assumed to be uniform. The analytical E-field expression is simplified using low frequency based assumptions. The result satisfies the expected conditions, e.g. the divergence of E-field is zero and also it is in line with our intuitive understanding on what E field should be. With this simplified expression, electric field behavior inside the body can easily be defined without an additional computational work.

                  1052.     Induced Magnetic Forces in the Human Head During MRI Procedures: A Group Analysis

Ruiliang Wang1, Dardo Tomasi1, Gene-Jack Wang1, Elisabeth C. Caparelli1, Rita Z. Goldstein1, Nora D. Volkow2, Joanna S. Fowler1

1Brookhaven National Laboratory, Upton, USA; 2National Institutes of Health, Bethesda, USA

Understanding the complex distribution of magnetic field gradients and the induced magnetic forces in human head during magnetic resonance imaging is an important safety issue, particularly for high filed MRI. The magnetic force acting on biological tissues that are exposed to an external magnetic field is proportional to tissue susceptibility and the spatial distribution of the static magnetic field. The aim of this work was to map the magnetic force acting on biological tissues of the human head when the subject’s heads are placed in the homogeneous magnetic field of an MRI scanner for a group of healthy subjects

                  1053.     Tailoring of Gradient Coils for Numerical Exposure Evaluations Based on Experimentally Measured B-Field

Feng Liu1, Adnan Trakic1, Hector Sanchez Lopez1, Ewald Weber1, Stuart Crozier1

1The University of Queensland, Brisbane, Australia

Assessment of MRI worker exposures to pulsed magnetic fields produced by gradient coils has recently attracted a lot of awareness in the field of occupational health and safety. To accurately model the exposures, a full three-dimensional distribution of the magnetic field in the vicinity of the magnet end is required. Unfortunately, for many MRI installations, the coil pattern that generates this magnetic field is often not provided by the manufacturer. A method is presented in which the prediction of a current distribution that generates a nearly identical magnetic field pattern is constrained by a number of experimentally measured magnetic field sample points outside the gradient set of interest. The method takes into consideration other important descriptors such as field uniformity in the working volume, gradient coil geometry, driving current, gradient strength, active shielding etc. To demonstrate the application of the method, current density and matching magnetic field distributions of x- and z-axis gradient coils are derived. This enables robust, accurate evaluations of exposures of tissue-equivalent numerical worker models without pre-knowledge of gradient coil patterns.

                  1054.     Tissue-Mimicking Phantoms for a Combined Magnetic Resonance (MR)/ultra-Wideband (UWB)
                                 Radar Technique
 [Not Available]

Florian Thiel1, Florian Schubert1, Werner Hoffmann1, Frank Seifert1

1Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany

Our research is aimed towards the synergetic technological development of ultra-broadband (UWB) sounding combined with magnetic-resonance imaging (MRI), to access innovative fields of application such as the imaging of cardiac blood vessels and heart beat monitoring, accurate modelling of electromagnetic wave propagation through heterogeneous, malignant and benign, biological tissue for high-field MRI, and fast and precise identification and localisation of breast cancer. As our first step towards this ambitious aim we report on moveable multilayer tissue-like phantoms specifically designed for testing and development of a UWB-MRI combination setup.

                  1055.     MRI Safety: Quantitative Comparison of RF-Heating on Different MR Scanners Based on the
                                 High Frequency B1-Field

Florian Fidler1, Toni Hippmann2, Marcus Warmuth3, Philipp Ehses4, Peter Nordbeck3, Michael T. Friedrich5, Wolfgang Geistert5, Walter Kullmann2, Peter Michael Jakob, 14, Wolgang Rudolf Bauer3

1Research Center Magnetic-Resonance-Bavaria, Würzburg, Germany; 2Fachhochschule Würzburg-Schweinfurt, Schweinfurt, Germany; 3University Hospital Würzburg, Würzburg, Germany; 4University of Würzburg, Würzburg, Germany; 5Biotronik GmbH & Co. KG, Berlin, Germany

The understanding of heating effects in MRI, especially in patients with medical implants, is one of the most important issues in MRI safety. Local electric fields are known as the cause of implant heating, but these are in general not accessible. The vast majority of the electric field is induced from eddy currents generated by the high frequency magnetic B1-field. The purpose of this work was to give a quantitative comparison of SAR maps and therefore heating results on different MRI systems and a simulation based on the knowledge of the B1-field.

 

RF Transmit Array Hardware

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  1089.     Suppressing Transmit Coil Load Change Effects with Ultra-Low Output Impedance RF Power Amplifier

Xu Chu1, Juan Sabate2, Yudong Zhu2

1GE Global Research Center, Shanghai, People's Republic of China; 2GE Global Research Center, Niskayuna, New York, USA

Current variation in a transmit coil due to load change can be substantial in a setup using a conventional RF power amplifier. The capability of a newly developed ultra-low output impedance RF power amplifier in suppressing such current variation is explored. The new amplifier, when connected to drive a transmit coil with L-type input-matching network, acts approximately as a current source, suppressing current variation due to load change and/or EM coupling. Meanwhile, the output-matching network of the MOSFET transforms the input impedance of the coil into the optimum load of the MOSFET, hence maximizing the available output power.

                  1090.     An Integrated Multi-Channel RF Transmitter for Continuous Arterial Spin Labeling with Multiple Label Coils

Adam Martin Winchell1, 2, Ralf Berthold Loeffler1, Yong Zhang1, Ruitian Song1, Kathleen J. Helton1, Lawrence L. Wald3, Claudia Maria Hillenbrand1

1St. Jude Children's Research Hospital, Memphis, Tennessee, USA; 2University of Memphis and UTHSC Joint Biomedical Engineering Program, Memphis, Tennessee, USA; 3Massachusetts General Hospital, Charlestown, Massachusetts, USA

A complete territorial brain perfusion system was developed using three independent surface-coils for the left, right carotid and vertebral arteries.  Three independent trigger signals controlled by the sequence program gated a single external RF pulse to apply flow-driven adiabatic spin inversion for imaging.  This low cost approach was demonstrated in both phantom and volunteer measurements.  The volunteer measurements produced well-defined and localized territorial perfusion images which correspond with expected normal physiological conditions.

                  1091.     RF Current Source Development for Parallel Transmit Arrays Using a High Power MOSFET

WonJe Lee1, Eddy B. Boskamp, Thomas M. Grist, Krishna N. Kurpad

1Uinversity of Wisconsin-Madison, Madison, USA

RF current source technology is gaining ground in parallel transmit arrays in order for B1 field pattern and local SAR control in high fields. In this work we present a RF current source development using a high power MOSFET by means of driven current amplitude and suppression of current induced by a neighboring element. Experimental results demonstrate improved craven current efficiency and reliability against load impedance changes. Simultaneously, current induced by a neighboring element is suppressed by a factor of 17 dB at the closest loop to loop distance by shunting the output capacitance of the chosen MOSFET.

                  1092.     Design of a Strip Transmit Coil/Array for Low Field Open MR

Bing Wu1, 2, Jun Gao1, Jiabin Yao1, Cunli Zhang1, Xiaoliang Zhang2, 3

1GE Healthcare, Beijing, People's Republic of China; 2UCSF, San Francisco, California , USA; 3UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco & Berkeley, California , USA

RF coils with microstrip transmission line structure have shown the advantages for high and ultrahigh field MRI due to the excellent high frequency performance. In this work, we explore the feasibility of transmit body coil or coil array design using microstrip design technique for low-field open MR applications. Result shows that the proposed microstrip transmit (Tx) coil or parallel transmit array appears to be more compact and efficient than the conventional saddle-type transmit coils.

                  1093.     An 8 Channel TX-RX Head Array for Improved SNR at 3T

Frank Resmer1, Markus Klarhöfer2, Titus Lanz1

1Rapid Biomedical GmbH, Rimpar, Germany; 2University of Basel, Basel, Switzerland

The design of an 8 channel TX-RX Array for 3T is described. It provides an SNR comparable to a volume coil of similar dimensions. Sufficient decoupling between elements is vital with TX-RX arrays. So far TX-RX arrays have been built with strip lines or gap designs to decouple individual elements. These approaches provide good intrinsic decoupling but also reduce the coil sensitivity. The coil presented here uses a conventional design with a capacitive decoupling network and so combines a high SNR with good element decoupling.

                  1094.     Efficiency of a 3T Whole Body 16 Channel TEM Transmit Array

Ed Boskamp1, Scott Lindsay1, Patrick Gross2, Hans-Peter Fautz2, Mika Vogel2, John Lorbiecki1, Yudong Zhu3

1GE Healthcare, Waukesha, Wisconsin, USA; 2GE Research, Munich, Germany; 3GE Research, Niskayuna, New York, USA

A 3T whole body 16 channel TEM style transmit array was built and compared to an 8 loop whole body transmit array. The new 16 channel version has an efficiency of 0.231 uT /ãW  of B+1 in the center of the coil when driven in an emulated homogeneous birdcage mode. The new array displays lower temperature than the 8 loop design. This array is connected to an 8 channel transmit chain. Each channel is sending power via splitter to 2 rungs, which can be opposite (180 degree phase difference) or neighboring (22.5 degree phase difference)

                  1095.     7 Tesla Localized RF Excitation/Reception Using a Highly Coupled Coil and Without B1 Measurements

Tamer S. Ibrahim1, YiK-Kiong Hue1, Lin Tang2

1University of Pittsburgh, Pittsburgh, Pennsylvania, USA; 2University of Oklahoma, Norman, Oklahoma, USA

The presented results demonstrate that by properly modeling the load, transmit/receive array, and the excitation/reception scheme, an RF power-controlled B1 shimming can be 1) guided with simulations that require a minimum of computational time required (seconds) and 2) efficiently implemented without any B1 measurements.  Localized excitation/reception is demonstrated using a 7T system.

Text Box:  
                 1096.     Evaluation of a Phase Shifting Matrix for Body Coil B1+ Shimming in a Dielectric Phantom

Elisabeth Beermann1, Patrick Gross2

1GE Healthcare, Solingen, Germany; 2GE Global Research, Munich, Germany

One challenges in high field MRI is the B1-field inhomogeneity due to particular patient RF permittivity. This results in artifacts in the MR images and thus can compromise their diagnostic value. RF shimming and parallel transmit offer a potential solution to this challenge.  In order to interface an 8-channel system with a 16-channel transverse-electromagnetic (TEM) body-array, the use of a phase shifting or Butler matrix was investigated and B1 shimming in a dielectric phantom was performed. The results for a dielectric phantom thus indicate that the advantages of using a phase shifting matrix are similar to those in a non-dielectric phantom previously published. 

                  1097.     Preamp-Like Decoupling and Amplitude Modulation in CMCD Amplifiers for Transmit Arrays

Jeremiah Aaron Heilman1, Natalia Gudino, Matthew J. Riffe, Markus Vester2, Mark A. Griswold

1Case Western Reserve University, Cleveland, Ohio, USA; 2Siemens Medical Solutions, Erlangen, Germany

Development of current-mode class-D amplifier, including improvements for amplitude modulation, greater efficiency, and decoupling.

 

Transceiver & Control Systems

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  1130.     A Simple Vector Modulator Approach to Phase and Amplitude Control for B1 Shimming

Ke Feng1, Xiaojun Chen1, William A. Grissom2, Douglas C. Noll2, Mary Preston McDougall1, Steven M. Wright1

1Texas A&M University, College Station, Texas, USA; 2University of Michigan, Ann Arbor, Michigan, USA

B1 shimming is an alternative approach to Transmit SENSE as a method of compensating for full-wave effects at high fields. In order to perform B1 shimming, independent amplitude and phase control of the overall RF pulse is required for each element or input port of a multi-port coil. Digital attenuators and phase shifters with sufficient resolution are quite expensive. This paper presents an inexpensive alternative which combines a vector modulator with digital potentiometers to realize a simple and scalable system to control an array for B1 shimming. In addition, by replacing the digital potentiometers with more expensive fast digital-to-analog boards, the system is capable of full modulation for transmit SENSE. 

                  1131.     RF Switching Matrix Enables 128 Channel Architecture and Dynamic Element-To-Receiver Routing

Yuan Ma1, Jennifer A. Black1, Vanish K. Dabra1, William Peterson1

1GE Healthcare, Waukesha, Wisconsin, USA

A high linearity, low-noise radio frequency switching matrix has been created to enable 128-channel architecture and dynamic element-to-receiver routing. This was accomplished using RF simulation tools, careful component selection, and programmable intelligence control.

                  1132.     A Wire-Free, Radio-Frequency, Shielded Projection Window for MRI Suites

David Ian Hoult1, Patricia Gervai1, Uta Sboto-Frankenstein1

1National Research Council Institute for Biodiagnostics, Winnipeg, Canada

The investigation by fMRI of neural mechanisms associated with visual stimuli is now relatively common. However, the absence of high-quality, wire-free projection windows in MRI suites, particularly at the back of the magnet, often forces investigators to place video projectors inside the shielded room. This poses potential hazards including the risk of projector malfunction and over-heating. Thus a salt-solution window with good optical properties is proposed as a solution to this problem.

                  1133.     Reconfiguration of a “standard” Biospec Spectrometer for Simultaneous 2-Channel Acquisitions:
                                Application for Mouse Brain MRI and MRS

Adrian Rengle1, Hélène Ratiney1, Adriana Bucur1, Sophie Cavassila1, Olivier Beuf1

1INSA-Lyon, Université Lyon 1, Villeurbanne, France

In the field of small animal imaging, the interest for phased-array coil imaging is growing but high field MR experimental systems with multiple receiver channels are still rare and the upgrade of existing systems is relatively expensive. In this work, a standard 4.7T Bruker Biospec Avance II spectrometer was modified to allow simultaneous two-channel acquisitions. Modifications were validated on imaging and spectroscopy on metabolite solution phantom as well as on mice brain using a home-made two-channel array coil. Compared to a single-channel surface coil, the mean SNR was improved by about 20%. Modifications realized for proton multiple-channel acquisitions could also be applied for any X-nucleus. Compared to quadrature detection coils, two-channel coils offer the ability to use parallel acquisitions techniques.

                  1134.     Dynamic Downconversion Module for MR Applications

Jennifer A. Black1, Yuan Ma1, Vanish K. Dabra1

1GE Healthcare, Waukesha, Wisconsin, USA

A small down-conversion module was developed for 1.5T and 3T MR imaging subsystems to allow for dynamic amplification and increased system modularity. This module places the frequency of the MR signal within the frequency range of an analog-to-digital receiver board. Noise figure, linearity, and amplification re optimized in this 1-inch by 2.5-inch module, which can be used for “mix-on-coil” surface coil development or within large switching matrices.

                  1135.     Efficient Tune and Match with Multiple Transmit Coils

John P. Strupp1, Edward J. Auerbach1, Ark Gozubuyuk1, Gregor Adriany1, Kamil Ugurbil1, Pierre Francois Van de Moortele1

1University of Minnesota, Minneapolis, Minnesota, USA

An RF switch box with a multi-channel cable assembly was engineered to facilitate the efficient tune and matching of multi-channel transmit coils as used in ultra high field applications.  A particular challenge was finding components that were either made of non-magnetic materials or that could be easily modified to be so.  Typically the system can decreases coil setup time from tens of minutes to just minutes when compared to the traditional method using just an RF sweeper probe tuner and a handful of 50 ohm terminators.

                  1136.     Direct MRI Detection at 3T and 9.4 T Using 16-Bit High-Speed Digital Receiver

Andrzej Jesmanowicz1, James S. Hyde1

1Medical College of Wisconsin, Milwaukee, Wisconsin, USA

A new 16-bit digital receiver with three LTC2208 A/D converters sampling at 100 MHz at 3T and 120 MHz at 9.4T was evaluated for off-line real-time image acquisition.  Tested were: the dynamic range improvement, the maximum usable MRI frequency range and the ability to abandon a reference frequency shift between slice selection pulse and readout time.  At 35T (1500 MHz) the dynamic range increase together with drop of sensitivity makes the dynamic range of this converter equal to the old, 2 MSPS 16-bit A/D converters used in commercial scanners.

                  1137.     Influence of RF Synthesizer Phase Noise on MR Imaging Stability

Martin Nisznansky1, Joerg Stapf1, Markus Vester1, Philipp Hoecht1, Jan Bollenbeck1, Wilfried Schnell1

1Siemens AG Medical Solutions, Erlangen, Germany

phase noise, RF synthesizer, EPI, fMRI, image-to-image stability, SNR

                  1138.     Ultra Low Noise Preamplifier for Transmit/receive Coils: Upgrading MR Systems Without Further
                                Modifications of the Hardware

Johannes Sell1, Florian Fidler2, Toni Hippmann3, Michael Ledwig2, Peter Michael Jakob1, 2

1University of Wuerzburg, Wuerzburg, Germany; 2Research Center Magnetic-Resonance-Bavaria, Wuerzburg, Germany; 3FH Wuerzburg-Schweinfurt, Germany

A concept for a noise matched low noise preamplifier with integrated transmit bypass is proposed. It has a single wire connection and can be integrated into many existing MR systems without the need of additional wiring. Successful tuning/matching of transmit/receive coils has been demonstrated. The design is adjustable for a wide frequency range with minor changes.

                  1139.     A 500 W, Broadband, Non-Magnetic RF MOSFET Amplifier for MRI Use

David Ian Hoult1, Glen Kolansky1

1National Research Council Institute for Biodiagnostics, Winnipeg, Canada

Initial experiences in building a push-pull, 500W, broadband, non-magnetic MOSFET amplifier are described. For use with Cartesian feedback, the amplifier can be placed at the magnet bore entrance. Strategies for dissipating 1 kW of heat are described and cold-plate liquid cooling is advocated. Direct Q-factor measurements confirm that the MOSFET dynamic output resistance alone (without feedback) is not high enough to provide good current blocking in coupled phased-array coils. A 4:1 Guanella toroidal transformer and a pancake autotransformer are advocated to provide broadband power performance while coping with the MOSFETs’ large drain-source capacitance.

                  1140.     Scalable Low-Profile Linear Amplifier Module for Parallel Transmission in MRI

Xiaojun Chen1, Ke Feng1, Mary Preston McDougall1, Steven M. Wright1

1Texas A&M University, College Station, Texas, USA

Parallel transmission has been suggested as a method to improve RF excitation, in paticular, multi-dimensional and spatially selective excitation at high fields. Both B1 shimming and Transmit SENSE require multiple channels of RF amplifiers, though at lower power levels than may be required with single channels. Particularly as the number of channels increases, the power level requirement per channel drops to values that lend themselves to modular compact construction. This abstract reports our progress in developing a low-profile, linear, high-gain amplifier with a high degree of noise blanking. The module reported here generates 45 watts per channel and offers high efficiency, high linearity, low cost and plug-in modality which make it attractive for scalable parallel transmission systems. It could also serve as a driver stage for whole body Transmit SENSE. This work is designated to be used with a vector modulator designed in-house.

                  1141.     On the Operation of Bluetooth Devices Inside the MR Faraday Cage

General Leung1, Garry Liu1, Kevan J T Anderson1

1Sunnybrook Health Sciences Centre, Toronto, Canada

Bluetooth technology provides an attractive means of communicating with devices confined within the Faraday cage of the MR magnet. Unfortunately, the Faraday cage significantly attenuates a Bluetooth signal such that communication becomes unreliable. To circumvent this, a USB Bluetooth transceiver can be placed within the waveguide enabling broadcasting of the Bluetooth signal inside the Faraday shield. The purpose of this study was to quantify the communication reliability of Bluetooth devices compared with image noise contamination by compromising the waveguide.

                  1142.     A Versatile USB-Based Control System for Instrumentation in a Magnetic Field

Derek Foreman1, Glen Kolansky1, David Ian Hoult1

1National Research Council Institute for Biodiagnostics, Winnipeg, Canada

Massively-parallel digital control, from outside the MR suite, of instrumentation (e.g. multiple Cartesian feedback transceivers) in a strong magnetic field close to an MR magnet creates problems of complexity, cross-talk, interference and speed reduction. To solve these problems, a  low-cost, 40 MByte per second USB-based, bi-directional, non-magnetic serial link requiring only 2 coaxial or fibre-optic cables has been implemented, together with a custom programming language that describes the computer-instrument interface hardware.

                  1143.     Quantitative Mechanical Stimulator for FMRI and MicroPET Studies

Wei-Chieh Wong1, Yen-Yu Shih1, 2, Yun-Chen Chiang1, 2, Chien-Hsiang Huang1, 2, Chen Chang2, Fu-Shan Jaw1

1Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan; 2Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan

The present study developed a fully MR-compatible, computer-controlled, pneumatic stimulator to deliver quantitative tactile stimulation. Mechanical stimulation of the hindpaw of rat significantly increased BOLD signal intensity in the primary somatosensory cortex of the hindlimb region (S1HL). The results validated the feasibility of this stimulator and were coincident with the microPET experiment.

                  1144.     A Simple, Robust, Low-Cost Respiratory Trigger Unit for Imaging Rodents in  Whole Body
                                 Clinical Scanners

Karl-Heinz Herrmann1, Enrico Wagner1, Andreas Deistung1, Ines Krumbein1, Jürgen R. Reichenbach1

1Friedrich-Schiller-University, Jena, Germany

Animal experiments are increasingly conducted on clinical MR systems. For rodents, however, the default trigger systems of whole-body scanners are usually not sensitive enough to detect the tiny motions. Therefore, an MRI-compatible low-cost solution for triggering the respiratory motion of small rodents was constructed.  An optical motion detector was used in conjunction with a robust analog electronic circuit, which converts the original optical into an electrical signal, compensates slow drifts and offsets and finally converts the motion signal into a TTL trigger for the clinical whole body MRI scanner.  The trigger was successfully applied in mouse experiments.

                  1145.     An Ultra-Low Field Imaging Instrument and Analysis of Its SNR and Scaling Properties

Byeong-Ho Eom1, Mark Steven Cohen2, Inseob Hahn1, Konstantin I. Penanen1

1California Institute of Technology, Pasadena, California , USA; 2University of California, Los Angeles, Los Angeles, California , USA

We present here a description of a novel approach to MRI operating at less than the earth's field and show that the SNR potential is comparable to that of traditional high field instruments.

                  1146.     Development of a Local RF Shielding Method for Whole Hand Imaging

Shinya Handa1, Kazuya Taniguchi1, Katsumi Kose1, Tomoyuki Haishi2

1University of Tsukuba, Tsukuba, Japan; 2MRTechonology Inc., Tsukuba, Japan

A local RF shielding method has been developed using a conducting plate and a LC balun circuit for a whole hand MRI system. Using an artificial external noise, the RF shielding performance was quantitatively evaluated. The result demonstrated that the whole hand imaging could be performed without a shielded room.

                  1147.     Intuitive Interface for MR Scan Plane Prescription

Rahul Sarkar1, 2, Chrishnika de Almeida1, Noureen Syed1, Sheliza Jamal1, Jeff Orchard1

1University of Waterloo, Waterloo, Canada; 2Sunnybrook Research Institute, Toronto, Canada

We present a novel 3D user interface model for scan plane prescription in MRI.  The interface consists of a hand-held panel that is manipulated by the user in free space, resulting in analogous real-time prescription of the scan plane in the reference volume.  By providing 3D input directly, the interface aims to reduce the cognitive effort associated with conventional interfaces that use the mouse for scan plane prescription.  We describe a basic implementation of this model and the results of a user study that compared the effectiveness of the panel interface with a traditional mouse-based interface.

 

Thermal Therapy & HIFU

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  1218.     Temperature Mapping Close to the Surface of Ultrasound Transducers Using Susceptibility-
                                 Compensated MRI

Andrew Webb1, Eun-Joo Park, Thomas Neuberger, Nadine Smith

1Penn State University, University Park, Pennsylvania, USA

An MRI technique for non-invasively mapping temperature increases close to the surface of an ultrasound transducer is presented. Using conventional sequences, image artifacts caused by the magnetic susceptibility of the ultrasound transducer preclude this type of measurement. Using susceptibility-compensating sequences, temperature measurements can be obtained ~1 mm from the transducer surface. Applications to phased array cymbal tranducers used for non-invasive insulin delivery are shown.

                  1219.     MR-Temperature Maps of a HIFU CMUT

Serena H. Wong1, Ronald D. Watkins1, Mario Kupnik1, Kim Butts-Pauly1, Butrus T. Khuri-Yakub1

1Stanford University, Stanford, California , USA

Noninvasive surgeries with high intensity focused ultrasound (HIFU) under MR guidance are becoming more popular.  Though piezoelectric transducers have been used traditionally for these applications, capacitive micromachined ultrasonics transducer(CMUT) have shown advantages in ease of fabrication, efficient performance, and minimal self-heating. We demonstrate heating of a gel phantom using HIFU from an unfocused CMUT and also monitoring of this heating using MR-temperature maps in a 3.0 T scanner.

                  1220.     3T MR Phased Array as a Hyperthermia Applicator

Selaka B. Bulumulla1, Arjun Arunachalam1, Keith J. Park1, Thomas K. Foo1, Yudong Zhu1

1GE Global Research Center, Niskayuna, USA

Overlapping coil arrays have been used as phased array receivers in parallel receive schemes as well as transmit elements in parallel transmit schemes. In this work, we consider surface coil arrays excited by continuous wave RF sources as RF hyperthermia applicators for oncology. Using numerical analysis and experimental work, we study the heating patterns from loop elements and demonstrate the feasibility of selective heating from surface coils. The resulting array has the potential to function as parallel transmitters and phased array receivers for diagnostic imaging as well as an applicator for hyperthermia oncology therapy.

                  1221.     Evaluation of Nanoshell Mediated Tumor Ablation with Real Time Multiplanar MR Temperature Imaging
                                in a Canine Brain Tumor Model
 [Not Available]

Anil Shetty1, Roger Price, Jon Schwartz, Rajesh Uthamanthil1, James Wang, Andrew Elliott1, John D. Hazle1, R Jason Stafford1

1The University of Texas M.D.Anderson Cancer Center, Houston, USA

A controlled minimally invasive alternative for brain tumor treatments is nanoshell mediated heating with intratumoral fiber placement. These particles are configured to preferentially absorb near-infrared (NIR) light and to emit heat through the process of surface plasmon resonance. Preferential damage was seen on the tumor side in a canine brain tumor model, with minimal damage in the contralateral normal brain. The tumor heated up to a higher lethal temperature (~18¢ªC), compared to the contralateral control side. These preliminary results prove the efficacy of these nanoshells to deliver lethal damage to the tumor in a minimally invasive manner.

                  1222.     Validation of Percutaneous MRI-Guided Laser Ablation with Real-Time MR Temperature Monitoring
                                 in a Canine Prostate Model
 [Not Available]

Anil Shetty1, Roger McNichols, Ashok Gowda, Sherry Klumpp1, Andrew Elliott1, Agatha Borne1, David Brammer1, John D. Hazle1, R Jason Stafford1

1The University of Texas M.D.Anderson Cancer Center, Houston, USA

The goal was to validate the efficacy of using a MR-registrable perineal template to percutaneously guide and execute multi-fiber laser treatment in a canine prostate model with real-time MR temperature monitoring. The maximum discrepancy between the actual signal void from the laser catheter and the center of the predicted trajectory was less than 1 mm. Real-time monitoring detected a maximum temperature rise of ~ 50 ¢ªC. This minimally invasive approach to laser ablation of tissue in the prostate  performed well, with a maximal positional error of less than 1 mm at an insertion depth of 6 cm.

                  1223.     Perfusion Calculation Based on MR-Temperature Maps and Focused Ultrasound Heating. Theoretical
                                 and Experimental Study

Iulius Dragonu1, Philippe Lourenço de Oliveira1, Christophe Laurent, 12, Baudouin Denis de Senneville1, Charles Mougenot, 13, Chrit Moonen1, Bruno Quesson1

1Laboratory for Molecular and Functional Imaging, Bordeaux, France; 2Saint André Hospital, Service de Chirurgie Digestive, Bordeaux, France; 3Philips Medical Systems, Suresnes, France

The objectives of the present work were to propose a method for quantitative estimation of perfusion rate, thermal diffusivity and energy absorption coefficients and to evaluate the pertinence of the bio-heat transfer equation (BHTE) to model the temperature distribution in presence of perfusion. Ex vivo kidneys were heated with HIFU under 3D thermometry, varying the input flow. Excellent concordance was observed between the theoretical description and the experimental results. This method allows for automatic determination of tissue thermal properties which influence the efficiency of thermotherapy in highly perfused organs.

                  1224.     Contribution of Temperature Dependent T1-Change, Slice Thickness and Positioning to an Artifact
                                 in Temperature Images of FUS Heating

Viola Rieke1, Kim Butts Pauly1

1Stanford University, Stanford, California , USA

The PRF-change with temperature is frequenctly used to monitor focused ultrasound (FUS) ablation. Because the heating area with FUS is small, partial volume effects are common. In addition, temperature dependend T1-changes can influence PRF based temperature measurements. In this work, we are investigating how partial volume effects, slice position, and temperature dependent T1-changes can influence PRF-based temperature measurements during FUS ablation.

                  1225.     Referenceless Multi-Coil Reconstruction

Viola Rieke1, Rexford Newbould1, Roland Bammer1, Kim Butts Pauly1

1Stanford University, Stanford, California , USA

Referenceless PRF thermometry estimates the phase due to a temperature rise in the heating region from the background phase and, therefore, does not need a baseline image for image subtraction. To estimate the background phase the phase images have to be smooth after phase unwrapping. We describe a phase reconstruction method for multi-coil acquisitions that prevents phase discontinuities to allow the combined images to be reconstructed with the referenceless method.

                   1226.     3D Navigated Real-Time Thermometry for Abdominal Imaging

Max Köhler1, Gregory Maclair2, Baudouin de Senneville2, Chrit Moonen2, Mario Ries2

1Philips Medical Systems, Finland; 2IMF, CNRS / Univ. Bordeaux2, Bordeaux, France

This work presents a combination of slice tracking combined with 2D image registration and look-up table based phase corrections for 3D navigated real-time MR-thermometry on abdominal organs.

                  1227.     Real-Time Correction of Respiratory-Induced Field Disturbances for PRFS-Based MR-Thermometry
                                in the Human Breast

Silke Hey1, Gregory Maclair1, Baudouin de Senneville1, Yasmina Berber1, Bruno Quesson1, Chrit Moonen1, Mario Ries1

1IMF, CNRS / Univ. Bordeaux2, Bordeaux, France

Real-time MR-thermometry based on the proton resonance frequency (PRF) technique allows monitoring of the local temperature evolution during radio-frequency, laser, cryogenics or focused ultrasound thermal ablation. Especially in the human breast, the presence of magnetic field fluctuations induced by the respiratory cycle can lead to thermometry artefacts if no correction is applied. For this purpose a look-up-table-based multi-baseline correction algorithm based on pencil-beam navigator data is applied to MR-thermometry to correct for the periodic B0-field changes. The feasibility of the correction method in real-time is demonstrated experimentally in a healthy volunteer using pencil-beam navigators for respiratory control.

                  1228.     A Hybrid PRF/T1 Pulse Sequence for Rapid, Simultaneous Temperature Tracking in Soft and Adipose
                                Tissues

Nick Todd1, Dennis L. Parker

1University of Utah, Salt Lake City, Utah, USA

Here we present a hybrid PRF/T1 pulse sequence capable of measuring those two temperature dependent parameters rapidly and simultaneously.  The PRF information is acquired in the usual, using a gradient echo sequence. The T1 information is extracted by varying the flip angle between consecutive scans and using the relation between signal intensity, T1 and flip angle.  This method allows the TR of the sequence to remain fixed, and keeps scan time short enough for real time temperature tracking.  Results from an oil/water heating experiment demonstrate the pulse sequences ability to monitor temperature changes in both water-based and fat-based substances.

                  1229.     Hot Spot Tracking for Focused Ultrasound Surgery of Liver Using Filtered Venography

Daisuke Kokuryo1, Etsuko Kumamoto2, Atsuya Okada3, Takamichi Murakami4, Susumu Fujii5, Toshiya Kaihara1, Kagayaki Kuroda6, 7

1Graduate School of Engineering, Kobe University, Kobe, Japan; 2Information Science and Technology Center, Kobe University, Kobe, Japan; 3The Center of Imaging Assisted Minimally Invasive Therapy, Iseikai Hospital, Osaka, Japan; 4School of Medicine, Kinki University, Sayama, Japan; 5Faculty of Science and Technology, Sophia University, Japan; 6Graduate School of General Science and Technology, Tokai University, Hiratsuka, Japan; 7Molecular Imaging Research Group, Institute of Biomedical Research and Innovation, Kobe, Japan

A target tracking technique using relative displacements of gravity points of cross sectional images of blood vessels was proposed to guide the ultrasound focus in the liver which moves with respiration. Experiments with healthy volunteer livers demonstrated that the average error of the target position estimation was within 3mm. The error was less than 4mm even with a position prediction process for considering time delay between the time points of position estimation and transducer setup. These results suggested that the proposed technique was sufficient for guiding the focus and hence the imaging slab position and orientation for the "self-reference" thermometry.

                  1230.     Temperature Monitoring with MURPS in a Reduced Field-Of-View

Mohammed Hassan Aljallad1, 2, Jing Yuan3, Magda Pilato3, Lawrence Patrick Panych3

1University of Massachusetts Lowell, Lowell, Massachusetts, USA; 2Brigham and Women's Hospital, Boston, Massachusetts, USA; 3Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA

MURPS was implemented for reduced field-of-view (rFOV) imaging using 2D RF excitation so that no additional time would be needed to acquire three MURPS slices compared to the time to acquire a single, full field-of-view slice without MURPS. 

                  1231.     Auto-Tracking Self-Reference Temperature Mapping During HIFU Transmission: Ex-Vivo Experiments
                                and Motion Simulations

Yu-Shun Wang1, Teng-Yi Huang1, Chih-Ching Wu2, 3, Hsu-Hsia Peng2, Wen-Shiang Chen, 34, Wen-Yih Isaac Tseng5

1National Taiwan University of Science and Technology, Taipei, Taiwan; 2National Taiwan University, Taipei, Taiwan; 3National Health Research Institutes, Taipei, Taiwan; 4National Taiwan University Hospital, Taipei, Taiwan; 5Medical College of National Taiwan University, Taipei, Taiwan

MR temperature mapping by proton resonance frequency (PRF) shift has been shown useful to monitor the treatment process of high-intensity- focused-ultrasound (HIFU) thermotherapy. However, the conventional reference subtraction method for temperature mapping has one major drawback. The accuracy of temperature mapping may be affected by tissue movement (e.g. respiration). To solve this problem, we proposed an alternative method which tracked the heating region automatically and estimated its background phase by applying 2D polynomial fitting. In this study, the proposed method was applied on ex-vivo porcine liver experiments. Moreover, simulated motion was added into the acquired image to test the efficiency of our method. The result shows our method is a robust and reliable method for temperature monitoring.

                  1232.     Analysis and Optimization of the IR-GRE Delayed Enhancement MRI Sequence Used for Imaging Post
                                RF Ablation Scars in the Posterior Wall of the Left Atrium

Sathya Vijayakumar1, 2, Eugene Gennaidy Kholmovski1, Nassir Marrousche1, Edward DiBella1

1University of Utah, Salt Lake City, USA

Radio Frequency (RF) ablation of posterior wall of the left atrium (LA) has become an accepted form of treatment for atrial fibrillations. Recently Delayed Enhancement MRI (DE-MRI) using an Inversion Recovery 3D Gradient Echo (IR-GRE) sequence has been proposed to visualize and assess the extent of post RF ablation scars in the LA. In this study, we analyze the performance of this sequence with respect to flip angles, inversion times and image contrast. The importance of phase images to distinguish scar and fat is also established.

                  1233.     Improved Precision of MR Temperature Mapping of Mobile Organs Using Magnetic Field Modeling

Gregory Maclair1, 2, Baudouin Denis de Senneville1, Mario Ries1, Bruno Quesson1, Pascal Desbarats2, Jenny Benois-Pineau2, Chrit Moonen1

1Laboratory for Molecular and Functional Imaging, Bordeaux, France; 2LaBRI, Talence, France

Real-time thermometry provides real-time temperature monitoring inside the human body and is an interesting tool to control interventional therapies based on thermal ablation. The PRF technique gives an estimate of temperature change at instant t by evaluating phase shifts between dynamically acquired images and reference data sets. The proposed approach for MR-thermometry consists in modeling the contribution of phase changes induced by respiratory motion in the abdomen during a learning step by assuming that demagnetization field changes can be approximated in first order with a linear term. Subsequently, during the intervention, the necessary phase reference maps are calculated in real-time.

                  1234.     Combining 2D RF Excitation, Parallel Imaging and UNFOLD in Focused Ultrasound Heating Experiment

Chang-Sheng Mei1, 2, J. Yuan2, B. Madore2, N. McDannold2, L. P. Panych2

1Boston College, Chestnut Hill, Massachusetts, USA; 2Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts, USA

In many clinical MRI-Guided Focused Ultrasound procedures, the focus is often much smaller than FOV. In addition, for acoustic wave to transfer to the ROI, there must be water in between the sonication source and the heated subject, resulting in even larger FOV and more scan time imaging unwanted region. To improve temporal resolution, we use technique that combines three different approaches at fast imaging: parallel imaging, UNFOLD and 2D RF excitation [3]. Results are shown in phase images where the FOV was fitted to a heated target, the FUS focus region, allowing temporal resolution to be increased by 8 fold.

                  1235.     A New Spectrum-Based Model for MR Thermometry

Xinyi Pan1, Cheng Li1, Kui Ying1

1Tsinghua University, Beijing, People's Republic of China

In this work, a novel spectrum based model is proposed for MR PRF thermometry. The new model describes the signal under temperature change accurately and can be solved by using a modern spectrum analysis algorithm ¨C the extended Prony method, which offers a good spectral resolution compared to conventional FFT analysis. With this model, the absolute temperature map can be obtained using a multi-echo GRE sequence without suffering from the disturbances caused by the fat component, inter-view motion and field drift. The results of phantom experiment are quite consistent with the real temperature measurement by the thermocouple probe.

                  1236.     Absolute Temperature Imaging with Non-Linear Fat/Water Signal Fitting

Kevin Michael Johnson1, Venkata Chebrolu1, Scott B. Reeder1

1University of Wisconsin - Madison, Madison, Wisconsin, USA

Previous work has shown improved absolute temperature mapping using fat as an internal reference in spectroscopic imaging in tissues that contain both water and fat. We propose a rapid method signal model based method for fat-water temperature mapping, capable of producing absolute temperature images with far fewer time points than spectroscopic method.  Evaluations in a fat/water phantom show excellent agreement with measurements made using a temperature probe.

                  1237.     Rapid MR Temperature Imaging Based on Model-Predictive Filtering of Undersampled Data

Nick Todd1, Ran Niu, Mikhail Skliar, Dennis L. Parker

1University of Utah, Salt Lake City, Utah, USA

Thermal therapies under MR guidance would benefit from an acceleration in the rate at which MR temperature maps are acquired.  For procedures that induce rapid tissue heating, current MR techniques to monitor temperature cannot simultaneously provide adequate temporal resolution, spatial resolution and FOV coverage.  We present an algorithm that combines thermal model predictions with undersampled k-space data to reconstruct accurate temperature maps.  When applied to proton resonance frequency (PRF) data, accurate temperature maps are created using one-sixth of the full measurement data.  Reducing the number of acquired k-space lines allows for faster scan times, greater volume coverage or higher spatial resolution.

                  1238.     Cramer-Rao Lower Bound for Model-Based PRF Temperature Mapping

Cheng Li1, Xinyi Pan1, Kui Ying1

1Tsinghua University, Beijing, People's Republic of China

In this work, the expression for Cram¨¦r-Rao Lower Bound (CRLB) for model based PRF Temperature mapping is derived by exploiting the characteristic that the temperature estimation intrinsically is a frequency difference estimation of damped complex exponential signal. With the CRLB, the noise performance of two algorithms to estimate the temperature, Prony algorithm and LM algorithm based on ML criterion, is evaluated and compared. By investigating the CRLB dependence on the imaging SNR, number of echoes, echo times, fat/water ratio, the choice of imaging parameters is discussed. The CRLB analysis theoretically provides insight into how the imaging parameters and estimation algorithm affect the noise performance in temperature mapping.

                  1239.     Preclinical Testing of a Second-Generation MRI-Guided Focused Ultrasound System for Transcranial
                                Brain Tumor Ablation

Nathan McDannold1, Eyal Zadicario2, Magdalini Pilatou1, Ferenc Jolesz1

1Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts, USA; 2InSightec, Haifa, Israel

This work tested the performance of a second-generation focused ultrasound device developed for noninvasive thermal ablation of brain tumors. Tests were performed using cadaver skulls and tissue-mimicking phantoms. MRI-based thermometry was used to evalu-ate the focal heating during high-power sonications (for ablation), lower power sonications (to verify the focal point localization), and heating adjacent to the skull bone. The device, which uses cavitation-enhanced heating, expanded the range of targetable regions in the brain and increased the ratio between focal heating and skull-induced heating. This ratio was 15.6±5.6 when cavitation was evident and 1.6±0.8 when it was not.

                  1240.     MR Acoustic Radiation Force Imaging: Comparison of Encoding Gradients

Jing Chen1, 2, Ron Watkins1, Kim Butts Pauly1

1Stanford University, Stanford, California , USA

MR acoustic radiation force imaging (MR-ARFI) is a novel method toguide HIFU interventions. It measures the tissue displacement inducedby the acoustic radiation force, which is most suitable forapplications with little temperature elevation. In this work, threedifferent gradient sets for displacement encoding are implemented andcompared for MR-ARFI. By using the repeated bipolar gradients, thenonlinear background phase was reduced, and the SNR was significantlyenhanced. Displacement on the order of submicrons could be detectedwith the improved encoding gradients.

                  1241.     Monitoring of HIFU Treatment Effectiveness by MR Imaging: Advantage of the Magnetization Transfer
                                 Ratio Over the Thermal Dose as Evidenced by Overheating Experiments

Hsu-Hsia Peng1, Teng-Yi Huang2, Hsiao-Wen Chung1, Chih-Ching Wu1, Wen-Shiang Chen3, Wen-Yih Isaac Tseng4

1National Taiwan University, Taipei, Taiwan; 2National Taiwan University of Science and Technology, Taipei, Taiwan; 3National Taiwan University Hospital, Taipei, Taiwan; 4Medical College of National Taiwan University, Taipei, Taiwan

We performed a deliberately designed overheating HIFU treatment experiment where tissues were heated over 100 °C, to investigate the use of the magnetization transfer ratio (MTR) for evaluation of treatment extent in the presence of boiling-induced air bubbles and the consequent susceptibility artifacts. The thermal dose as conventionally used to estimate cell damage failed to outline the heated areas reliably, whereas the MTR measured after termination of HIFU treatment correctly indicate the heated extents. Geometrical consistency between MTR maps and optical images of the heated spot suggests the importance of simultaneous measurements of temperature and MTR changes for HIFU heating.

                  1242.     Acute and Chronic Magnetization Transfer Ratio Observations in Canine Cryoablation

Andrew B. Holbrook1, 2, Sonal Josan1, Donna M. Bouley1, Bruce Daniel1, Kim Butts Pauly1

1Stanford University, Stanford, California , USA

MR-guided cryoablation is a promising minimally invasive treatment of prostate cancer.  However, it is not clear what images acquired after ablation provide in terms of tissue assessment.  Besides contrast-enhanced (CE) imaging, magnetization transfer (MT) imaging is a potential way of assessing tissue in-vivo.  Cryolesions were created in three canines, each imaged three times over 2-3 weeks with MT and CE protocols before being euthanized for histological analysis.  MT contrast could be seen immediately and persisted throughout the chronic experiment, even as hemorrhage decreased and the lesions changed.  MT contrast could complement CE imaging for assessing the prostate as it heals.

                 1243.     MRI-Guided Cryoablation - Acute Cryolesion Assessment with T1, T2 Imaging

Sonal Josan1, Maurice van den Bosch1, Jarrett Rosenberg1, Bruce Daniel1, Kim Butts Pauly1

1Stanford University, Stanford, California , USA

MRI guided cryoablation is a promising minimally invasive therapy for prostate tumors. Contrast enhanced(CE), DWI and MT images can be used to predict the extent of tissue necrosis. The purpose of this work was to evaluate the appearance of the acute canine prostate cryolesion on conventional T1 and T2 weighted images, and compare those to the CE images. The signal enhancement on T2w images was correlated to the freeze area, and the lesion boundaries on T1 and T2 images were compared to the CE lesion.

 

B0 Inhomogeneity Correction (Global/Local)

Hall D                                   Monday 14:00-16:00  

                 1250.     Multiple Resonant Frequency Offset Acquisitions for Imaging of Metallic Implants

Kevin M. Koch1, R F. Busse2, T A. Lewein1, H G. Potter3, R S. Hinks1, K F. King1

1GE Healthcare, Waukesha, Wisconsin, USA; 2GE Healthcare, Madison, Wisconsin, USA; 3Hospital for Special Surgery, New York, New York, USA

Most metallic implants used in bone and joint arthroplasty induce severe spatial perturbations to the B0 magnetic field utilized in MR. These perturbations distort slice-selection and frequency encoding techniques utilized in conventional 2D MR imaging and tremendously hinder MR diagnosis of complications from arthroplasty.   A method is presented whereby multiple 3D fast-spin-echo images are collected using discrete offsets in RF transmission and reception frequency.  It is demonstrated that these images can be combined into a composite image that is devoid of slice-plane distortion and possesses greatly reduced distortions in the readout direction, even in the immediate vicinity of metallic implants.

                  1251.     Dynamic Compensation of B0 Field Inhomogeneities Restores Complex FMRI Time Series Activation
                                 Power

Andrew David Hahn1, Andrew S. Nencka1, Daniel B. Rowe1

1Medical College of Wisconsin, Milwaukee, USA

Fluctuations in the main magnetic field (B0) often occur during fMRI experiments as a result of subject respiration or motion.  The effect is temporal noise in both the magnitude and phase, which can reduce the significance of statistical tests for functional activity.  If a single image in a time series is chosen as a reference, all other images in the series can be corrected using their inherent phase information such that the B0 field offset at each acquisition point is time invariant.  This reduces or removes effects of temporal variations in B0 homogeneity, providing higher quality fMRI time series. 

                  1252.     Towards Parcellated Dynamic Shimming

Michael Poole1, Richard Bowtell1

1University of Nottingham, Nottigham, UK

The need for a homogeneous magnetic field in MRI is well established, especially at high static magnetic field strengths where susceptibility-induced image distortions and signal losses become excessively large. Dynamic shim updating has been shown to improve magnetic field homogeneity to a greater extent than conventional whole volume shimming. Previous work showed by simulation that the magnetic field inhomogeneity can be further reduced if shimming is performed over a series of compact, cuboidal sub-volumes. In this work we corroborate the simulated results with experimental data obtained at 7T and demonstrate a fast, robust automatic field mapping and shim calculation routine.

                  1253.     Dynamic B0 Shimming in the Heart at 3T

Jeff A. Stainsby1, Venkat Ramanan2, Graham A. Wright2

1GE Healthcare, Toronto, Canada; 2Sunnybrook Health Sciences Centre, Toronto, Canada

Dynamic shim updating has been recently demonstrated to provide benefit in neuro applications. This study investigates the feasibility of performing dynamic shim updates as a function of both spatial location and cardiac phase in cardiac imaging at 3T. Dynamic shim updating was shown to reduce the mean frequency offset across multiple slices and cardiac phases from 28.5Hz to 2.3Hz and in-plane linear field variations from –3.35 and 3.05Hz/cm to –0.19 and 1.15Hz/cm respectively.

                  1254.     Sense Shimming (Sensh); a Fast Approach for Determing Field Inhomogeneities Using Coil Sensitivity
                                 Information

Daniel Nicolas Splitthoff1, Maxim Zaitsev1

1University Hospital Freiburg, Freiburg, Germany

The pursuit for ever higher field strengths and faster data acquisitions has led to the construction of coil-arrays with high numbers of elements. With the SENSE approach, it has been shown by Pruessmann et al., how the sensitivity of those elements can be used for image encoding. We will here present a proof of principle of a method which can be considered a special case of the SENSE method and completely abstains from using encoding gradients. The FID data thus obtained can be used for determining field inhomogeneities; the method has therefore been termed SENSH for SENsitivity Shimming.

                   1255.     Dependence of the View-Angle-Tilting Technique on the Slice Orientation Angle in Correcting
                                  Susceptibility Artifacts

Kwan-Jin Jung1, 2, Chan-Hong Moon2, Hua Peng1

1Univ. of Pittsburgh & Carnegie Mellon Univ., Pittsburgh, Pennsylvania, USA; 2University of Pittsburgh, Pittsburgh, Pennsylvania, USA

The view-angle-tilting (VAT) technique has been known to be effective in correcting the susceptibility artifacts in slice selective MR imaging. However, it has been discovered that VAT works only when the slice orientation is orthogonal to the longer axis of the object with susceptibility. This discovery has been theoretically analyzed and confirmed by computer simulation and experimentation at 3T on a phantom and a human head.

                  1256.     Correction of Susceptibility Artifacts in Slice Selective MR Imaging at a Specific Slice Orientation Angle

Kwan-Jin Jung1, 2, Chan-Hong Moon2

1Univ. of Pittsburgh & Carnegie Mellon Univ., Pittsburgh, Pennsylvania, USA; 2University of Pittsburgh, Pittsburgh, Pennsylvania, USA

The effects of susceptibility in slice selective MR imaging include slice offset in the slice direction, and the readout shift in the readout direction. When the projection of the slice offset onto the readout axis has the same length as the readout shift but with an opposite polarity, the geometric shift is corrected on the reconstructed image. This correction condition is met when the slice orientation is made oblique to the longer axis of the object with susceptibility by an angle of arctan(GS/GR). This discovery has been theoretically analyzed and confirmed by a computer simulation and experiments at 3T on a phantom and a human head.

                  1257.     Inhomogeneity Correction at 7 Tesla Using Masked Mean Filtering of Fast and Low Resolution Gradient
                                Echo Reference Data

Michael Schildt1, 2, Kai Zhong2, Klaus Dietz Tönnies2, Oliver Speck2

1Leibniz-Institute for Neurobiology, Magdeburg, Germany; 2"Otto von Guericke" University, Magdeburg, Germany

High resolution and high contrast T1 images are widely used as anatomical reference for functional imaging studies. The anatomical information is obtained from 3D gradient echo data (e.g. MPRAGE). Typically, images acquired at high field strength of 7 Tesla suffer from severe B1 inhomogeneity resulting in erroneous segmentation due to strong intensity variation of voxels representing similar tissue (e.g. brain gray or white matter). In this study fast and low resolution gradient echo reference data with minimal intrinsic contrast are used to estimate the B1 inhomogeneity by masked mean filtering and correspondingly correct the MPRAGE intensity variation.

                   1258.     Reduction of Artifacts in Susceptibility Weighted Imaging

Zhaoyang Jin1, 2, Ling Xia2, Yiping Peter Du3

1Hangzhou Dianzi University, Hangzhou, People's Republic of China; 2Zhejiang University, Hangzhou, People's Republic of China; 3University of Colorado Denver School of Medicine, Denver, Colorado , USA

In susceptibility weighted imaging, sub-optimal selection of the size of low-pass filter results in large residual background phase in the phase mask in regions with severe field inhomogeneity and artifacts in the susceptibility weighted images. The minimum-intensity projection (mIP) can also cause signal loss in peripheral regions of the brain. In this study, we demonstrate the dependency of the severity of artifacts in the phase mask on the size low-pass filter. We also present a volume-segmented mIP approach to eliminate the signal drop-off in peripheral region of the brain.

 

High Field Imaging Methods

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  1328.     Double Inversion Recovery MRI with Fat Suppression at 3T and 7T

Guillaume Madelin1, Matilde Inglese1, Niels Oesingmann2

1New York University, New York, New York, USA; 2Siemens Medical Solutions USA, New York, New York, USA

Double Inversion Recovery (DIR) MRI combines two inversion pulses in order to simultaneously suppress signals from tissues with different T1 relaxation times. In the brain, DIR allows to selectively image gray matter (GM) by nulling the signal from white matter and cerebrospinal fluid at the time of the excitation pulse. Imaging GM structures is important in the study of many neurological disorders such as Alzheimer's disease, epilepsy and multiple sclerosis. This study demonstrates the feasability of 2D and 3D DIR MRI with chemical shift fat inversion recovery (csFatIR) at 3T and 7T.

                 1329.     Comparison of BSSFP and GRE at 9.4 Tesla

Joseph S. Gati1, L Martyn Klassen1, Ravi S. Menon1

1Robarts Research Institute, London, Canada

Balanced steady-state free precession (bSSFP) pulse sequences have found widespread use at clinical field strengths because of short acquisition times, unique contrast and increased signal to noise characteristics compared to similarly acquired gradient-recalled echo (GRE) methods. To date there has been no published demonstration of the advantages of bSSFP over GRE at an ultrahigh magnetic field strength that quantifies the advantages in vivo. This study performs the simple task of comparing signal to noise ratio and contrast in optimized bSSFP images versus acquisition matched GRE images in mouse brain at 9.4 T.

                  1330.     Progress in 3d Imaging at 4 T with SWIFT

Curtis Andrew Corum1, Djaudat Idiyatullin1, Steen Moeller1, Michael Garwood1

1University of Minnesota, Minneapolis, Minnesota, USA

We demonstrate high resolution T1 and proton density weighted imaging in human brain with SWIFT at 4 T. SWIFT has several unique properties. The gradient updating is very sooth so SWIFT is quieter, even than quiet radial sequences. The data can be motion corrected, similar to PROPELLER or other radial sequences, and further is immune to other common gradient based errors such as incidental phase encoding.SWIFT is 40dB quieter than equivalent fast cartesian 3d GRE imgaing sequences. We report our progress in SWIFT at 4 T for human brain imaging and look forward to developing SWIFT's potential for T1 and PD pediatric neuroimaging.

                  1331.     High Resolution T2* Weighted Reverse and Forward Spiral Imaging at 7Tesla

Peter Börnert1, Wouter M. Teeuwisse2, Holger Eggers1, Mark A. van Buchem2, Matthias JP van Osch2

1Philips Research Europe, Hamburg, Germany; 2Leiden University Medical Center, Netherlands

High resolution spiral imaging could find an interesting application in ultra-high field imaging. Reverse and long TE forward spiral imaging providing strong T2* weighting are of interest for susceptibility weighted imaging showing high anatomical detail. In this work, the basic applicability of forward and reverse spiral imaging at 7T is investigated with respect to performance, necessary corrections and contrast properties. In-vivo results are shown and discussed underlining the great potential of spiral sampling at 7T.

                  1332.     Oh No, Where Did My Contrast Go? - Righting the Shameful Wrong About SE T1 Contrast at High Field

Roland Bammer1, Anne Marie Saywer1, Jung Jiing Hsu1, Gary H. Glover1, Rexford David Newbould1

1Stanford University, Stanford, California , USA

Over the last few years concerns have been raised about lacking contrast in SE T1-weighted sequences. Specifically, 3T’s ability to provide adequate GM/WM contrast in the brain and spine was criticized. Nevertheless, it is well known that the T1 relaxation times of semi-solid tissue will increase with field strength, whereas T1 of CSF as well as T2 relaxation times remain almost unchanged across B0. Recently, it was even shown that T1 dispersion in brain tissue increases with increasing B0. T1 prolongation and dispersion actually benefit T1w imaging. The objective of this study was therefore to determine the optimal T1 contrast at 1.5T, 3T, and 7T and to find out whether or not there is truly a loss in tissue contrast with increasing B0.

                  1333.     Optimization of HyperTSE at 7T for Efficient T2-Weighted Imaging

Oliver Speck1, Matthias Weigel2

1Otto-von-Guericke-University, Magdeburg, Germany; 2University Hospital, Freiburg, Germany

The high SNR achievable at 7T can be utilized to increase the spatial resolution of morphologic T2-weighted images. However, the very high RF-power requirements can dramatically limit the efficiency of multi-spin-echo methods (TSE). HyperTSE has been proposed to reduce SAR without compromising image quality. We demonstrate that with further optimization of the RF-pulses and the flip angle variations, T2-weighted imaging at 7T with high resolution and high volume coverage is feasible without increased scan times due to SAR limitations. Without prolongation of the pulse lengths a four-fold improvement in temporal efficiency compared to a standard TSE implementation is possible.

 

EPI - Corrections

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  1362.     Ghost Reduction for Oblique EPI Using Entropy Based Compensation of Phase Encoding Blips

Magnus Mårtensson1, 2, Anders Nordell1, 2, Bo Nordell1, 2, Stefan Skare3

1Karolinska University Hospital, Stockholm, Sweden; 2Karolinska Institute, Stockholm, Sweden; 3Stanford University, Stanford, California , USA

A new sequence has been developed to be used as a calibration scan with an altering compensation blip factor for phase encoding, followed by an entropy calculation to find the best compensation blip factor. This method can be used both with single and multi-shot EPI sequences with equally good ghost reduction. Using this calibration scan for each scan plane angle in the exam is a robust technique that results in a major improvement of ghosting artifact suppression for oblique EPI scans. The presented method has great potential when implemented in oblique EPI such as fMRI, DWI, PWI and cardiac imaging.

                  1363.     Ghost Reduction for Oblique EPI Using Entropy Based Regridding

Magnus Mårtensson1, 2, Mathias Engström1, 2, Bo Nordell1, 2

1Karolinska University Hospital, Stockholm, Sweden; 2Karolinska Institute, Stockholm, Sweden

In oblique EPI acquisitions data is sampled in a Cartesian coordinate system, but phase offsets, due to system time delays and eddy currents, will cause the phase encoding lines to be non-equidistantly separated, resulting in non-Cartesian data and thus ghosting. This study proposes a non-Cartesian approach for Cartesian data sets, using entropy calculations to regrid data in order to reduce ghosting artifacts.

                  1364.     Phase and Amplitude Correction in Bipolar Multi-Gradient-Echo Water-Fat Imaging

Holger Eggers1, Peter Koken1, Peter Boernert1

1Philips Research Europe, Hamburg, Germany

Gradient system and receive coil imperfections give rise to differences in phase and amplitude between the signal from odd and even echoes in bipolar multi-gradient-echo imaging. A reliable water-fat separation with generalized multi-point Dixon methods based on data from such acquisitions requires a suitable compensation for these imperfections. In this work, a spatially resolved estimation and subsequent correction of phase and amplitude errors is suggested. It is demonstrated to substantially reduce artifacts in whole-body water-fat imaging with continuous table movement.

                  1365.     Multiple-Channel EPI Phase Correction for SENSE Based Image Reconstruction

Fred J. Frigo1, Sangwoo Lee1, R. Scott Hinks1

1GE Healthcare, Waukesha, Wisconsin, USA

Inherent in the data collection scheme for Echo Planar Imaging (EPI) are phase errors that lead to image artifacts when left un-corrected.  One method for reducing phase errors is to use the nearest-neighbor EPI phase correction approach.   For SENSE based image reconstruction, the phase characteristics between channels must be preserved after EPI phase correction.  The proposed method of applying nearest-neighbor EPI phase correction for each spatial location and each channel provides a robust and highly effective phase correction technique for SENSE based EPI that can accommodate double oblique scan geometries and has demonstrated excellent image quality.

                  1366.     New Algorithm of Correction for Eddy Current-Induced Distortion of DWI  [Not Available]

Yung-Chin Hsu1, Ching-Han Hsu1, Wen-Yih Isaac Tseng2

1National Tsing Hua University, Taiwan; 2National Taiwan University College of Medicine and Hospital, Taiepi, Taiwan

In DWI, diffusion gradients usually incur residual eddy currents which lead to gross geometry distortions. Previous retrospective methods usually assume the deformation field is linear which may not be true for high b-value DWI images. In the present study, we propose a generalized algorithm incorporating with two DWI images which are acquired with opposite diffusion gradients. With this algorithm, higher order of the deformation field can be taken into consideration. The proposed method is applicable to DSI or QBI dataset where high b-value is used and data points are symmetric about the origin in the q-space.

 

Relaxometry & Quantitation

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                 1409.     Interpolated Estimates of Magnitude, R2*, and Frequency Offset in SS-PARSE Imaging

Weidong Tang1, Stanley J. Reeves1, Donald B. Twieg2

1Auburn University, Auburn, Alabama, USA; 2University of Alabama at Birmingham, Birmingham, Alabama, USA

This paper proposes a new reconstruction method for single-shot parameter assessment by retrieval from signal encoding (SS-PARSE). The cubic convolution interpolation is used to reconstruct higher resolution images with limited data from short read-out time. A polynomial approximation is suggested to address the problematic exponential time function in SS-PARSE model. By this approximation, reconstruction algorithm based on conjugate-gradients can be accomplished by FFTs. Results with this method show sharper edges and smoother reconstructions in areas known to be smooth.

                  1410.     Derivation of Optimal Flip Angles Via Minimization of Noise Factor Over Large Range of T1 for Accurate
                                 Variable Flip Angle-Derived T1 Estimations

Keiko Miyazaki1, David J. Collins1, Dow-Mu Koh1, David J. Hawkes2, Martin O. Leach1, Matthew R. Orton1

1Institute of Cancer Research, Sutton, UK; 2University College London, London, UK

The variable flip angle method allows relatively accurate estimation of T1 in a short time period compared to lengthy inversion recovery methods. Here, we propose a simple and efficient method of obtaining the optimal pair of flip angles which would enable accurate T1 estimations in a sample with a large T1 range by using an optimization scheme. This is of great importance in numerous areas in MRI, particularly in DCE-MRI studies where accurate determination of T1 is crucial in obtaining quantitative parameters which are widely used to monitor disease progression and regression.

                 1411.     Measuring T2 and T2' in the Brain at 1.5T, 3T and 7T Using a Hybrid Gradient Echo-Spin Echo Sequence
                                and EPI

Eleanor F. Cox1, Penny A. Gowland1

1University of Nottingham, Nottingham, UK

T2 and T2¢ was measured in the brain at 1.5, 3 and 7T using a gradient echo-spin echo (GESE) sequence and T2 was also measured with single shot SE-EPI. Both sequences were used to measure values of T2 in grey (both frontal and occipital) and white matter in four healthy volunteers at all three field strengths. Inverse T2 contrast was seen in the occipital region of the brain. The T2 values measured agreed with previously published data and the GESE sequence was calibrated against SE-EPI results using phantoms.

                  1412.     Measuring T2 and T1 Simultaneously in the Abdomen Using T2-Prepared BTFE at 3T

Eleanor F. Cox1, Caroline L. Hoad1, Penny A. Gowland1

1University of Nottingham, Nottingham, UK

It is possible to measure T2 and T1 simultaneously using a T2-prepared balanced turbo field echo sequence (T2-prep bTFE) which has particular application in the abdomen at 3T. The T2-prep bTFE sequence was calibrated against EPI using gel phantoms and was then used to measure T2 and T1 in the kidneys, liver and spleen. The results were comparable to previously published results using spin echo and inversion recovery FSE. The ability to measure T2 and T1 in a reasonable time has important applications in studying changes of gastrointestinal (GI) contents, such as viscosity and dilution, in the GI tract.

                 1413.     B1 Insensitive Saturation Recovery T1 Measurements at 3 Tesla Using Water Suppression Enhanced
                          Through  T1 Effect (WET) Saturation Pulse

Frederic Courivaud1, 2, Henrik B.W. Larsson3, 4

1Philips Medical Systems, Oslo, Norway; 2Rikshospitalet, Oslo, Norway; 3Glostrup Hospital, University of Copenhagen, Copenhagen, Denmark; 4Norwegian University of Science and Technology (NTNU), Trondheim, Norway

Quantitative measurements of MR relaxation properties (T1 and T2) are relevant parameters for diagnosis and prognosis of various diseases. T1 measurement is particularly important in the development of T1-based contrast enhanced perfusion measurements. However, most of T1 measurements methods at high field require B1 mapping correction before signal analysis. We demonstrate here the use of optimized four-pulse Water suppression Enhanced through T1 effects (WET) for B1 insensitive saturation recovery T1 measurements at 3T, without the use of B1 mapping. T1 values in accordance with published results and WM/GM segmentation of the brain are shown.

                  1414.     Lipid T2* Determination by Modeling the Intra-Molecular Chemical Shift Effect

Christian Graff1, Eric Clarkson1, Kenneth L. Weiss2, Maria I. Altbach1

1University of Arizona, Tucson, Arizona , USA; 2University of Cincinnati, Cincinnati, Ohio, USA

T2* measurements are important for the quantification of physiological events or pathologies related to susceptibility changes in tissue. When fat is present, the T2* signal decay is modulated by the chemical shift of the various hydrogen types that make up the fat molecule leading to improper T2* estimation. In this work we present a signal equation model for extracting T2* for fat, minimizing the effects of the intra-molecular chemical shift.

                  1415.     Magnetization Transfer Effect on T2 Measurement Using Steady-State Free Procession

Zhongliang Zu1, Yanming Yu1, Qi liu1, Xuna Zhao2, Min Chen3, Shanglian Bao1

1Peking University, Beijing, People's Republic of China; 2Philips MRI Center, Beijing, People's Republic of China; 3Beijing Hospital, Beijing, People's Republic of China

DESPOT2 is a rapid T2 mapping technique based on acquisition of a pair of or several SSFP images and prior knowledge of T1. However, recent research has reported that in biological tissues the steady-state signals of SSFP deviate from theoretical predictions based on Bloch equations, which could be attributed to magnetization transfer (MT). Therefore, the accuracy of DESPOT2 is doubted. We analysed the MT effect on T2 measurement. Optimized imaging parameters were proposed to avoid the MT effect on T2 mapping.

                  1416.     Towards Online Reconstruction of Quantitative Magnetization-Transfer Imaging

Dirk K. Müller1, Thies H. Jochimsen1, Torsten Schlumm1, Harald E. Möller1

1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

A challenging aspect of quantitative magnetization-transfer (qMT) is the complex model describing a solid and a semi-solid pool exchanging magnetization, causing long scanning times and difficult post processing. We present a fast fitting algorithm for qMT imaging which greatly reduces post-processing times. Based on the model of Ramani, a combination of brute force and Levenberg-Marquardt algorithms leads to a dramatic reduction of processing times which could eventually be used for online reconstruction in future clinical applications.

                  1417.     Magnetic Field and Age Dependence of the Distribution of the Longitudinal Relaxation Time in the
                                Living Human Brain

Ana-Maria Oros-Peusquens1, Maija Laurila1, N. Jon Shah1

1Institute of Medicine, Research Centre Juelich, Juelich, Germany

We report the results of a 12-volunteer study on the mapping of the T1  relaxation time at 1.5T, 3T and 4T and its field and age dependence. Three nearly identical whole-body scanners have been employed, operating at field strengths of 1.5T (Siemens Avanto), 3T (Siemens Trio) and 4T (Siemens/Bruker MedSpec). Close to whole-brain T1 mapping was performed using TAPIR, a sequence based on the Look-Locker method, which uses an interleave of slice and time point read-outs for fast multi-slice acquisition whilst maintaining good temporal resolution. The whole-brain histogram of T1 values was fitted using a superposition of three Gaussian distributions. The dependence of the centroids of the WM and GM peaks on field strength was investigated and compared to empirical formulae by Bottomley or Fischer. The age dependence of the centroids was also investigated; no clear behaviour was observed for the WM; a clear decrease of the T1 of GM was found at all three fields.

                  1418.     Estimation of the Inversion-Pulse Efficiency in the Context of Multi-Exponential Analysis of Spin-Lattice
                                 Relaxation

Christian Labadie1, 2, Jing-Huei Lee3, Harald E. Möller4

1Max Planck Institute  for Human Cognitive and Brain Science, Leipzig, Germany; 2University of Leipzig, Leipzig, Germany; 3University of Cincinnati, Cincinnati, USA; 4Max Planck Institute for Human Cognitive and Brain Science, Leipzig, Germany

A CONTIN-based procedure to estimate the inversion-pulse efficiency in the context of multi-exponential longitudinal relaxation is proposed and compared to a mono-exponential three-parameter NLLS fit.  Simulations using continuous T1 distributions show that the three-parameter NLLS fit underestimates the efficiency when a small T1 peak is present below 400 ms.  Such underestimation of the efficiency is apparent in the white matter of the human brain at 4 Tesla.  The novel procedure enables to adequately estimate the inversion-pulse efficiency necessary to perform a reliable multi-exponential analysis of spin-lattice relaxation. 

                  1419.     Ultrashort T2* Relaxometry Using Conventional Multiple Gradient Echo Sampling with S0 Fitting:
                                Validation with Quantitative UTE (QUTE) Imaging

Peter Roland Seevinck1, Clemens Bos2, Chris J.G. Bakker1

1University Medical Center, Utrecht, Netherlands; 2Philips Medical Systems, Best, Netherlands

To quantify ultrashort T2* components associated with the increasing interest in high field MR as well as in (super-)paramagnetic contrast agents (iron-oxide or holmium), we propose a post-processing methodology, based on the incorporation of S0 (S at t=0ms) in the fitting algorithm, which is generally applicable for T2* relaxometry and does not increase scan time. Sub-millisecond T2* species introduced by holmium-loaded microspheres in gel and ex vivo rabbit liver were assessed qualitatively and quantitatively using S0-fitting and results were compared to quantitative UTE. S0-fitting is accurate and time efficient and therefore suitable for in vivo studies.

                  1420.     Modeling the Role of Membrane Permeability and T2 Relaxation TE-Dependent Signal Decay

Kevin Harkins1, Jean-Philippe Galons1, Timothy Secomb1, Theodore Trouard1

1University of Arizona, Tucson, USA

The presence of compartmental T2 differences in tissue has been discount due to the experimental measurement of monoexponential T2 decay in tissue. To assess the role of exchange, T2 relaxation and noise on fitting of signal decay, we have developed a finite element model consisting of square cells separated from extracellular space by a permeable membrane.  In the presence of physiological membrane permeability and reasonably high SNR, tissues with considerably different T2 relaxation times in the intra and extracellular spaces can exhibit monoexponential behavior.

                  1421.     Determining Precision of Relaxation Time Measurements: Application to T2 Mapping

Julien Sénégas1, Clemens Bos2, Hannes Dahnke1

1Philips Research Europe, Hamburg, Germany; 2Philips Medical Systems, Best, Netherlands

Usually, reproducibility of relaxation time mapping is assessed, by comparing relaxation time values across regions of interests in multiple patients. However, generally, little is known on the precision of the individual experiment performed in a specific subject. Here, a maximum likelihood method is presented that calculates a map of the relaxation time standard deviation, from a single mapping experiment, accounting for the noise level of the input images and the sequence parameters. The proposed method was evaluated in simulations and in vivo in T2 mapping of the knee. Knowing the relaxation time standard deviation, the significance of (localized) relaxation time changes over experiments can be more precisely stated.

                  1422.     Evaluation of Parameter Estimation Methods for T2* Relaxometry: A Monte Carlo Approach

Matthew T. Latourette1, James E. Siebert1

1Michigan State University, East Lansing, Michigan, USA

T2* relaxometry gains increasing importance with its new clinical role measuring regional iron concentrations for managing iron overload patients.  Using Monte Carlo simulations, this study evaluates the performance of five methods for parameter estimation for T2* quantitation from multi-echo gradient echo data.  The simulations show that nonlinear least squares fitting of data corrected by SCÖ|S2-2ς 2| and maximum likelihood estimation provide the most accurate and precise results. Earlier literature R2* values published for clinical decision thresholds can still be used. Caution should be given for results based upon methods with bias and higher variance especially when number of subjects is small.

                  1423.     WAter Saturation Shift Referencing (WASSR) for Chemical Exchange Saturation Transfer Experiments
 [Not Available]

Mina Kim1, 2, Joseph Gillen, 2, Jinyuan Zhou, 2, Peter Christiaan van Zijl, 2

1, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; 2Kennedy Krieger Institute, Baltimore, Maryland, USA

Chemical exchange saturation transfer (CEST) imaging exploits exchange-based magnetization transfer (MT) between solute and water protons. CEST measurements generally require an asymmetry analysis of the water saturation spectrum (Z-spectrum) with respect to the water frequency, a process exquisitely sensitive to magnetic field inhomogeneities. We show that direct water saturation images acquired with a brief low-power RF saturation pulse can be used to measure the precise water frequency in each voxel, allowing proper centering of Z-spectra independent of spatial B0 variations. After validation in a phantom, the approach is demonstrated in vivo to detect glycogen in human muscle at 3T.

                  1424.     Quantitative MT Measurement - is 3T the Solution or the Problem?

Mara Cercignani1, 2, Daniel C. Alexander2, Rebecca S. Samson2, Mark R. Symms2, Gareth J. Barker3

1Fondazione Santa Lucia, Roma, Italy; 2UCL, London, UK; 3Institute of Psychiatry, KCL, London, UK

Here, we address the design of an optimal acquisition protocol for quantitative MT at 3.0T, and assess the performances of this technique at 1.5T and at 3.0T. This involves selecting the most appropriate acquisition parameters, such as TR and flip angle, as well as the optimal sampling scheme, under some field strength dependant constraints. We compare 3 acquisition protocols (2 at 3T and 1 at 1.5T) performing a formal analysis of advantages and limitations of higher field strength using both numerical simulations and real data, in order to determine whether the SNR benefits at 3T outweigh the disadvantages.

                  1425.     Investigating the Dependence of R2* of Whole Blood on Oxygenation, Contrast Agent Concentration
                                and Magnetic Field Strength

Nicholas P. Blockley1, Alexander G. Gardener1, Susan T. Francis1, Penny A. Gowland1

1University of Nottingham, Nottingham, UK

The relaxation properties of blood are key to many functional MRI techniques. The transverse relaxation rate, R2*, is of particular relevance to BOLD imaging and MR angiography. In this work we investigate the dependence of R2* on the oxygenation and the concentration of ProHance contrast agent in whole blood. The variation of R2* with contrast agent concentration was non linear. These experiments were performed at field strengths of 1.5T, 3.0T and 7.0T allowing the trends in relaxivity as a function of magnetic field strength to be studied.

                  1426.     Investigating the Dependence of R1 and R2* of Gadofosveset Concentration and Magnetic Field Strength

LEI JIANG1, Nicholas Blockley1, Catherine Ludman2, Sue Francis1, Penny Gowland1

1University of Nottingham, Nottingham, UK; 2Nottingham University Hospital NHS Trust, Nottingham, UK

The relaxation properties of blood are key to many MRI techniques. In this work we measure the R1 and R2* relaxivities of a blood pool contrast agent Gadofosveset (Vasovist™, Schering) in whole human blood at 37oC at 1.5 T, 3.0 T, and 7.0 T. We found that the R1 relaxivity reduced with field strength. The R2* relaxivity was non linear, but showed greater sensitivity to contrast agent concentration at higher field strength.

                  1427.     Investigation of Water Diffusion Effect on the Signal Relaxation in Presence of a Stochastic Cylinder
                                 Network: A Phantom Study

Maja C. Sohlin1, Jan Sedlacik2, Jürgen R. Reichenbach2, Lothar R. Schad3

1German Cancer Research Center, Heidelberg, Germany; 2Friedrich Schiller - University, Jena, Germany; 3Faculty of Medicine Mannheim, University Heidelberg, Germany

A signal decay model valid in the static dephasing regime is commonly used to map the oxygen extraction fraction (OEF) in the brain. In this work, the model was examined in a phantom study under non-static conditions, i.e. small vessel radius. Our measurements show that water diffusion must be taken into account to obtain proper OEF values for small vessel diameters. Both methods become unstable when more than two fit parameters are used, this can be a severe problem in vivo. Furthermore, using T2 as a fit parameter in the static model seems to give misleading results.

                  1428.     Tissue (Brain) Water Longitudinal Relaxation is Biexponential

Andrew M. Prantner1, G L. Bretthorst, Jeffry J. Neil, Joel R. Garbow, Joseph J H Ackerman

1Washington University in St Louis, St Louis, Missouri, USA

Longitudinal relaxation rates in vivo are typically modeled as a monoexponential function because few TI values are collected. When the number of TI values is increased, multiple R1 components can be resolved in peripheral nerve but not in brain gray matter. High-resolution IR data on in vivo rat brain using either 64 or 128 exponentially spaced TI values indicates that there is a ubiquitous distribution of voxels in rat brain gray matter that are best modeled as a biexponential function because of magnetization transfer.

                  1429.     Fast Quantitative T2* Mapping with Elimination of Macroscopic Susceptibility Artifacts

Yu-Guang Meng1, Hao Lei1

1Wuhan Institute of Physics and Mathematics, Chinese Academy of Science, Wuhan, People's Republic of China

In this work, a novel fast z-shimming method was proposed to acquire quantitative T2* maps in the presence of macroscopic susceptibility artifacts. The method is based on acquisition of two gradient-echo images in the same scan, one at very short echo time without compensation and the other at long echo time but with compensation for in-slice field inhomogeneities. The feasibility of the method was demonstrated in vivo.

                  1430.     Evidence of Multiexponential T2 in Rat Glioblastoma

Richard D. Dortch1, 2, Thomas E. Yankeelov1, Mark D. Does1

1Vanderbilt University, Nashville, Tennessee, USA

Multiexponential T2 (MET2) analysis is capable of decomposing bulk NMR signal into components that represent underlying tissue compartments. The goal of this preliminary study was to determine whether MET2 analysis could be applied in a rat glioblastoma tumor model in vivo. Results showed tumor signal to be biexponential, with a short-T2 component (16 ± 12 ms) representing 6 ± 8 % of the signal and a long-T2 component (75 ± 12 ms) representing the remaining signal fraction. Thus, MET2 holds promise as a non-invasive tool for characterizing tumor microenvironment in vivo.

                  1431.     Multi-Channel Line-Sharing for Rapid T1 Mapping: Application to TAPIR

Nadim Jon Shah1, Irtiza Ali Gilani1, Heiko Neeb1, A M. Oros-Peusquens1

1Institute of Neurosciences and Biophysics (Medicine), Research Centre Jülich, Jülich, Germany

Measurement of the spin-lattice relaxation time constant, T1, can provide important insights into pathological processes in the human brain such as multiple sclerosis or hepatic encephalopathy. Acquisition times, however, tend to be long and therefore reductions through line sharing are desirable. TAPIR, a Look-Locker based multislice, multishot sequence for rapid T1 mapping  is capable in vivo quantification with high spatial resolution by interleaving the slices and time-points. The objective of this work is to accelerate TAPIR using a multi-channel, line-sharing method which acquires sufficient k-space data for high quality T1 mapping. The method is generally applicable to relaxation time mapping.

                  1432.     Iterative Reconstruction for R2 Mapping Based on Radial Fast Spin-Echo MRI

Kai Tobias Block1, Martin Uecker1, Jens Frahm1

1Biomedizinische NMR Forschungs GmbH, Goettingen, Germany

The present work describes a novel reconstruction method for radial fast spin-echo MRI which obtains a spin-density and relaxivity map directly from the measured data without calculating intermediate images. This allows for an efficient T2 quantification from a single radial data set. The method is based on an inverse formulation of the problem and involves a modeling of the received MRI signal. Because a solution is found by a numerical optimization procedure, the approach makes optimal use of all data acquired. Experimental data for the human brain in vivo is presented to demonstrate the feasibility of the method.

                  1433.     A Simple Noise Correction for Rapid T1 Measurements

Carl Ganter1, Rene Botnar2, Marcus Settles1

1Technical University Munich, Munich, Germany; 2King’s College London, London, UK

Rapid T1 measurements like Look-Locker or IR-TrueFISP are very susceptible to low SNR values, especially near the zero-crossing of the magnetization. But even for very low SNR, reliable results can still be obtained, if the measured signal is fitted against its expectation value according to the Rician distribution, using noise a additional fit parameter. This is particularly helpful, when noise is not easily accessible in the experiment, e.g. if parallel imaging is used.

                  1434.     Between Session Reproducibility and Between Subject Variability of Absolute T1

Jan Scholz1, Heidi Johansen-Berg2, Sean Deoni2

1FMRIB Centre, Oxford, UK; 2FMRIB Centre, UK

T1 relaxation times provide quantitative assessment of pathology and have the potential to provide a measure of structural changes due to disease, recovery or learning. We acquired high-resolution whole-brain quantitative T1 maps with the DESPOT1 protocol in multiple subjects on several occasions to access the intra- and inter-session reproducibility of T1 measurements. These values will be useful to determine power and sample size required to detect changes in T1 values over time. In combination with other markers of structural properties these T1-maps might help to elucidate the processes underlying structural changes in the human brain.

                  1435.     A Multiple Species Separation Method Based on T1

Dehe Weng1, 2

11Siemens Mindit Magnetic Resonance Ltd, Shenzhen, People's Republic of China; 2Institute of Biophysics, Chinese Academy of Sciences, Beijing, People's Republic of China

Introduction  New technique for multiple species separation based on T1 was introducedMethod  Description theory of this methodResult  Separation result images with phantomDiscussion  Advantage and disadvantage of new technique

                  1436.     Accelerated T1 Mapping for Brain MRI Perfusion Quantification

Jessy J. Mouannes1, Wanyong Shin2, Maulin Shah1, Timothy J. Carroll1

1Northwestern University, Chicago, USA; 2National Institute of Health, Bethesda, USA

An accelerated method for brain T1 mapping before and after contrast agent injection  for MR perfusion quantification is presented, which has the potential to substitute for the conventional, time-consuming T1 mapping technique that applies least square fitting to compute T1 value for each voxel. By including this new method in our fully automatic reconstruction chain for cerebral blood flow and cerebral blood volume quantification using the Bookend technique, we can facilitate the widespread dissemination of this technique and its clinical use.

 

Image Reconstruction

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  1490.     Rapid Non-Cartesian Parallel Imaging Reconstruction on Commodity Graphics Hardware

Thomas Sangild Sørensen1, David Atkinson1, Redha Boubertakh, 12, Tobias Schaeffter2, Michael Schacht Hansen3

1University College London, London, UK; 2King's College London, London, UK; 3University College London, UK

This presentation describes an implementation of non-Cartesian SENSE and kt-SENSE accelerated on commodity graphics hardware. This inexpensive hardware platform is now fully programmable and very suited for solving reconstruction problems. We show that for both SENSE and kt-SENSE the reconstruction time per frame is now below the acquisition time providing non-Cartesian reconstruction with only minimal delay between acquisition and subsequent display of images. This is demonstrated by four-fold and eight-fold undersampled real-time radial imaging reconstructed in 25 ms to 55 ms per frame.

                  1491.     Interactive Adjustment of Regularization in SENSE and K-T SENSE Using Commodity Graphics Hardware

Michael Schacht Hansen1, David Atkinson1, Thomas Sangild Sorensen1

1University College London, London, UK

This project demonstrates that modern commodity graphics cards (GPUs) can be used to perform fast Cartesian SENSE and k-t SENSE reconstruction. Specifically, the SENSE inversion is accelerated by up to two orders of magnitude and is no longer the time-limiting step. The achieved reconstruction times are now well below the acquisition times thus enabling real-time, interactive SENSE imaging, even with a large number of receive coils. The fast GPU reconstruction is also beneficial for datasets that are not acquired in real-time. We demonstrate it can be used for interactive adjustment of regularization parameters for k-t SENSE in the same way that one would adjust window and level settings. This enables a new way of performing imaging reconstruction, where the user chooses the setting of tuneable reconstruction parameters, in real-time, depending on the context in which the images are interpreted.

                  1492.     Real-Time High-Throughput Scalable MRI Reconstruction Via Cluster Computing

Eric Allen Borisch1, Roger C. Grimm1, Phillip J. Rossman1, Clifton R. Haider1, Stephen J. Riederer1

1Mayo Clinic, Rochester, Minnesota, USA

Real-time 3D MR reconstruction, enabled through parallel imaging techniques such as SENSE and GRAPPA, places significant communication and computational challenges on a reconstruction system. We have designed and implemented a distributed, scalable cluster-based image reconstruction system that has enabled real-time 3D reconstruction and visualization during data acquisition. The hardware and software techniques used will be described, as well as reconstruction performance and benchmarks.

                  1493.     Fast MR Image Reconstruction Using Graphics Processing Units

Justin P. Haldar1, Sam S. Stone1, Haoran Yi1, Stephanie C. Tsao1, Bradley P. Sutton1, Wen-mei W. Hwu1, Zhi-Pei Liang1

1University of Illinois at Urbana-Champaign, Urbana, Illinois, USA

Advanced algorithms for image reconstruction are becoming increasingly common, but their utility is limited by computational requirements.  In this work, we show that significant improvements in reconstruction speed can be achieved by performing data-parallel computations on graphics processing units (GPUs).   Specifically, we leverage the resources of a single NVIDIA GeForce 8800 GTX to achieve computational performance of more than 150 GFLOPS, hundreds of times faster than what is reported on a single modern central processing unit (CPU).

                  1494.     Optimized Post-Processing of 7Tesla Simultaneous Triple Contrast: T1-Weighted, TOF Arteriography,
                                 and BOLD Venography

Peter A. Wassenaar1, Joseph Dunbar1, Donald William Chakeres1, Darlene Meeks1, Michael V. Knopp1, Petra Schmalbrock1

1Ohio State University, Columbus, USA

Inversion Recovery dual turbo gradient echo (IR-dTFE) imaging at ultrahigh field strength can generate images with three types of contrast simultaneously. These are T1 weighting and TOF- arteriography on the first echo and BOLD venography on the second echo. For the MRA information to be useful it is necessary to reconstruct MIP images depicting the vasculature in three dimensions. However, while arteries and veins are well depicted on the original images, standard MIP fails because of increased skull and parenchymal signal. We present here a method for processing 7T IR-dTFE images allowing for MIP visualization of arteries and veins.

                  1495.     Slight Modification of Reconstruction Improves the Isotropy of Non-CPMG

Patrick Le Roux1

1GEHC, Palaiseau, France

The non-CPMG sequence permits to acquire phased object in Spin Echo mode without relying on the Carr-Purcell-Meiboom-Gill constrain. But it still suffers from some magnitude  modulation when the initial phase of the magnetization varies. It is shown that a slight modification of the reconstruction process, projection direction or change of the reference axis,  permits to reduce this anisotropy effect to less than 1%.

                  1496.     Dynamic Imaging Methods Assessed with a 2D MTF Approach

Bruno Madore1

1Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA

As the field of dynamic imaging is expanding and new methods are introduced, reliable methodologies to assess the performance of these methods would be highly desirable. We propose here a 2D Modulation Transfer Function (MTF) approach, whereby the performance of a given method gets tested at every combination of spatial and temporal frequencies. As an example, the performance of two dynamic imaging methods, kt-SENSE and UNFOLD-SENSE, was tested.

                  1497.     SETS: Simultaneous Equations with Taylor Expansions in Undersampled Cartesian Data

Jason Kraig Mendes1, Dennis L. Parker1

1University of Utah, Salt Lake City, USA

Imaging time constraints often prevent the acquisition of a full k-t space for dynamic objects.  In many instances, only part of the k-t space is acquired and the missing information can be approximated using various techniques.  UNFOLD is a method which assumes that more than one spatial point can share the same temporal bandwidth without overlap.  This work presents a method based on the theory of UNFOLD that allows some degree of overlap in the temporal bandwidth.  This can be accomplished with a Taylor series approximation of the signal intensities from each spatial point in the image.

                  1498.     3D Reproducing Kernel Hilbert Spaces for Reconstruction of Heart Rate Modulated Cardio-Respiratory
                                 Magnetic Resonance Imaging

Nicolae Cîndea1, 2, Freddy Odille1, 2, Gilles Bosser3, 4, Jacques Felblinger2, 3, Pierre-André Vuissoz1, 2

1Nancy University, Nancy, France; 2Inserm, Nancy, France; 3Centre Hospitalier Universitaire, Nancy, France; 4Institut Régional de Réadaptation, Nancy, France

Heart MRI reconstructions in free-breathing acquisition is a challenge. Usual techniques assume identical rescaled copies of heart cycle independently of RR length. In this work, a method for cardio-respiratory acquisition and reconstruction in free-breathing taking RR into account is presented. This method uses a Reproducing Kernel Hilbert Space (RKHS) interpolation scheme for retrospective gated reconstruction in 3 dimensions (cardio-respiratory phase and instantaneous heart rate). With this scheme, it is possible to study  the cardio-respiratory interactions and particularly respiratory modulation of heart rate and diastolic filling. Clinical cardiac images were reconstructed at a fixed cardio-respiratory phase for two different RR values.

                  1499.     An Automatic Stopping Criterion for Iterative MRI Reconstructions

Martin Uecker1, Kai Tobias Block1, Jens Frahm1

1Biomedizinische NMR Forschungs GmbH am MPI für biophysikalische Chemie, Goettingen, Germany

Image reconstructions from undersampled data such as in parallel imaging require the inversion of an ill-posed linear (or non-linear) system. In these cases the quality of the reconstruction critically depends on the choice of the regularization which requires a trade-off between substantial noise and still visible undersampling artefacts. Here, we propose an automatic stopping criterion which terminates the iteration as soon as all undersampling artefacts are fully removed. This is accomplished when the energy density of the inferred k-space positions equals the energy density of the directly measured positions. In an image without undersampling artefacts both quantities should be equal.

                  1500.     Variable Spatial Resolution Reconstruction from Data Acquired with Non-Constant Sampling Density in
                                Phase-Encoding Direction

Volker Rasche1, Axel Bornstedt1, Vinzenz Hombach1

1University of Ulm, Ulm, Germany

The variable gridding kernel extent technique is applied for the reconstruction of data acquired on a Cartesian sampling pattern with gradually decreasing dasmpling density in phase encoding (PE) dierection. Examples of carotid artery images show a possible reduction of imaging time of about 70% under the compromise of grdually decreasing spatial resolution along PE direction.

                  1501.     Tradeoff Analysis of Variable Density Spiral K-Space Trajectories Used in MRI

Dimitris Mitsouras1, Onur Afacan2, Dana H. Brooks2, Frank J. Rybicki1

1Harvard Medical School & Brigham And Women's Hospital, Boston, Massachusetts, USA; 2Northeastern University, Boston, Massachusetts, USA

Variable density k-space trajectories, such as spirals, have been recently used in many applications to enhance acquisition speed. In such schemes k-space sampling density is reduced below the Nyquist rate, typically as a function of distance from the k-space center. While their use and diversity is rapidly increasing, a systematic comparison and characterization of their tradeoffs has not been performed to-date. Moreover, various reconstruction methods have been proposed for such trajectories. This work provides such an analysis of different variable density trajectories and different reconstruction methods using well-founded metrics such as SNR, root-mean-square error, and point-spread function analysis.

                  1502.     Fast and Accurate Implementation of Radial K-T FOCUSS for Dynamic MRI Using Implicit Gridding

Jaeheung Yoo1, Jong Chul Ye1

1KAIST, Daejeon, Republic of Korea

For dynamic MR imaging , radial trajectory is often employed since it is more robust to motion artifacts due to the over-sampled k-space center region. Furthermore, scan time can be further reduced using view undersampling. However, this view undersampling often causes visually annoying streaking artifacts. In radial k-t FOCUSS [1], high spatio-temporal cine imaging without streaking artifact were successfully obtained from undersampled radial trajectory using FOCUSS(FOCal Underdetermined System Solver) [2] that exploits the sparsity of fact x-f support of cardiac cine. We further showed that radial k-t BLAST/SENSE is an approximation of our radial k-t FOCUSS that is asymptotically optimal from compressed sensing perspective. However, the radial k-t FOCUSS was computationally expensive due to the iterative application of the projection and backprojection steps. Application of gridding algorithm to reduce the computational complexity was, however, not often successful due to the propagation of gridding artifacts during FOCUSS iteration. The main contribution of this paper is to eliminate the necessity of gridding or backprojection/reprojection steps by showing that the non-regular sampling structure can be easily incorporated as a filtering process during k-t FOCUSS iteration in regular grid. This implicit gridding operation incurs only minimial computational overhead. Experimental results demonstrate that the modified radial k-t FOCUSS significantly improves the radial k-t FOCUSS algorithm both in reconstruction speed as well as image quality.

                  1503.     A Very Fast Reconstruction Algorithm for Non-Cartesian Multi-Coil Dynamic MRI

Uygar Sümbül1, Juan Manuel Santos1, John Mark Pauly1

1Stanford University, Stanford, California , USA

A very fast reconstruction algorithm is presented for non-Cartesian parallel dynamic MRI. The algorithm constrains the images both spatially(via the coil sensitivities) and temporally(via estimating how rapidly individual pixel values change) to achieve alias-free reconstructions. The only major computations are 2 gridding and 2 Fourier operations per each frame. Dynamic whole heart imaging experiments show high temporal resolution of rapidly moving cardiac structures.

                  1504.     Image Enhancement Via Sliding Window Method for Thermal Noise Reduction

Christine S. Law1, Chunlei Liu1, Gary H. Glover1

1Stanford University, Stanford, California , USA

We propose a sliding window self-calibrated parallel imaging method that reduces thermal noise and provides SNR gain over conventional SENSE reconstruction. This method calculates sensitivity profiles dynamically by using a sliding window approach: combining fully sampled data of adjacent frames in an interleaved acquisition, i.e., sensitivity profiles are updated synchronously with image acquisition.  No spatial smoothing is performed so as to retain thermal noise in sensitivity profiles.  This sliding window technique is especially applicable to acquisition of high spatial-resolution images where thermal noise predominates.

 

High Field Spectroscopic Quantitation & Methodology

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                 1590.     LASER  1H-MRS Optimized for Prostate Spectroscopy with Low B1

Ronald Ouwerkerk1

1Johns Hopkins University School of Medicine, Baltimore, Maryland, USA

The fully adiabatic 1H-MRS LASER sequence was modified for use with lower B1s. Refocusing pulses were optimized for minimum threshold and maximum bandwidths. The LASER sequence with Optimized Pulses (LASEROP) was tested in simulation using Bloch equations, which showed a B1 threshold of about 20 μ]T for 4 kHz BW. On phantoms with body coil excitation and with body coil loads the sequence produced excellent spectra of a citrate-containing phantom at TE 39 ms requiring only 21 μ T peak B1 field. This is particularly useful for 1H-MRS of the prostate where the LASER sequence can provide spectra that are much easier to quantify.

                  1591.     Semi-LASER 1H-MR Spectroscopic Imaging of the Human Brain at 7T

Tom WJ Scheenen1, Dennis WJ Klomp1, Pierre-Francois van de Moortele2, Gregor Adriany2, Arend Heerschap1

1Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands; 2University of Minnesota, Minneapolis, Minnesota, USA

The semi-LASER pulse sequence is a combination of conventional non-adiabatic slice-selective excitation and double slice-selective refocusing by two pairs of adiabatic full passage pulses. Combined with an efficient 16 channel head coil the sequence can produce a 3D spin echo localized volume of interest at an echo time of 30 ms. With a small chemical shift displacement error and the relative insensitivity for B1 inhomogeneities, the semi-LASER technique is able to provide useful MR spectra over a large part of the brain at 7T without additional lipid or outer volume suppression.

                  1592.     Proton Spectroscopy of Human Brain at 3T and 7T: Signal-To-Noise Ratio, Spectral Linewidth and
                                 Relaxation Times

Yan Li1, 2, Duan Xu1, Albert P. Chen1, Daniel B. Vigneron1, Sarah J. Nelson1

1University of California, San Francisco, California , USA

The purpose of this study was to estimate the relaxation times of Cho, Cr and NAA at both 3T and 7T, to evaluate the effects of relaxation times in the long echo time acquisition, to examine the differences in SNR between 3T and 7T and to investigate how the acquisition parameters influence the quality of the spectra. Statistical significance was found for both T1 and T2 values of metabolites between 3T and 7T for all metabolites except for the Cho T1 value. After corrections for relaxation parameters, the SNR ratios between 7T and 3T were on average 1.53. 

                  1593.     High Spatial Resolution Short TE Proton-Echo-Planar-Spectroscopic-Imaging (PEPSI) in Human
                                 Brain at 7 Tesla Using B1-Compensation and Adiabatic Refocusing

Tom WJ Scheenen1, Pierre-Francois van de Moortele2, Gregor Adriany2, Andre van der Kouwe3, 4, Ricardo Otazo5, Stefan Posse5

1Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands; 2University of Minnesota, Minneapolis, Minnesota, USA; 3Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, USA; 4Massachusetts General Hospital, Boston, Massachusetts, USA; 5University of New Mexico, Albuquerque, New Mexico, USA

Non-uniform spatial sensitivity, increased chemical shift displacement errors, lipid contamination due to B1-inhomogeneity, and increased RF power deposition are major challenges for metabolite imaging at ultra-high field (7T). In this study at 7T we combine Proton-Echo-Planar-Spectroscopic-Imaging with paired adiabatic refocusing pulses and B1-compensated outer volume suppression (OVS) to enable short TE (20 ms) metabolite mapping. We demonstrate the feasibility of high spatial resolution (0.25 cc voxel size) metabolite mapping in central and peripheral regions of the human brain in a clinically feasible measurement time using a 16-channel line array headcoil. 

                  1594.     1H NMR T1 Relaxation Times of the Neurochemical Profiles in Rat Brain at 14.1T

Cristina Cudalbu1, Vladimir Mlynárik, Lijing Xin, Rolf Gruetter, 2

1 Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland; 2Departments of Radiology, Universities of Lausanne and Geneva, Switzerland

The aim of the present study was to measure in vivo T1 relaxation times of the neurochemical profiles at 14.1T in rat brain. T1 measurements were accomplished using a progressive saturation technique, which was validated with an adiabatic inversion recovery. The T1 measured at 14.1 T is similar (~10%) to those measured at 9.4 and 11.7T suggesting that for metabolites, T1 increases are of minimal consequence beyond 9.4 Tesla.

                  1595.     Selective Measurement of Brain Glutamate and Glutamine in Vivo by Spectrally-Selective Refocusing at 7T

Changho Choi1, Chenguang Zhao1, Ivan Dimitrov1, 2, Ana Stan1, Carol Tamminga1

1University of Texas Southwestern Medical Center, Dallas, USA; 2Philips Medical Systems, Cleveland, Ohio, USA

Spectrally-selective refocusing has been applied to separate the signals between glutamate (Glu) and glutamine (Gln) in human brain selectively at 7.0 T. The C4-proton resonances of Glu and Gln, which differ by ~0.1 ppm » 30 Hz), was selectively refocused using a 50-ms long Gaussian 180° pulse implemented within PRESS. Ignoring T1 and T2 effects, an optimal echo time of 137 ms gave Glu and Gln multiplets at 2.35 and 2.45 ppm with peak amplitude 67% and 53% with respect to 90°-acquisition respectively. Preliminary in vivo results from the human brain are presented. 

                  1596.     Analysis of 1H Metabolite Ratios Using Image Segmentation at 7T in Adult Patients with X-Linked
                                Adrenoleukodystrophy

Trina Kok1, Eva-Maria Ratai2, 3, Florian Eichler, 34, Elfar Adalsteinsson1

1Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, USA; 2A.A. Martinos Center for Biomedical Imaging, Cambridge, Massachusetts, USA; 3Harvard Medical School, Boston, Massachusetts, USA; 4A.A. Martinos Center for Biomedical Imaging,, Cambridge, Massachusetts, USA

The combination of segmented structural data with low-SNR spectroscopy has been used to provide brain metabolite estimates in separate tissue compartments [1-3]. To correct for comparison across subjects under different scanning conditions, expressing metabolite signals as ratios to the sum of the metabolite signals from Cr and PCR (Cr') is a common technique. We extend compartmental analysis of absolute metabolite measures to ratio measures, and demonstrate its use in a study of NAA+NAAG (NAA') changes in X-linked adrenoleukodystrophy at 7T

                  1597.     Composition of Adipose Tissue and Marrow Fat by 1H MR Spectroscopy at 7 Tesla

Jimin Ren1, 2, Ivan Dimitrov1, 3, A. Dean Sherry1, Craig Malloy1, 4

1University of Texas Southwestern Medical Center, Dallas, USA; 2Advanced Imaging Research Center, Dallas, USA; 3Philips Medical Systems, Dallas, USA; 4VA North Texas Health Care System, Dallas, USA

1H MR spectra were obtained from subcutaneous adipose tissue and bone marrow in the tibia in 10 healthy subjects at 7T.  The ultra-high field spectroscopy offers a simple method to obtain detailed information about fatty acid composition, due to well-resolved proton resonances for all major structural fragments including –CH3, -(CH2)n-, -CH2-COO, -CH2-CH2-COO, -CH=CH-, -CH=CH-CH2-CH=CH, -CH2-CH2-CH=CH-,  and in some instances from the methine and methylene protons of glycerol backbone. The composition of marrow and adipose fat were similar, ~24-26% polyunsaturated, 46-49% monounsaturated and 28-29% saturated. The estimated fraction of 16-carbon and 18-carbon fatty acids was about 32% and 68%, respectively.

                  1598.     Proton Spectroscopic Imaging of the Human Prostate in Vivo at 7T

Dennis Klomp1, Andreas Bitz2, Arend Heerschap1, Tom Scheenen1

1Radboud University Nijmegen, Medical Center, Nijmegen, Netherlands; 2Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany

To meet the demand for a better sensitivity in 1H MRSI of the prostate the magnetic field strength of 7T can be employed. We introduce the endorectal RF coil as a tranceiver, validate its safety for in vivo use and present a new pulse sequence optimzed for 3D MRSI of the human prostate at 7T. Safe use of the coil was validated with SAR calculations, MR thermometry and in vivo temperature monitoring. The pulse sequence was designed and validated with quantum mechanical simulations, phantom and in vivo measurements.

                  1599.     Adiabatic T and T Relaxation Measurements of J-Coupled Spins. Results from Phantoms and from
                                the Human Brain at 4T

Silvia Mangia1, Michael Garwood1, Dennis Sorce1, Kamil Ugurbil1, 2, Shalom Michaeli1

1University of Minnesota, Minneapolis, Minnesota, USA; 23.  Max Planck Institute for Biological Cybernetics, Tubingen, Germany

The phase modulation introduced by J-evolution complicates the analysis of spectra, and impairs the possibility of estimating relaxation rates of J-coupled spins. The phantom and in vivo results presented in this work demonstrate that rotating frame relaxation measurements (T and T) performed with specific configurations of adiabatic full passage pulses are not affected by J-evolutions. This notably simplifies the estimation of relaxation rates in the rotating frame also for resonances other than singlets. Since the analysis of the relaxation rates measured in the rotating frame can provide quantitative information on the spin dynamics, our results imply that dynamics of several compounds relevant for brain function and metabolism (as for instance glutamate) can be probed by adiabatic T and T relaxation measurements.

                  1600.     Reproducibility of Cerebral Metabolite 1H T2 Relaxation Measurements at 3T  [Not Available]

Audrey Jennifer Chang1, Sergey Cheshkov1, Subhendra Sarkar1, Richard Briggs1

1UT Southwestern Medical Center, Dallas, Texas, USA

MR spectroscopy has become a valuable tool in the investigation of the pathologies underlying many neurodegenerative disorders.  The goal of this study is to investigate the reproducibility of metabolite T2 relaxation time measurements in normal subjects at 3T, and to develop a standard protocol for acquisition of T2 relaxation measurements in neurodegenerative disease patients within a clinically feasible scan time (1 hr).  In addition to influencing the ability to detect significant changes in cerebral metabolite concentrations, information about variation in time of T2 relaxation measurements might provide insight into molecular mechanisms of disease progression. 

                  1601.     In Vivo J-Difference Lactate Editing at 3.0 Tesla

Mari A. Smith1, Jason A. Koutcher1, Kristen L. Zakian1

1Memorial Sloan-Kettering Cancer Center, New York, USA

The goal of this study was to implement in vivo detection of lactate by J-difference editing 1H MRS on a 3 Tesla human scanner for potential applications in patients. The current study extends the previous work cited in the literature regarding BASING editing for lactate detection by testing the sequence in the presence of high lipid concentrations in vivo at 3 T. The results demonstrate the ability of the BASING J-difference technique to detect lactate in the presence of strong lipid signals and indicate successful lactate editing in the presence of lipid at 3 T.

                  1602.     Turbo Spin Echo Based Spatially Resolved Correlated Spectroscopic Imaging

Gaurav Verma1, Saadallah Ramadan2, 3, Scott Lipnick1, Nagarajan Rajakumar1, M. A. Thomas1

1UCLA, Los Angeles, California , USA; 2Brigham & Women's Hospital, Boston, Massachusetts, USA; 3Harvard Medical School, Boston, Massachusetts, USA

The purpose of this study is to develop a turbo spin echo (TSE) based sequence for recording multi-voxel based 2D COSY MR Spectra. Through incorporating an echo train in each TR rather than a single acquisition, which has been routinely used in conventional MR Spectroscopic Imaging (MRSI), the data acquisition was accelerated by a factor of 4 or more, thus reducing the total duration required for recording 4 dimensional (4D) MRSI (2D Spatial, 2D Spectral) to times reasonable for adding this sequence to any clinical MRSI protocol.

                  1603.     A Pilot Comparison of 2D and 1D MR Spectroscopic Quantitation of Metabolites in Healthy Human
                                 Brain at 3T

Enrique Frias-Martinez1, Nagarajan Rajakumar1, S. Ramadan1, S. Banakar1, X. Liu1, A. Singhal1, Michael Albert Thomas1

1UCLA, Los Angeles, California , USA

Using a 3T MRI scanner, spatially resolved two-dimensional (2D) MR spectra including L-COSY and JPRESS, and one-dimensional (1D) PRESS spectra were recorded in the occipital white/gray matter regions of healthy human volunteers. ProFit algorithm was used to quantify the 2D MRS raw data and LC-Model for the 1D signal. Eight healthy volunteers and a white matter phantom have been investigated so far. Preliminary results indicate that COSY-ProFit provides better specificity that JPRESS-ProFit, and both of them provide better specificity and a higher number of detected metabolites than 1D PRESS processed using LC-Model. 

                  1604.     Tissue-Dependent Analysis of Metabolic Alterations in the Brain by MR Spectroscopic Imaging

Andrew A. Maudsley1, Colin Studholme2, Varanavasi Govindaraju1

1University of Miami, Miami, Florida, USA; 2University of California San Francisco, San Francisco, California , USA

A method for analysis of single-subject metabolite images is presented that uses knowledge of the local tissue distributions and of the tissue-specific metabolite values generated from a group of comparison subjects. By incorporating spatial normalization procedures that convert all metabolite image results to a standardized space, this procedure enables voxel-based analyses without the requirement for accurate spatial alignment on the sulcal level. 

                  1605.     Assessment of Normative Metabolite Variations in Fronto-Cerebellar Voxels Using 1H MRS

Kevin Wayne Waddell1, Parham Zanjanipour2, Subechhya Pradham1, James M. Joers1, Edward Brian Welch3, Peter R. Martin1, Malcolm J. Avison1, John C. Gore1

1Vanderbilt University, Nashville, USA; 2University of Kentucky, Lexington, USA; 3Vanderbilt University, Nashville, Tennessee, USA

The relationships of N-acetyl aspartate (NAA) and choline-containing compounds in the anterior cingulate and cerebellar vermis of chronic alcoholics have previously been studied using proton spectroscopy. Advances in clinically available high-field scanners have made it possible to measure levels of the major inhibitory neurotransmitter, gamma-aminobutyric acid (GABA), in these areas. We used these methods to establish normative fronto-cerebellar concentrations of metabolites using J-difference spectroscopy. We found that ratios of GABA* with respect to creatine are 140% higher on average than their cerebellar-vermian counterparts. Corresponding ratios of glutamate and NAA were also elevated in the anterior cingulate.

                   1606.     The Roles of PCr in Brain Activity

Mary C. Stephenson1, Kay E. Head1, Andrew M. Peters1, Dorothee P. Auer, Peter G. Morris1

1University of Nottingham, Nottingham, UK

Activation in the brain increases energy use but, due to the haemodynamic response there is a delay of a few seconds in the supply of additional glucose and oxygen.  This study uses 31P spectroscopy to explore the possible role of PCr in meeting energy demand during this first few seconds of activation.  Three seconds after the onset of intense visual stimulation we measured small increases in PCr, decreases in Pi and pH.  These are consistent with the energy shuttle hypothesis but not a buffering role for PCr.

                  1607.     Blipped Phase-Encoding in MR Spectroscopic Imaging Revisited: Comparison to SENSE-MRSI

Peng Qu1, Joseph Gillen1, Peter B. Barker1, 2

1Johns Hopkins University, Baltimore, Maryland, USA; 2Kennedy Krieger Institute, Baltimore, Maryland, USA

Blipped phase-encoding (BPE) has previously been used to accelerate echo-planar spectroscopic imaging sequences. However, it apparently has not been applied to conventional magnetic resonance spectroscopic imaging (MRSI). This abstract describes the implementation of BPE-MRSI on 1.5 and 3.0T systems, and compares the results to those from sensitivity-encoded MRSI.

                  1608.     Volumetric Spiral Chemical Shift Imaging with 32-Channel Receive Coil at 3T with Online Gridding
                                Reconstruction

Borjan Aleksandar Gagoski1, Michael Hamm2, Jonathan Polimeni3, 4, Gunnar Krueger5, Eva-Maria Ratai3, 4, Graham Wiggins3, 4, Uwe Boettcher6, Joonsung Lee1, Florian Eichler3, 4, Stefan Roell7, Elfar Adalsteinsson1, 8

1Massachusetts Institute of Technology, Cambridge, Massachusetts, USA; 2Siemens Medical Solutions, Charlestown, Massachusetts, USA; 3A. A. Martinos Center for Biomedic Imaging, Charlestown, Massachusetts, USA; 4Harvard Medical School, Boston, Massachusetts, USA; 5Siemens Medical Solutions, Lausanne, Switzerland; 6Siemens Medical Solutions, Erlangen, Germany; 7Siemens Medical Solutions, Malvern, Pennsylvania, USA; 8Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, USA

Coil arrays with large number of receive elements are well suited for the time-efficient CSI acquisitions, as they provide important SNR gain for metabolite detection. In this work we make use of the encoding efficiency of the spiral CSI to quickly encode 3D volumetric brain acquisitions with small voxel sizes. We use a custom-built 32-channel coil array to maximize SNR and fast online gridding reconstruction. We present in-vivo results demonstrating that combining the spiral CSI with large receive coil arrays yields large-volume, high-resolution spectroscopic imaging data.

                  1609.     Proton-Echo-Planar-Spectroscopic-Imaging (PEPSI) Acquired Using Radial Trajectory (RPEPSI)

Shang-yueh Tsai1, Yi-Ru Lin2, Teng-Yi Huang3, Stefan Posse4, 5, Fa-Hsuan Lin6, 7

1Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan; 2Dept. of Electronic Engineering, National Taiwan University of Science and Technology, Taiwan; 3Dept. of Electrical Engineering, National Taiwan University of Science and Technology, Taiwan; 4Dept. of Psychiatry, University of New Mexico, Albuquerque, New Mexico, USA; 5Dept. of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico, USA; 6Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts, USA; 7MGH-HMS-MIT Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, USA

Proton Echo Planar Spectroscopic Imaging (PEPSI) has been developed to reduce the scan time of 2-dimensional MRSI to the order of several minutes. However the spectral quality may still be influenced by motion. Radial acquisition is known to be less sensitive to motion artifacts compared with Cartesian sampling scheme. Here a radial PEPSI (rPEPSI) sequence is implemented and compared with regular PEPSI. Spectra and metabolite maps quantified with LCModel from rPEPSI and PEPSI are comparable. The concentrations and fitting errors are at similar level. In this preliminary report, we demonstrate the feasibility to combine radial acquisition and PEPSI technique.

                  1610.     Sensitivity Improvements in Peak Detection of Glutamate, GABA and Glutamine in the Human Brain
                                 Using ISIS
                               CT-PRESS at 4.7 T

Hidehiro Watanabe1, Nobuhiro Takaya1, Fumiyuki Mitsumori1

1National Institute for Environmental Studies, Tsukuba, Japan

A ISIS CT-PRESS sequence was implemented on a 4.7-T whole-body spectrometer for peak detection of glutamate, GABA and glutamine in the human brain with higher sensitivity. Three diagonal peaks of GABA C2H (2.28 ppm), Glu C4H (2.35 ppm) and Gln C4H (2.44 ppm) were resolved on CT-PRESS spectra of a phantom containing a brain mixture. Signal to noise ratio of Glu C4H on a CT-PRESS spectrum was 2.24 times higher than that obtained by localized CT-COSY. In volunteer studies, these three peaks were resolved on CT-PRESS spectra of parieto-occipital regions with sensitivity improvement by a factor of 1.7.

                  1611.     Optimized CT-PRESS for Localized Proton NMR Spectroscopy of the Human Brain at 3 Tesla

Wolfgang Dreher1, 2, Dmitry Ebel1, 2, Dieter Leibfritz1, 2

1University of Bremen, Bremen, Germany; 2Center for Advanced Imaging (CAI), Bremen, Germany

Different ways to optimize CT-PRESS measurements and maximize the SNR on a 3 T human head scanner are examined. Short tc values corresponding to the mean echo time are realized by using a short TE PRESS module and an additional rectangular 180 . Strong spoiler gradients make phase cycling obsolete and enable weighted averaging in t1. A local RF transmitter adjustment accounts for spatial B1 inhomogeneities and avoids severe signal losses by deviation from the nominal flip angles. Truncation artifacts can be reduced below the noise level for in vivo measurements by using the S-TRAF function for apodization in t1.

                  1612.     The Reliability of Vitamin C (Asc) Detection in Human Brain Using Standard PRESS on a Clinical
                                 3T MR-Scanner
 [Not Available]

Yi-Yu Shih1, 2, Dominik von Elverfeldt2, Martin Buechert2, Hsiao-Wen Chung1, Juergen Hennig2

1National Taiwan University, Taipei, Taiwan; 2University Hospital Freiburg, Freiburg, Germany

The Asc concentration was successfully detected in 71 of 76 in vivo human brain spectra using PRESS sequence on 3T MR-scanner in our study. To further evaluate the reliability in quantification, three of the spectra with different line-widths were chosen to add artificial Asc spectrum (virtual titration) with different concentrations and SNR levels, followed by analysis via LCModel. The results show the good linearity between added and estimated concentrations of Asc. Other neighboring metabolites (mI and Glx) are only slightly affected (within 10% concentration change) if the line-width was less than 0.043 ppm. Therefore, it is feasible to detect Asc using standard clinical MRS acquisition in combination with LCModel.

                  1613.     Signal Normalization for MR Spectroscopic Imaging Using an Interleaved Water-Reference

Andrew A. Maudsley1, Claudia Domenig1

1University of Miami, Miami, Florida, USA

A signal normalization method for MRSI in the brain is described that uses a tissue water MRSI, obtained using an interleaved measurement, as an internal reference. When combined with spatial registration functions, this procedure enables voxel-based comparisons between repeated studies in the same subject as well as comparisons between subjects. Results for analysis of individual voxel results for intra-subject and inter-subject comparisons are presented, as well as for tissue regression analyses over different brain volumes.

                   1614.     Applying Optimized Variable-Rate Excitation for Outer Volume Suppression in Fast 3D Proton
                                  Spectroscopic Imaging of the Human Brain at 3 Tesla

Dmitry Ebel1, 2, Christian Schuster1, 2, Wolfgang Dreher1, 2, Dieter Leibfritz1, 2

1University of Bremen, Bremen, Germany; 2Center for Advanced Imaging (CAI), Bremen, Germany

Spectroscopic Missing-Pulse SSFP (spMP-SSFP) is a powerful method for fast 3D spectroscopic imaging. However, further improvements are hampered by specific absorption rate (SAR) and timing limitations. In this study, optimized RF and gradient waveforms were applied within spMP-SSFP to improve saturation of extracranial lipid signals. The number of applicable OVS slices was increased when applied on the human brain at 3 Tesla using VERSE-like 90  pulses, calculated by genetic algorithms, with reduced SAR and improved off-resonance behavior. This approach enables better defined regions of interest and will allow to implement spMP-SSFP at higher magnetic fields.

                  1615.     Voxel Based Analysis and Reconstruction of Spectroscopic Imaging Data

Jullie Pan1, Xenophon Papadametris1, Susan Spencer, Dennis Spencer1, Hoby Hetherington1

1Yale University, New Haven, Connecticut, USA

We have developed and implemented methods to identify and reconstruct spectroscopic imaging pixels using either a common anatomical atlas (MNI standard brain) and other imaging modalities (e.g. PET,CT and SPECT) to define the target locations. Co-registration driven selection and registration provides for precise positioning of the target voxels and the elimination of user bias in voxel selection. We have applied these methods to investigate: 1) the extent of asymmetric subcortical metabolic abnormalities in patients with temporal lobe epilepsy and 2) the relationship between regions with abnormal intracranial EEG (electrodes identified by CT) and decreased NAA in patients with neocortical epilepsy.

                  1616.     Resolution Enhancement of Brain Glutamate at PRESS {TE1, TE2} = {35, 75} Ms at 3T

Changho Choi1, Nicholas J. Coupland2, Peter Seres2, Chenguang Zhao1, Sanjay Kalra2, Philip G. Tibbo2

1University of Texas Southwestern Medical Center, Dallas, USA; 2University of Alberta, Edmonton, Canada

PRESS echo time dependence of brain glutamate (Glu) selectivity was investigated, with density-matrix simulation, for TE1 and TE2 between 30 and 80 ms, incorporating the neighboring resonances of glutamine, N-acetylaspartate and glutathione. The numerical calculation indicated that Glu signal intensity and resolution are both maximized at {TE1, TE2} = {35, 75} ms, its peak amplitude being 73% with respect to 90°-acquisition. An in vivo brain spectrum from these subecho times is presented, in comparison with a spectrum from the previously-proposed echo time {40, 40} ms.

                  1617.     Lactate Edited 3D MR Spectroscopic Imaging of Gliomas at 3T Using Ellipsoidal SENSE with BASING
                                 Pulses

Esin Ozturk-Isik1, Wei Bian1, Ilwoo Park1, 2, Albert P. Chen1, Jason C. Crane1, Daniel B. Vigneron1, 2, Susan M. Chang1, Sarah J. Nelson1, 2

1University of California at San Francisco, San Francisco, California , USA; 2University of California at San Francisco and Berkeley, San Francisco, California , USA

Lactate is an important metabolite that has been detected in high-grade brain tumors, ischemia and stroke cases. Lactate detection requires a special editing scheme like the J-difference technique using dual BASING pulses due to coresonant lipid peaks. The J-difference based lactate detection requires two cycles of spectral data acquisition which results in doubled scan time. In this study, we propose to use a fast data acquisition method, the ellipsoidal SENSE technique, with BASING pulses to acquire 3D lactate edited MRSI of brain tumor patients with the clinically feasible scan time of 9 min at 3T.

 

Molecular Imaging Agents:  Applications & Detection

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  1645.     Longer in Vivo Retention and Accumulation Improves Detection of PARACEST MRI Contrast Agents

M. Meser Ali1, M. D. Pagel1

1Case Western Reserve University, Cleveland, Ohio, USA

PARACEST MRI contrast agents suffer from poor temporal resolution and limited detection sensitivity.  Agents with longer in vivo retention times may compensate for poor temporal resolution, and agents that accumulate at high concentrations within in vivo tissues may compensate for limited sensitivity.  The PARACEST agent EuDOTA-OBnS2-Gly2-COOH has both of these advantages relative to EuDOTAMGly, due to the addition of two o-benzyl moieties.  This was demonstrated by the detection of the PARACEST effect of EuDOTA-OBnS2-Gly2-COOH in the in the inferior vena cava, kidney, and liver of a normal mouse.

                  1646.     Heteronuclear Relaxivity of Commercial Gadolinium Contrast Agents

Cristina Gabellieri1, Geoffrey S. Payne1, Martin O. Leach1, Thomas R. Eykyn1

1The Institute of Cancer Research, Sutton, UK

Development of hyperpolarisation techniques have led to increasing interest in non-proton MR for metabolic and molecular imaging. Potential biomarkers with nuclei with long relaxation times are needed to effectively use the high non-equilibrium polarization attained. Here we report relaxivities of two Gd-based contrast agents on 13C in glycine and 15N in choline in aqueous solutions. We also confirm that extracellular contrast agents exert little influence on the relaxation properties of intracellular metabolites by looking at cell suspension by 31P NMR of . This may be important in the future use of hyperpolarized tracers to relax the extracellular parent signal and better observe the intracellular daughter compounds. 

                  1647.     Improved Molecular Imaging of Sparse Neovascular Biomarkers with a Novel Lipophilic Gd-DOTA Chelate
                                on Targeted Nanoparticles

Patrick M. Winter1, Shelton D. Caruthers1, Anne H. Schmieder1, Todd A. Williams1, Dennis Riley, William McGhee, Samuel A. Wickline1, Gregory M. Lanza1

1Washington University, St. Louis, Missouri, USA

The purpose of this study was to compare the relaxivity and in vivo signal enhancement of targeted nanoparticles formulated with two different paramagnetic chelates, Gd-DTPA-BOA and Gd-DOTA-Amide-PE. Nanoparticles were targeted to the α  ν β 3-integrin for molecular imaging of angiogenesis induced by tumor growth. The Gd-DOTA-Amide-PE nanoparticles had 50% higher relaxivity and produced 74% higher enhancement in a rabbit tumor model. These results suggest that paramagnetic chelates with improved relaxivity may facilitate increased sensitivity with molecular imaging agents.

                  1648.     In Vivo Imaging of  α vβ 3 - Targeted Micellar Nanoparticles in an NSCLC Tumor Xenograft Model by
                                 Off-Resonance Saturation Method
 [Not Available]

Chase W. Kessinger1, Chalermchai Khemtong1, Jimin Ren1, Erik A. Bey1, David A. Boothman1, A. Dean Sherry1, Jinming Gao1

1University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA

Here we describe the use of off-resonance saturation (ORS) method to image α v β 3 - targeted superparamagnetic polymeric micelles (SPPM) for the molecular imaging of cancer.  The ORS contrast is achieved by water signal attenuation with an RF pulse set at an off-resonance position to bulk water.  The ORS method was demonstrated in a human NSCLC tumor xenograft model in nude mice in vivo.  The ORS contrast can be turned “on” and “off”, to produce an accurate contrast image of superparamagnetic nanoparticles targeting to tumor neovasculature.

                  1649.     Intracellular Uptake of Targeted Paramagnetic Contrast Agent Leads to Quenching of T1 Contrast

Maarten B. Kok1, Sjoerd Hak1, Willem J.M Mulder2, Daisy van der Schaft1, Gustav J. Strijkers1, Klaas Nicolay1

1Eindhoven University of Technology, Eindhoven, Netherlands; 2Mount Sinai School of Medicine, New York, USA

This study shows that the effective relaxation enhancement introduced by an internalized paramagnetic contrast agent depends crucially on its intracellular localization. The effective T1 relaxivity of internalized áíâ3-targeted liposomes was much lower than that of non-targeted liposomes. This finding has important implications for the interpretation of target specific MRI in vivo, as significant local uptake of contrast agent by target tissue might go undetected.

                  1650.     Novel Method to Characterize Paramagnetic Contrast Agents Association to 2-Dimensional Surfaces

H.M.H.F. Sanders1, H.P. Huinink1, S.J.F. Erich1, O.C.G. Adan1, M. Merkx1, G. J. Strijkers1, K. Nicolay1

1Eindhoven University of Technology, Eindhoven, Netherlands

Receptor mapping of cells lining blood vessels is a major application of molecular MR imaging using targeted contrast agents, for example for atherosclerosis or angiogenesis characterization. Here we show that very high-resolution MRI depth profiling by using a saturation recovery pulse sequence, combined with mathematical modelling, is capable of quantifying the surface water longitudinal relaxation rate induced by a surface-bound contrast agent. This technique is helpful in studying the behavior of targeted contrast agents and will yield valuable insights for the optimization of the MRI-based detection of target-associated contrast agents.

                  1651.     Imaging Targeted Delivery of Liposomes to Tumor Vasculature

Maria Mikhaylova1, Amin Hajitou2, Yoshinori Kato1, Saraswati Sukumar, Dmitri Artemov1, Marie-France Penet1, Wadih Arap2, Renata Pasqualini2, Zaver M. Bhujwalla1

1JHU ICMIC Program, The Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA; 2The University of Texas, MD Anderson Cancer Center, Houston, Texas, USA

We recently identified a novel peptide that binds specifically to breast cancer vasculature.  Here we have examined the potential of this peptide for targeting multifunctional liposomes to tumor vasculature in an MDA-MB-231 human breast cancer model.  In vivo magnetic resonance  imaging revealed specific accumulation of targeted liposomes in tumor vasculature starting at 3h following intravenous injection compared to liposomes with a control peptide.  This finding was supported by optical imaging and immunofluorescent localization.  These data suggest that the newly identified peptide may provide a means to deliver therapeutic and analytical cargo to breast cancers under image-guidance.

                  1652.     Targeted Herceptin-Dextran Nanoparticles for Noninvasive Imaging of Her2/neu Receptor by MRI

Yun-Ming Wang1, Ting-Jung Chen1, Chiao-Yun Chen2, Gin-Chung Liu2

1Kaohsiung Medical University, Kaohsiung, Taiwan; 2Kaohsiung Medical University Hospital, Kaohsiung, Taiwan

The fabrication and characterization of dextran-coated magnetic nanoparticles CLIO-Herceptin as nanoprobes for MR imaging to target specific receptors were reported. From the results, we found that the CLIO-Herceptin had well-dispersed in different pH value solutions, low protein absorption from medium, no hysteresis, high saturation magnetization and low cytotoxicity of different cells. Moreover, CLIO-Herceptin had ability to target the SKBR-3, BT-474, MDA-MB-231 and MCF-7 cells proved by in vitro and in vivo MR imaging studies.

                  1653.     Molecular MRI of the Estrogen Receptor in Human Breast Cancer Cells

Adi Pais1, Chidambaram Gunanathan1, David Milstein1, Hadassa Degani1

1Weizmann Institute of Science, Rehovot, Israel

The estrogen receptor (ER) serves as an important prognostic factor and a marker for predicting response to hormonal therapy. We present two novel contrast agents targeted to ER, composed of a gadolinuimpyridiniumtetraacetate conjugated to estradiol (EPTA-Gd), or to tamoxifen (TPTA-Gd) both with a micromolar binding affinity to ER. These agents exhibited agonistic effect on cell proliferation, disparity in inducing ER degradation and high relaxivities in solution. Concentration dependent studies of T1 and T2 relaxation in viable ER+ cells and in the same cells with null ER indicated a specific binding to ER which reflected the level of this receptor.

                 1654.     Molecular Imaging of Benfluorex Treatment in Diabetic Rats with α vβ 3-Integrin Targeted Nanoparticles

Kejia Cai1, Todd A. Williams1, Shelton D. Caruthers1, 2, Gregory M. Lanza1, Samuel A. Wickline1, Patrick M. Winter1

1Washington University, Saint Louis, Missouri, USA; 2Philips Medical Systems, Andover, Massachusetts, USA

The metabolic syndrome is highly associated with cardiovascular disease. JCR:LA-cp diabetic rats were treated with benflurorex for 15 weeks to study the effects on cardiovascular disease. ávâ3-integrin targeted gadolinium nanoparticles were used for molecular imaging of angiogenesis, a hallmark of atherosclerosis. Benfluorex treatment decreased MR signal enhancement by about 60%, indicating suppression of angiogenesis, and possibly inhibition of atherosclerosis. These results suggest that molecular imaging with targeted nanoparticles can detect cardiovascular disease associated with metabolic syndrome and monitor the treatment response.

                  1655.     Evaluation of Sensitivity Increase by T1 and T2 Contrast Agents in 19F MRI of PF15C

Thomas Christian Basse-Luesebrink1, Thomas Kampf2, Christian Herbert Ziener2, Gert Klug2, Wolfgang Rudolf Bauer2, Peter Michael Jakob2, Daniel Haddad1

1Research Center Magnetic Resonance Bavaria, Wuerzburg, Germany; 2University of Wuerzburg, Wuerzburg, Germany

In this study the influence of T1 and T2 contrast agents in 19F MRI on SNR per measurement time is investigated.  Therfore Turbo Spin Echo (RARE) and Fast Gradient Echo (FLASH) sequences are applied to different cases. As a result this study suggests that the usage of T1 contrast agents is not generally preferable.

                  1656.     On the Optimal Field Strength for Detection of Targeted Gd-Based Contrast Agents in Molecular
                                MR Imaging

Olivier Girard1, Philippe Robert2, Luc Darrasse1

1Univ Paris-Sud, CNRS, Orsay, France; 2Guerbet Recherche, Roissy Charles-De-Gaulle, France

Molecular MR Imaging using targeted Contrast Agents (tCA) is a promising tool for early diagnosis purpose. For macromolecular Gd-based CA (e.g. a tCA bound to its target) the T1-relaxivity tends to decrease rapidly above 20-30 MHz raising the question of their efficiency at high field. We investigate theoretically and experimentally the Contrast-to-Noise Ratio (CNR) obtained with a paramagnetic tCA as a function of the field strength, accounting for NMRD profiles derived from experimental data. Results indicate that  Molecular MR Imaging with Gd-based tCA do not benefit from high field strength and should be performed  around 1-1.5 T to optimise the CNR and differentiate bound and free pools of tCA.

                 1657.     Early Stage Investigations of USPIO-Induced Signal Changes After Focal Cerebral Ischemia in Mice

Virginie Desestret1, Jean-Christophe Brisset1, Emilie Devillard1, Samir Moucharrafie1, Serge Nataf2, J. Honnorat2, Norbert Nighoghossian1, Yves Berthezene1, Marlène Wiart1

1Creatis-LRMN (UMR CNRS 5220, Inserm U630), Bron, France; 2Inserm U842, Bron, France

The interpretation of USPIO-induced MR signal changes at the early stages of focal cerebral ischemia remains controversial. Cerebral infarctions were induced in 40 mice using permanent middle cerebral artery occlusion (pMCAO) by electrocoagulation. Ferumoxtran-10 USPIO (Guerbet, France) were injected i.v. 5h post-injury. On gradient echo T1- weighted imaging, four areas of signal changes after USPIO injection were observed at 6 and 24h post ischemia. On histology, iron staining was mostly associated to the vascular and the cerebrospinal fluid compartments. These results strongly suggest that we must consider time-window dependent results interpretation of USPIO-related signal changes in experimental stroke models.

 

Perfusion & Permeability Methodology

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  1704.     Is It Possible to Measure Water Exchange Using Conventional DCE-MRI?

David L. Buckley1, Lucy E. Kershaw1, Greg J. Stanisz2, 3

1University of Manchester, Manchester, UK; 2University of Toronto, Toronto, Canada; 3Sunnybrook Health Sciences Centre, Toronto, Canada

The importance of cellular-interstitial (transcytolemmal) water exchange (WX) in the measurement of contrast agent concentration using MRI is unclear. Early studies suggested that its influence could be avoided by appropriate choice of imaging sequence. More recent papers stress the importance of measuring WX (e.g. using a “shutter-speed” model). We studied human muscle and analyzed DCE-MRI data with a series of models encompassing the full range of WX scenarios. We concluded that the effect on our data was small and that conventional DCE-MRI is unsuitable for WX measurement.

                  1705.     Impact of AIF Errors on DCE-MRI Pharmacokinetic Parameters: Comparison of a High Temporal
                                 Resolution AIF and a Biexponential Description

Hai-Ling Margaret Cheng1, 2

1The Hospital for Sick Children, Toronto, Canada; 2University of Toronto, Toronto, Canada

A rapidly sampled arterial input function (AIF) is known to be essential for accurate DCE-MRI quantification. However, AIF measurement is subject to errors, particularly in the initial bolus phase, and it is unknown how these affect pharmacokinetic parameter accuracy. Simulations are performed to investigate the impact of AIF errors and to compare with a more slowly but carefully acquired biexponential AIF. Results show that a bolus amplitude error in a rapidly sampled AIF introduces significant error in the transfer constant and blood volume. When the bolus amplitude error exceeds 25%, the biexponential AIF provides more accurate parameter estimates.

                  1706.     Sampling Frequency Dependent Identifiability of Pharmacokinetic Parameters for Small and Large
                                 Molecular Contrast Agents

Karolien Jaspers1, 2, Mark J. Post2, Tim Leiner1, 2, Walter H. Backes1, 2

1Maastricht University Hospital, Maastricht, Netherlands; 2Maastricht University, Maastricht, Netherlands

The influence of the sampling rate and SNR on the identifiability of pharmacokinetic parameters, as defined in the Kety model, was investigated using Monte Carlo simulations, and the implications on designing a DCE-MRI protocol were discussed. In vivo measurements were used for construction of the arterial input function and noise level determinationThe precision and accuracy in parameter estimation at the lower frequencies was better for large molecular than for small molecular contrast agents This would allow lower sampling rates for large molecular contrast agents, and concomitant increase of spatial resolution, provided that sufficient SNR is obtained.

                  1707.     IntraVoxel Partially Coherent Motion (IVPCM) Technique: Application on Skeletal Muscle Microvasculature

Dimitrios C. Karampinos1, 2, Kevin F. King2, Bradley P. Sutton1, John G. Georgiadis1

1University of Illinois at Urbana-Champaign, Urbana, Illinois, USA; 2General Electric Healthcare, Waukesha, Wisconsin, USA

A reformulation of the IntraVoxel Incoherent Motion (IVIM) technique, based on the low b-value diffusion-weighted imaging regime, is proposed to characterize microcirculation of tissues perfused with partially coherent blood flow. The new methodology, termed IntraVoxel Partially Coherent Motion (IVPCM) technique, is suitable for tissues with oriented microvasculature and is currently applied to analyze certain geometrical parameters of the microvasculature of human calf muscle at rest. The proposed methodology has the unique capability of characterizing the anisotropy of microcirculation in vivo, in a manner analogous to the capability of high b-value diffusion to characterize the anisotropy of neural tracts.

                  1708.     The Effect of Blood Inflow and B1 Inhomogeneity on the Arterial Input Function in 3-D DCE-MRI

Caleb Roberts1, Ross A. Little1, Sha Zhao1, Yvonne Watson1, David L. Buckley1, Geoff J. Parker1

1The University of Manchester, Manchester, UK

An accurate individual measurement of the arterial input function (AIF) is required to achieve reliable estimates of microvascular characteristics in 3D dynamic contrast-enhanced MRI studies. Specific errors due to blood inflow and B1 inhomogeneity mean that the AIF measurement is challenging and location choice within the imaging slab is crucial. Using a combination of computer simulations, a flow phantom (including a “gold-standard” AIF), B1 mapping and clinical in vivo measurements we quantify these errors and demonstrate that accurate measurements of the AIF are achievable under certain conditions.

                  1709.     Portal Delay Estimation from DCE-MRI Liver Tissue Data : Feasibility and Effect on Vascular Parameter
                                Estimates

Matthew R. Orton1, James A. d'Arcy1, David J. Collins1, David Atkinson2, David J. Hawkes2, Martin O. Leach1

1Institute of Cancer Research, Sutton, UK; 2Univeristy College London, London, UK

Using a fixed input function for kinetic modelling of DCE-MRI data is a simple and robust technique, and in many cases gives more repeatable estimates than using a measured input function.  For DCE-MRI liver data a more complex dual input function is needed, and accurate determination of the delay between the arterial and portal components is critical for obtaining accurate vascular parameter estimates.  This abstract presents a technique for estimating the portal delay using only tissue data, and assesses the impact of this approach on estimates of the arterial-portal partition term (also known as the Hepatic Portal Index).

                  1710.     Limits of Accuracy in Assessing Vessel Permeabilities Using Permeability-Surface(PS)-Limited
                                Two-Compartment Models

Guido Correia Carreira1, Dirk Beyersdorff1, Lutz Lüdemann1

1Charité, Berlin, Germany

Aim of this work is to assess systematically possible over- and underestimation of vascular permeability, when using compartment models to fit DCE-MRI data of normal and tumor tissue in prostate. To this end, numerical diffusion simulations for several tissue models, describing the CM distribution process at the microscopic scale, are compared with a standard PS-limited (low permeability) two-compartment model. The results show a systematic underestimation of vessel permeabilty by the two compartment model of at least 3% to 7% up to 20% depending on the diffusion coefficient of tissue.

                  1711.     The Effect of RF Field Non-Uniformity on Tracer Quantification in DCE MRI of the Pelvis at 3 T

Cornelis A.T. van den Berg1, Reto Treier2, Jan G. Korporaal1, Greetje Groenendaal1, Fredy Visser1, Marco van Vulpen1, Uulke A. van der Heide1

1University Medical Center Utrecht, Utrecht, Netherlands; 2University of Zurich and ETHZ, Zurich, Switzerland

In DCE MRI of the pelvis the variable flip angle method is popular method to measure T1 changes allowing quantification of the bolus passage. In this study we investigated how flip angle deviations corrupt the tracer concentration quantification at 3 T. Using a B1 mapping method we found that RF field effects result in a highly inhomogeneous flip angle pattern.  Flip angles in the prostate deviate 10 to 15%, flip angles in the right Iliac Externa can be 30  to 40 % lower. This will result in a large overestimation of the AIF tracer concentration as demonstrated by simulations and measurements.

                  1712.     WITHDRAWN

 

Hyperpolarized 13C & Other Nuclei

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  1745.     In Vivo Carbon-13 Dynamic MRS and MRSI of Rat Liver with Hyperpolarized 13C-1-Pyruvate

Simon Hu1, 2, Albert P. Chen1, Matthew L. Zierhut1, 2, Robert Bok1, 2, Mark Van Criekinge1, Yi-Fen Yen3, Marie A. Schroeder4, Ralph E. Hurd3, Sarah J. Nelson1, 2, John Kurhanewicz1, 2, Daniel B. Vigneron1, 2

1University of California at San Francisco, San Francisco, California , USA; 2UCSF & UCB Joint Graduate Group in Bioengineering, San Francisco, California , USA; 3GE Healthcare, Menlo Park, California , USA; 4University of Oxford, Oxford, UK

Previous studies have demonstrated the ability to detect uptake and metabolism of hyperpolarized 13C  pyruvate through non-localized dynamic MRS spectra in normal rats. This study was designed to obtain and characterize hyperpolarized 13C dynamic spectra localized to the liver and to investigate differences between non-fasted and fasted rats. Following fasting, we observed significantly altered 13C-alanine levels in the liver, which agrees with prior biochemical studies showing elevated levels of alanine aminotransferase during fasting. This study demonstrated that hyperpolarized 13C MR can detect significant changes in liver metabolic states in vivo and may be valuable for liver disease state studies.

                  1746.     Pulse Sequence for Dynamic Volumetric Imaging of Hyperpolarized Metabolic Products

Charles H. Cunningham1, Albert P. Chen2, Michael Lustig3, Janine Lupo2, Duan Xu2, John Kurhanewicz2, Ralph E. Hurd4, John M. Pauly3, Sarah J. Nelson2, Daniel B. Vigneron2

1Sunnybrook Health Sciences Centre, Toronto, Canada; 2UCSF, San Francisco, California , USA; 3Stanford University, Stanford, California , USA; 4ASL, GE Healthcare, Menlo Park, California , USA

A spectral-spatial excitation pulse was designed to excite a single line of the spectrum resulting from metabolism of hyperpolarized carbon-13.  The pulse was implemented along with an echo-planar readout trajectory to give volumetric coverage every 3.5 seconds.  The pulse sequence was applied to measure the different lactate dynamics in different tissues in a normal rat model and a mouse model of prostate cancer.  The results suggest that significantly different dynamic curves can be observed in tumour vs. non-cancerous tissue.

                  1747.     Apparent T2 of 13C-Labeled Metabolites In Vivo

Yi-Fen Yen1, Patrick Le Roux2, Robert Bok3, Jim Tropp1, Albert Chen3, Vickie Zhang3, Matthew Zierhut3, 4, Mark Albers3, 4, Ilwoo Park3, 4, Sarah Nelson5, Dan Vigneron3, John Kurhanewicz3, Ralph Hurd1

1GE Healthcare, Menlo Park, California , USA; 2GE Healthcare, France; 3University of California, San Francisco, California , USA; 4Berkeley, California , USA; 5UCSF, San Francisco, California , USA

Apparent T2 relaxation time of 13C-labeled metabolites was measured for the first time in animals, following an injection of hyperpolarized 13C-pyruvate solution. Pyruvate and its metabolic products such as lactate, alanine and bicarbonate, were observed in the T2 measurements. A CPMG sequence was employed to acquire spectra at every spin echo for total of 8-10 seconds. The T2-decay curves were best described by multiple T2 components. The in vivo T2 results presented here are valuable for future sequence designs in13C metabolic imaging applications. The T2 information may also have diagnostic value as T2 may vary between healthy and diseased tissues.

                  1748.     First Studies with Hyperpolarized [2-13C]pyruvate in the Rat Brain

Isabelle Iltis1, Dinesh Kumar Deelchand1, Malgorzata Marjanska1, Christopher Nelson1, Kamil Ugurbil1, Pierre-Gilles Henry1

1Center for Magnetic Resonance Research, Minneapolis, Minnesota, USA

In this work, we successfully hyperpolarized [2-13C]pyruvate and measured hyperpolarized 13C signals in the rat brain in vivo following i.v. injection of the molecule. Resonances from [2-13C]pyruvate, [2-13C]pyruvate hydrate and [2-13C]lactate, but not from TCA cycle intermediates, were observed. The T1 relaxation time of [2-13C]pyruvate was on the order of 15 s in vivo.

                  1749.     Combined Reconstruction of Rosette Sampled Data for Hyperpolarised 13C Metabolic Imaging

Rolf F. Schulte1, Florian Wiesinger1, Ileana Hancu2

1GE Global Research, Munich, Germany; 2GE Global Research, Niskayuna, New York, USA

Metabolic imaging with hyperpolarised 13C requires rapid acquisition sequences in order to encode both spectrally and spatially with a high resolution. The rosette trajectory is one of the most efficient acquisition sequences with a high spectral selectivity, however at the cost of a high sensitivity towards B0 inhomogeneities. Including as much physical information as possible improves the robustness considerably. In this work, we combine coil sensitivities, B0 correction and chemical shifts in one reconstruction. The encoding model is extended by this information and solved with conjugate gradient iterative reconstruction. Simulations, in-vivo and in-vitro scans show promising results.

                  1750.     Parallel Imaging with GRAPPA CSI for Hyperpolarised 13C Metabolic Imaging

Rolf F. Schulte1, Arjun Arunachalam2, Kenneth M. Fish3, David B. Whitt3, Florian Wiesinger1, James Tropp4, Ileana Hancu2

1GE Global Research, Munich, Germany; 2GE Global Research, Niskayuna, New York, USA; 3GE Global Research, Niskayuna, USA; 4GE Healthcare, Menlo Park, California , USA

Metabolic imaging of hyperpolarised 13C1-pyruvate was combined with parallel image CSI acquisition and GRAPPA reconstruction. A custom-built, four-channel rat-coil was used for signal acquisition after injecting hyperpolarised 13C1-pyruvate in a rat. Data was acquired with a fully-sampled FID CSI sequence with a spatial and spectral resolution of 24x24 and 256, respectively. The spectral dimension was reconstructed by chemical-shift modelling (matrix inversion) to the three resonances (pyruvate, alanine/pyruvate-ester and lactate). One GRAPPA kernel was fitted from the k-space centre for the three resonances The data was artificially undersampled and then GRAPPA interpolated to yield the same metabolic maps as from the fully sampled data.

                  1751.     Sensitivity Mapping for Parallel Imaging of Hyperpolarized 13C Compounds

Daniel Blezek1, 2, Arjun Arunachalam1, David Whitt1, Kenneth Fish1, Ileana Hancu1

1GE Research, Niskayuna, New York, USA; 2Mayo Clinic, Rochester, Minnesota, USA

Coil sensitivity profiles for hyperpolarized 13C compounds may be acquired in phantoms prior to actual scanning.  Low coil loading permits profiles to be measured once for rigid geometry coils.  We have developed a method to register pre-acquired sensitivity profiles to 13C-pyruvate acquisition using fudical spheres rigidly affixed to the coil.  A 13C-acetate and 23Na phantom were constructed and imaged.  Using a custom 4 channel rat-sized coil, we compare 13C-pyruvate rat images reconstructed from fully sampled signals to SENSE recon using self-calibrated profiles(R=1.5), pre-acquired 13C-acetate(R=2) and 23Na profiles(R=2).  Parallel imaging results compare favorably with full reconstruction.

                  1752.     Accelerated Imaging of Hyperpolarized Carbon-13 Compounds

Arjun Arunachalam1, David Whitt1, Kenneth Fish1, Randy Giaquinto1, Ileana Hancu1

1GE Global Research Center, Niskayuna, New York, USA

The long scan time characteristic of traditional chemical shift imaging sequences (CSI) is a major limitation for metabolic imaging of hyperpolarized compounds. In this work, the ability to accelerate the spatial encoding process during a CSI scan of hyperpolarized compounds is demonstrated in vivo through parallel imaging. A hardware set up designed to acquire 13C signal data from multiple receivers simultaneously is presented and the ability to perform parallel imaging is demonstrated in vivo. The CSI data from the accelerated scans is reconstructed using self-calibrated SENSE, by using coil sensitivity maps obtained from the central region of k-space.

                  1753.     Hyperpolarized 13C MRI with a Triple-Frequency RF Coil

S. James Wood1, Brian K. Rutt1, Joseph Piel2, David B. Whitt2, Kenneth M. Fish2, W. Thomas Dixon2, Ileana Hancu2

1Robarts Research Institute, the University of Western Ontario,, London, Canada; 2GE Global Research Center, Niskayuna, New York, USA

Imaging 13C hyperpolarized compounds requires new MR hardware capabilities. 1H imaging is required for anatomical localization and shimming. Accurate flip angle calibration for 13C scans can be performed using natural abundance 23Na signal. We demonstrate here a triple-frequency RF resonant structure, which mitigates signal loss of previous designs and eliminates the need for multiple coils. In vivo, hyperpolarized 13C experiments are demonstrated where images are acquired sequentially at 1H, 23Na, and 13C frequencies without moving the coil or specimen.  Proton, sodium, lactate, and pyruvate images are acquired; as expected, high 23Na and 13C signals are visible over the kidneys.

                  1754.     Time-Resolved Metabolic Imaging in the Rat After Injection of Hyperpolarized 13C-1-Pyruvate at 3 Tesla

Dirk Mayer1, 2, Yi-Fen Yen3, Yakir S. Levin1, James Tropp3, Adolf Pfefferbaum, 12, Ralph E. Hurd3, Daniel M. Spielman1

1Stanford University, Stanford, California , USA; 2SRI International, Menlo Park, California , USA; 3GE Healthcare, California , USA

This work reports on the development of rapid time-resolved 13C spiral chemical shift imaging for the assessment of localized metabolic parameters. The sequence was tested at 3 Tesla on a phantom to measure the longitudinal relaxation constant of hyperpolarized 13C-1-pyruvate. In the in vivo application, the time course of pyruvate, lactate, and alanine were measured in the kidneys and the liver of a rat after tail vein injection 1 ml of hyperpolarized 13C-1-pyruvate.

                  1755.     Ultra-Fast in Vivo Metabolic Imaging in the Rat After Injection of Hyperpolarized 13C-1-Pyruvate at 3 Tesla

Dirk Mayer1, 2, Yi-Fen Yen3, Yakir S. Levin1, James Tropp3, Adolf Pfefferbaum, 12, Ralph E. Hurd3, Daniel M. Spielman1

1Stanford University, Stanford, California , USA; 2SRI International, Menlo Park, California , USA; 3GE Healthcare, California , USA

A fast spiral chemical shift imaging sequence has been developed for application in hyperpolarized 13C imaging. The sequence exploits sparse spectra and prior knowledge of resonance frequencies to reduce the measurement time by undersampling the data in the spectral domain. Multiple data sets having only frequency components within a certain bandwidth are reconstructed “in-focus” while others are severely blurred (“spectral tomosynthesis”). The sequence was applied to sub-second metabolic imaging of the rat in vivo after injection of hyperpolarized 13C-1-pyruvate.

                  1756.     Detection and Imaging of Hyperpolarized 6-Lithium in the Rat Brain in Vivo

Ruud Bernardus van Heeswijk1, Kai Uffmann1, Arnaud Comment1, Fiodar Kurdzesau1, 2, Chiara Perazzolo1, Cristina Cudalbu1, Sami Jannin1, J.A. Konter3, Patrick Hautle2, Ben van den Brandt2, Jacques J. van der Klink1, Gil Navon4, Rolf Gruetter1, 5

1Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; 2Paul Scherrer Institute, Villigen, Switzerland; 3Paul  Scherrer Institute, Villigen, Switzerland; 4Tel Aviv University, Tel Aviv, Israel; 5Universities of Lausanne and Geneva, Switzerland

This study focused on the feasibility and characterization of the usage of in vivo hyperpolarized lithium-6. Therefore, hyperpolarized lithium-6 chloride was infused in the rat femoral vein. Pulse-acquire as well as fast spectroscopic imaging were used to study the signal decay and spatial distribution of the lithium in the rat head. The relaxation time appeared to change over time from an initial 32 to 94 s and was detectable up to five minutes after dissolution. The spectroscopic imaging demonstrated that lithium appears to distribute in the brain.

                  1757.     A Simple, Low-Cost Device for Producing Hyperpolarized Heteronuclear Contrast Agents Using
                                Parahydrogen-Induced Polarization

Stephen Kadlecek1, Vahid Vadhat1, Robert V. Cadman1, Kiarash Emami1, John MacDuffie Woodburn1, Richard A. Guyer1, Masaru Ishii, 12, Jiangsheng Yu1, Hans Hyonchang Kim1, Warren Gefter1, Rahim R. Rizi1

1University of Pennsylvania, Philadelphia, Pennsylvania, USA; 2Johns Hopkins University, Baltimore, Maryland, USA

We present the essential design details for a device which produces hyperpolarized, 13C-containing solutions using the spin-order derived from parahydrogen.  The device provides flexible conditions for changing the target molecule and optimizing hydrogenation chemistry.  It is based on a small jet reactor, which is housed in a low-field, transmit-only NMR apparatus.  Preliminary results hyperpolarizing several 13C-labeled molecules is presented.

                  1758.     A Mobile DNP Polarizer for Clinical Applications

Kerstin Münnemann1, Christian Bauer2, Jörg Schmiedeskamp2, Hans Werner Spiess2, Wolfgang G. Schreiber1, Dariush Hinderberger2

1Mainz University Medical School, Mainz, Germany; 2Max-Planck-Institute for Polymer Research, Mainz, Germany

A mobile and low cost apparatus for DNP hyperpolarization is presented and its performance is demonstrated at room temperature and with three radical species. DNP enhancement factors for a triarylmethyl-based radical (TAM), TEMPOL and a polyelectrolyte spin-labeled with nitroxide radicals are measured as a function of mi-crowave power and the projected maximum enhancement factors are compared. The spin-labeled polyelectro-lyte shows the best DNP efficiency and 1H DNP enhancement factors up to -50 were observed. The results demonstrate that we are able to perform reliable DNP experiments in the proposed mobile apparatus and to ob-tain reasonably high 1H-DNP enhancements.

                  1759.     Hyperpolarization of Hetero Nuclei Via Adiabatic Field Cycling of Parahydrogenated Molecules

Bob C. Hamans1, Anna Andreychenko2, Sybren S. Wijmenga2, Arend Heerschap1, Marco Tessari2

1Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands; 2Radboud University Nijmegen, Nijmegen, Netherlands

Para-hydrogen induced polarization (PHIP) makes use of the macroscopic spin order contained in para-hydrogen gas (pH2) to produce hyperpolarization. Field cycling following a para-hydrogenation reaction allows for polarization transfer from the pH2 protons to other protons and hetero nuclei (e.g. 13C, 31P) of the hydrogenated substrates. A complete numerical simulation of this field cycling experiment is of great help in the selection of the optimal biologically interesting para-hydrogenatable substrates as well as for determining optimal field cycling conditions.

                  1760.     New Hyperpolarized Agents from Para-Hydrogenation of 13C-Labelled Butynoic Acid and Methylbutynoate

Alessandra Viale1, Daniela Santelia1, Francesca Reineri1, Roberta Napolitano1, Roberto Gobetto1, Silvio Aime1

1University of Torino, Torino, Italy

Para-hydrogenations of butynoic acid and its methyl ester (both protonated and deuterated) yield 13C signal enhancements in the reaction products, useful for 13C-MRI. Since the hydrogenation yield is higher for the ester and it is well soluble in water, it has been used to produce 13C MR images.

                  1761.     Method for Measuring Spin Relaxation During Production of Hyperpolarized 13C

Robert V. Cadman1, Stephen Kadlecek1, Kiarash Emami1, Richard A. Guyer1, Masaru Ishii, 12, Hans Hyonchang Kim1, Vahid Vadhat1, John MacDuffie Woodburn1, Jiangsheng Yu1, Rahim R. Rizi1

1University of Pennsylvania, Philadelphia, Pennsylvania, USA; 2Johns Hopkins University, Baltimore, Maryland, USA

We perform a numerical calculation of the effect of relaxation during a pulse sequence used to transfer spin order from protons in a state with total spin zero to a heteronucleus.  We propose that by measuring polarization resulting from a variety of pulse sequences, the relaxation time constants may be determined.  Knowledge of relaxation time constants would allow for better optimization of the pulse sequences.

                  1762.     Sensitivity Enhancement of Hyperpolarized Nuclei Through Polarization Transfer

Stephen Kadlecek1, Kiarash Emami1, Vahid Vadhat1, Jiangsheng Yu1, Richard A. Guyer1, Robert V. Cadman1, Masaru Ishii, 12, John MacDuffie Woodburn1, Hans H. Kim1, Warren Gefter1, Rahim R. Rizi1

1University of Pennsylvania, Philadelphia, Pennsylvania, USA; 2Johns Hopkins University, Baltimore, Maryland, USA

We demonstrate a technique for enhancement of hyperpolarized heteronuclear sensitivity by transferring polarization to a vicinal, higher-gyromagnetic ratio nucleus.  Phantom imaging results provide evidence that significant signal-to-noise gains can be achieved without sacrificing the advantages of a negligible background when imaging the heteronucleus directly.  Efficient transfer can be achieved despite the non-ideal nature (low-power pulse, unavoidable between-pulse delays) of a clinical MRI environment.

                  1763.     Mimicking the Role of NADH and FADH2 with Homogenous Hydrogenation Catalysts and Parahydrogen
                                Providing 13C-Hyperpolarized Biochemical Intermediates for 13C-MRI or 13C-MRS

Joachim Bargon1, 2, Ute Bommerich3, Matthias Stephan1, Rahim R. Rizi2

1University of Bonn, Bonn, Germany; 2University of Pennsylvania Medical Center, Philadelphia, Pennsylvania, USA; 3Leibniz Institute for Neurobiology, Magdeburg, Germany

The role of both enzyme-mediated biochemical redox systems, flavin adenine dinucleotide (FAD), the precursor molecule to 1,5-dihydro-FAD (FADH2), and nicotinamide adenine dinucleotide (NAD+) and its reduced form, NADH, can be mimicked by water-soluble homogeneous hydrogenation catalysts, which convert the unsaturated forms into their saturated derivatives. In connection with parahydrogen both proton and 13C-hyperpolarization result, which boosts the sensitivity of 13C-MRS and -MRI by some orders of magnitude. In this fashion various intermediates, for example of the degradation and synthesis of fatty acids and amino acids have been hyperpolarized successfully. Characteristic examples include glutamate, amino butyrate, succinate, fumarate, L-DOPA, etc.

                  1764.     Investigating the Metabolism of Glucose: An Alternative to 13C-Hyperpolarized Pyruvate

Joachim Bargon1, 2, Rahim R. Rizi, 12

1; 2University of Pennsylvania Medical Center, Philadelphia, Pennsylvania, USA

Water-soluble chiral homogeneous Rh(I)-hydrogenation catalysts containing ligands derived from the chiral pool of natural sugars hydrogenate glucose-derived unsaturated precursors to yield hyperpolarized derivatives boosting the sensitivity of 13C-MRI or 13C-MRS, providing an alternative to hyperpolarized pyruvate. The 1H-PHIP spectra reveal the formation of intermediate complexes consisting of the catalyst and the unsaturated substrate. The number of possible stereoisomers of these intermediates depends on the symmetry of the ligands used. The spectral analysis of these intermediates yields information about the enantiomeric purity of the hydrogenation product formed. For hyperpolarizing glucose this is of special importance since only D-glucose can be metabolized.

                  1765.     Providing 13C-Hyperpolarized Nicotine Derivatives for Use in 13C-MRI or 13C-MRS

Joachim Bargon1, Ute Bommerich2, Achim Koch3, Rahim R. Rizi4, Meike Roth3, Jorg Schmiedeskamp3, Hans W. Spiess3

1University of Bonn, Bonn, Germany; 2Leibniz Institute for Neurobiology, Magdeburg, Germany; 3Max-Planck Institute for Polymers, Mainz, Germany; 4University of Pennsylvania Medical Center, Philadelphia, Pennsylvania, USA

13C-hyperpolarized alkylated nicotines mimic neurotransmitters like acetylcholine, but unlike those they readily and hence quickly penetrate the blood-brain barrier. Nicotine derivatives are considered as medications to treat Parkinson's disease, Alzheimer's disease, schizophrenia, depression, anxiety or pain. On the other hand, nicotine serves an important role in provi-ding pleasure and relaxation. Due to its addictive properties, quitting smoking is difficult, even though the consequences of smoking health-wise are severe. 13C-hyperpolarized nicotines are a prerequisite applying 13C-MRI or 13C-MRS due to the low sensitivities of these methods. The required unsaturated precursors are readily synthesized. SIB-1509Y is a drug itself.

                  1766.     Observation of Anomalously Long-Lived Hyperpolarized C13 States in  Parahydrogen-Induced
                                 Polarization<

Aaron K. Grant1, Elena Vinogradov1

1Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA

Hyperpolarized contrast media based on nuclei such as 13C yield dramatic enhancements of signal-to-noise ratio in MRI. The comparatively short T1 relaxation time of the available agents presents a challenge to applications of hyperpolarization.  Recent observations have shown that certain quantum-mechanical spin states possess relaxation times significantly longer than T1 when they are stored under low field conditions.  Measurements in parahydrogen-induced polarization have demonstrated significant lifetime enhancements in homonuclear proton systems, but large enhancements have not been observed in heteronuclear systems.   Here we present observations in a heteronuclear system where a carbon in a ‘CH’ group possesses an anomalously long lifetime.

                 1767.     Conservation of Hyperpolarized Long-Lived States in Low Field: Theory and Experiment

Elena Vinogradov1, Aaron K. Grant1

1Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA

Hyperpolarized liquid-phase contrast media dramatically improve the sensitivity of MRI.  Although the signal enhancements achieved with hyperpolarization are dramatic, they are also short-lived owing to the comparatively short T1 relaxation times of the available agents.  Recent observations have shown that certain quantum-mechanical states can have lifetimes significantly longer than T1.  Here we present results of theoretical and experimental work on long-lived states in three- and four-spin systems at low field.   We document a long-lived state in hyperpolarized ethyl acrylate, and describe how a ‘bottleneck’ in the relaxation process accounts for the observed time dependence of NMR spectra from this compound.

                  1768.     MRI of Hyperpolarized 3He at 3T

Kevin Teh1, Nicola de Zanche2, Salma Ajraoui1, Matthew Clemence, Klaas Pruessmann2, Jim M. Wild1

1University of Sheffield, Sheffield, UK; 2University and ETH Zürich, Zurich, Switzerland

The optimum B0 field strength for hyperpolarised (HP) MRI experiments is the subject of some discussion. The non-Boltzmann polarisation (achieved here with laser optical pumping) makes the magnetisation independent of B0, and low field MRI becomes a realistic possibility. Furthermore the field inhomogeneity at high B0 in the lungs makes the use of higher fields for lung imaging more challenging. Nevertheless, MRI manufacturers are shifting their multinuclear engineering focus on to higher B0 systems and engineering quality as well as electromagnetic physics will ultimately determine SNR in practice. The objective of this work was to investigate the feasibility of HP 3He MRI at 3T on a whole body system. The engineering aspects of upgrading our 3T system for 3He transmit receive are presented. Preliminary imaging results and SNR comparisons are made with data acquired at 1.5T with non-lossy 3He samples and coils of the same size and geometry.

                  1769.     Radiation Damping as a Diagnostic Tool for 3He Polarimetry in Optical Pumping Cells

Steven R. Parnell1, 2, Steven Boag2, Max Skoda2, Chris D. Frost2, Jim M. Wild1

1University of Sheffield, Sheffield, UK; 2Rutherford Appleton Laboratories, UK

For hyperpolarised 3He, accurate measurement of the polarisation is necessary. In-situ polarimetry of gas in the cell typically relies on small tip angle NMR from a coil close to the cell. In this work we investigate the effects of the high magnetisation on the observed FID from the optical pumping cell in both the high and low energy states and the effect of radiation damping on the observed total magnetisation.

                  1770.     Pulmonary Oxygen Mapping with 3He MRI at Very-Low-Field

Ross William Mair1, Rachel Nora Scheidegger1, 2, Leo Lee Tsai, 23, Matthew Scott Rosen1, 4, Ronald Lee Walsworth1, 4

1Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA; 2Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, USA; 3Harvard Medical School, Boston, Massachusetts, USA; 4Harvard University, Cambridge, Massachusetts, USA

The partial pressure of oxygen in the lung may be derived from the attenuation of the 3He MRI signal, if the RF flip-angle is precisely known. In clinical MRI systems this measurement is non-trivial, due to coil-loading effects of different human subjects and the B1 inhomogeneity of RF coils used at high field. Therefore, flip-angle calibrations are incorporated into every measurement. We employ an open-access, very-low-field human MRI system to study posture-dependent effects on pulmonary function.  Operation of this system at 210 kHz has resulted in a simplification of the pulmonary oxygen measurement technique in comparison to high-field methods.

                  1771.     High Production of Hyperpolarized Helium-3: Commercial Prototype

Iulian C. Ruset1, 2, David Watt1, Jan Distelbrink1, Adam Straub1, John Brackett1, Edward J. Kotkowski2, Chad D. Everbeck2, Korac MacArthur1, Alex J. Johnston2, Peter L. Conti2, F.W. W. Hersman1, 2

1Xemed LLC, Durham, New Hampshire, USA; 2University of New Hampshire, Durham, New Hampshire, USA

We present a commercial prototype for the high-production of hyperpolarized helium-3. The system is based on hybrid-alkali optical-pumping using kilowatt laser power. The polarizing cell is a large eight liter cylinder placed inside a pressure aluminum vessel which minimizes the stress on the glass. A gas line designed to minimize polarization losses and alkali diffusion allows for helium removal and renewal. The system is envisioned to produce 100 liters/day at 70% hyperpolarized helium-3. Preliminary tests confirmed the feasibility of the system. Polarization was limited to few percent by the low relaxation time of the Pyrex cell used. Improvements are underway.

                  1772.     Accelerated 3D Imaging of Oxygen Partial Pressure Using Projection Acquisition and Constrained
                                 Reconstruction

Rafael Luis O'Halloran1, James Hartman Holmes1, Sean Bedillion Fain1

1University of Wisconsin, Madison, Wisconsin, USA

A 3D stack-of-stars acquisition for oxygen partial pressure and flip angle parametric mapping in hyperpolarized helium-3 MRI is presented, validated in a phantom and demonstrated in a healthy volunteer. The acquisition provided 10 axial slices at 16 distinct time-points within a 16 s breath-hold. Measured oxygen pressures matched previously observed values in human lung and demonstrated the known anterior/posterior dependence in the supine position.

                  1773.     Evaluation of Dynamic Lung Function Using Non-Equilibrium Xenon Uptake Spectroscopy (NEXUS)

Kai Ruppert1, Jaime F. Mata2, Talissa Altes1, James R. Brookeman2, Klaus D. Hagspiel2, John P. Mugler III2

1The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA; 2University of Virginia, Charlottesville, Virginia , USA

Non-Equilibrium Xenon Uptake Spectroscopy (NEXUS), an extension of a commonly-used hyperpolarized xenon-129 MRS pulse sequence, might provide unique insights into the lung-function dynamics of a freely breathing subject that far exceed those of conventional spirometry. For instance, the gas transit time to travel to the alveolar gas-exchange sites might become an indicator of small airway disease. Other applications for NEXUS might include a free-breathing exam in children who cannot perform forced respiratory maneuvers. Also, with a temporal resolution of 30ms or better, which is much greater than that of any existing technique, not even a breath hold would be required.

                  1774.     Temperature-Sensitive Imaging by Means of Exchangeable Functionalized 129Xe

Monica A. Smith1, 2, Leif Schröder1, 2, Tyler Meldrum1, 2, Thomas J. Lowery1, 2, Alexander Pines1, 2, David E. Wemmer1, 2

1University of California, Berkeley, Berkeley, California , USA; 2Lawrence Berkeley National Laboratory, Berkeley, California , USA

Recent advances using functionalized 129Xe biosensors and hyperpolarized chemical exchange saturation transfer (HYPER-CEST) have overcome some of the intrinsic limitations when using 129Xe as a contrast agent, but additional gains in sensitivity are required for use of these methods in vivo.  Here, the effect of increasing the temperature of the system was investigated.  It was shown that HYPER-CEST contrast increased when the temperature was increased from 26 C to 32 C.  Preliminary data suggests that additional contrast is achievable at body temperature, which holds promise for in vivo applications.

                  1775.     Absolute Quantification of Pulmonary Perfusion Using Intravenous Injection of Hyperpolarized 129Xe

Harald E. Möller1, Bastiaan Driehuys2, James Pollaro2, Laurence W. Hedlund2

1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; 2Center for In Vivo Microscopy, Durham, North Carolina, USA

Recently, a means of lung perfusion imaging based on intravenous injection of hyperpolarized 129Xe dissolved in saline was proposed. Combination of such images with information obtained from serial gas-phase spectroscopy allows quantification of global lung perfusion. This information that can be used for scaling the image to obtain maps of regional lung perfusion in absolute units.

                 1776.     Hyperpolarized Xenon at 10 Liters Per Hour for Diagnostic MRI

Jan Distelbrink1, Jeff Ketel1, David Watt1, Adam Straub1, Iulian C. Ruset1, 2, Walt Porter1, Stephen Ketel1, John Brackett1, Aaron Hope1, Korac MacArthur1, Silviu Covrig2, F.W. W. Hersman1, 2

1Xemed LLC, Durham, New Hampshire, USA; 2University of New Hampshire, Durham, New Hampshire, USA

We present a compact system for high polarization, high volume (50% at 10 liters/hr) production of hyperpolarized xenon. Preparations to build production units have started. The system is based on the existing 1 liter/hr Xemed XeBox-B polarizer. Its 2” diameter glass column was replaced by a 6” square copper column for increased gas flow and dissipation of heat from the 800 Watt wavelength narrowed CW laser. An on-board computer controls the polarizer. Automated operation is facilitated by a web-based interface. Compliance with FDA 21 CFR 210 and 21 CFR 211 is anticipated.

 

Diffusion: Artifacts, Phantoms, QA, Reproducibility

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  1818.     Testing the Reproducibility of Diffusion Tensor Imaging at 3.0T

Jesper Frandsen1, Leif Østergaard1, Eva B. Vedel Jensen2

1Aarhus University Hospital, Aarhus C, Denmark; 2Aarhus University, Aarhus C, Denmark

From Diffusion Tensor Imaging (DTI) scalar indices such as apparent diffusion coefficient (ADC) and fractional anisotropy (FA) can be extracted. This indices are often used for comparing groups of healthy controls to groups with neurodegenerative deceases. In this study we have performed DTI on the same subject 20 times within few days to examine the reproducibility of these indices on a 3.0T scanner.

                  1819.     Quantitative Evaluation of  Diffusion Weighted-MRI Phantoms

Wilhelmus LPM Pullens1, 2, Alard Roebroeck3, Rainer Goebel3

1Maastricht University, Maastricht, Netherlands; 2Brain Innovation BV, Maastricht, Netherlands; 3Maastricht University, Netherlands

This paper presents phantoms for qualitative and quantitative validation of diffusion weighted MRI and fiber tracking. The aim is to construct a phantom with properties (T2 and anisotropy) similar to human white matter , combined with the possibility to create different geometries, to be measured with clinical protocols. Phantoms show higher perpendicular versus parallel ADC, as well as exponential signal decay when b-value is increased. FA is in a similar range as FA in human white matter. The phantom can be used for validation of fiber tracking; the construction method is suitable for crossing or kissing geometries at various angles.

                  1820.     Effects of Motion on Clinical Diffusion Tensor Imaging

Rob Hendrikus Tijssen1, Jacobus F. Jansen2, Walter H. Backes2

1Eindhoven University of Technology, Eindhoven, Netherlands; 2Maastricht University Hospital, Maastricht, Netherlands

In DTI, the gradient sampling scheme affects the propagation of image noise. Various optimized schemes have been proposed. However, these schemes are not immediately available in a clinical setting. Additionally, subject motion may have a considerable effect. This work assesses six clinically available gradient schemes by in vivo analyses and computer simulations. Our data show that, like image noise, motion effects are dependent on the sampling scheme. Whereas schemes with medium and high angular resolution showed similar results, gradient schemes with only six gradient directions demonstrated a considerably lower reproducibility and incur positive bias in the presence of motion.

                  1821.     Interpolation and Regularization of Diffusion Tensors Along Geodesics

Jaime E. Cisternas1, Marcelo Gálvez2, Gonzalo Rojas2, Takeshi Asahi2

1Universidad de los Andes, Santiago, Chile; 2Universidad de Chile, Santiago, Chile

The processing of diffusion tensor imaging (DTI) and tractography involve a number of steps, such as the registration, the estimation and the smoothing of tensor fields. These procedures implicitly rely on a measure to compare two or more tensors as well as on a continuous transformation of tensors.Several strategies for measuring distances between tensors have been proposed, some of them inspired from sophisticated mathematics and some others aiming at fast computations. Here we propose a simple theoretical framework to separate the problem into two parts: the first considers the shape of tensors, and the second their orientation. We illustrate the application of the interpolation and the regularization methods built from such a distance using a synthetic example and a DTI scan from a fiber phantom.

                  1822.     Towards a Diffusion Standard Ruler: Rigid Diffusion Phantom

Koji Sakai1, 2, Takashi Azuma1, Susum Mori2, Koji Koyamada1, Sadami Tsutsumi1

1Kyoto University, Kyoto, Japan; 2Johns Hopkins University, Baltimore, Maryland, USA

Anisotropy phantom for DTI studies is much needed for calibration of multi-center studies. Ideally, we can control the degree of anisotropy and the phantom is stable and mass-producible. In this paper, we introduce a DTI phantom based on channeled silicon plates. We demonstrate that the water diffusivity and anisotropy can be controlled by changing the channel depth and the anisotropy can be as high as 0.8. Interestingly, we observed axial diffusivity higher than free diffusion, posing us an interesting question about the interpretation of DTI results. Quality control for the production is a current issue to make this phantom available.

                 1823.     The Impact of Robust Tensor Estimation on Voxel-Wise Analysis of DTI Data

Daniel Jon Peterson1, Bennett A. Landman2, Laurie E. Cutting1, 2

1Kennedy Krieger Institute, Baltimore, Maryland, USA; 2Johns Hopkins School of Medicine, Baltimore, Maryland, USA

Methods of robust diffusion tensor estimation, like RESTORE, have been shown to decrease the effect of artifacts in a single subject. Here we demonstrate the impact of RESTORE on a voxel-wise group analysis of DTI data, using Cerebellar Ataxia as a sample condition. In a voxel-wise statistical comparison of the difference in FA between controls and patients, RESTORE was found to decrease the number of small areas of significance that are likely to be spurious. Additionally, a high number of outliers were found in regions vulnerable to artifacts, and RESTORE was shown to alter FA in a spatially heterogeneous manner

                  1824.     How Reliable Are Diffusion Tensor Spectroscopy Measures of Metabolite Diffusion?

Jacob Ellegood1, Chris C. Hanstock1, Christian Beaulieu1

1University of Alberta, Edmonton, Canada

Diffusion tensor spectroscopy (DTS) of metabolites in human brain could provide novel information, but it is challenging given low apparent diffusion coefficients (ADC) and poor signal-to-noise.  Too much variability in measured ADC with diffusion gradient direction could artificially inflate fractional anisotropy (FA) values, particularly at low ADC, and make isotropic regions appear anisotropic. More accurate measurements could result from the use of higher b values (5000 s/mm2) than that more commonly used in DTS (1500-2000 s/mm2). The sensitivity of FA was shown to be true for a range of isotropic alcohols with low ADC and in human occipital gray matter.

                  1825.     Non-Linearity in Diffusion-Gradient Induced Eddy-Current Fields in a Head Only 3T Scanner

Pablo Velasco1, Souheil J. Inati1

1NYU, New York, New York, USA

We investigated the linearity of the eddy-current induced fields in diffusion-weighted imaging in a head-only 3T scanner.  We find that the short-time eddy-current fields scale with the amplitude of the diffusion gradients, but the long-time eddy-current induced fields do not.  This non-linearity implies that a full characterization of the spatio-temporal distribution of the field is needed for optimal image quality in DWI.

                  1826.     Employing Bootstrapping Methods to Examine the Need for Pulse Triggering in Diffusion-Weighted
                                 Imaging

Zoltan Nagy1, Chloe Hutton1, Daniel C. Alexander1, Ralf Deichmann1, 2, Nikolaus Weiskopf1

1University College London, London, UK; 2University of Frankfurt, Frankfurt, Germany

Employing pulse triggering is in wide-spread use for diffusion weighted imaging since the demonstration that this reduces image variance. However, gradient systems have improved in speed/strength and parallel imaging methods have further reduced the acquisition time. We employed bootstrapping statistical methods to establish whether pulse triggering reduces the variance in diffusion-weighted datasets acquired using recent gradient systems. To this effect we found no significant advantage resulting from the use of pulse triggering. This offers the possibility for a significant reduction in acquisition time or the chance for multiple acquisitions but should be determined individually for each scanner/site/patient group.

                  1827.     Robust Diffusion Tensor Estimation by Maximizing Rician Likelihood

Bennett Allan Landman1, Pierre-Louis Bazin1, Jerry L. Prince1

1Johns Hopkins University, Baltimore, Maryland, USA

Maximum likelihood tensor estimation based on a full treatment of Rician distributed MR intensities (DTEMRL) has been recently shown to significantly improve DTI reliability in clinical and high SNR applications. However, DTEMRL suffers from low reliability in low SNR applications. Here, we present a robust maximum a posteriori generalization (rDTEMRL) of the DTEMRL technique by inclusion of noise level Bayesian priors and a robust likelihood function.  In simulation, the new method is shown to offer superior reliability and robust performance in the presence of artifact. In an empirical study, rDTERML improves the consistency of diffusion tensor estimates.

                  1828.     Dealing with Artifacts Induced by Spike Noise in Diffusion Tensor Imaging

Jonathan S. Jackson1, Elvina M. Chu1, Mara Cercignani2, Maria A. Ron1, Claudia A. Wheeler-Kingshott1

1UCL Institute of Neurology, London, UK; 2Fondazione Santa Lucia, Rome, Italy

DTI data can be affected by many types of artifact. In a case where one out of 68 diffusion weighted images was affected by spike noise, the FA map showed an artifactual 5% variation in white matter, which is of the order of changes induced by pathology. The effect of this artifact can be removed through a combination of manual editing and the RESTORE algorithm proposed by Chang et al. (2005).

                  1829.     Comparison of EPI Distortion Correction Methods in Diffusion Tensor MRI

Minjie Wu1, 2, Alan S. Barnett1, Stefano Marenco1, Lindsay Walker1, Herve Lemaitre1, Carlo Pierpaoli1

1National Institutes of Health, Bethesda, Maryland, USA; 2University of Pittsburgh, Pittsburgh, Pennsylvania, USA

EPI distortions in diffusion-weighted images (DWIs) degrade the quality of brain DT-MRI. In this study, we evaluate the performance of two methods for correcting EPI distortions: the standard method based on B0 field mapping (B0M) and a newly proposed b-spline image registration method (BSP). We found that both methods can effectively reduce the EPI geometric distortion improving the anatomical accuracy of quantities derived from the diffusion tensor. However, the BSP algorithm consistently provides better correction for rostral brain regions while the B0M method performs better at the base of the brain, including temporal lobes, brainstem, and cerebellum.

                  1830.     Robust DTI Noise Level Estimation Improves RESTORE Tensor Estimation

Bennett Allan Landman1, Pierre-Louis Bazin1, Jerry L. Prince1

1Johns Hopkins University, Baltimore, Maryland, USA

We present a noise level estimation method that specifically addresses the challenges of diffusion tensor imaging (DTI) data. Our method utilizes two repeated DTI acquisitions, which are commonly acquired in clinical DTI protocols, to identify the spatially varying noise profile. The novel noise level estimates significantly improve accuracy of the RESTORE tensor estimation method when compared with conventional noise level estimation approaches. This method is robust to background signal suppression, spatial noise correlation, and coil sensitivity variability.

 

Perfusion & Permeability: Dynamic Contrast Enhanced Methods

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  1882.     Comparison of Perfusion Analysis in DCE-MRI of Brain Tumors with and Without T1-Quantification

Michael Ingrisch1, Steven Sourbron1, Karin Herrmann1, Maximilian Reiser1, Michael Peller1

1Klinikum Großhadern, Munich, Germany

Quantification of tissue perfusion and permeability parameters from DCE-MRI bolus-tracking data requires a measurement of the tracer concentration, which can be obtained from a measurement of pre-contrast tissue relaxation rate. This study compares the effect of T1-quantification on the perfusion parameters measured with DCE-MRI in brain metastases, to a simpler approach based on relative signal enhancement. Contrary to expectations, values of perfusion and permeability parameters are increased after T1-quantification. Simulations confirm that T1-quantification may introduce additional errors if the actual flip angle is not precisely known.

                  1883.     Measuring Cerebral Blood Flow and Blood-Brain-Barrier Leakage with DCE-MRI at 3T

Steven Sourbron1, Michael Ingrisch1, Axel Siefert1, Maximilian F. Reiser1, Karin Herrmann1

1Ludwig-Maximilian-University Munich, Munich, Germany

DSC-MRI measurement of perfusion and permeability in the brain suffers from serious quantification issues. Here we propose an alternative in the form of an optimized DCE-MRI protocol at 3T, and evaluate it using measurements in normal tissue and in brain tumors. Maps of CBF approach the quality of DSC-MRI images. AIF selection is straightforward, CBF in Grey Matter agrees with gold-standard values, and Extraction Flow can be quantified from the same data. We conclude that DCE-MRI at 3T provides a viable alternative to DSC-MRI for the quantification of cerebral perfusion and permeability in a wide range of applications.

                  1884.     Correction of Partial Volume Effects in Plasma Time Curve for Tracer Kinetic Analysis in DCE-MRI

RKS Rathore1, A Singh1, RK Gupta2, M Haris2, SK Verma1, A Purwar1, G Bayu1, MK Sarma1, J Singh1, S Agarwal1, DKS Rathore1

1Indian Institute of Technoloky, Kanpur, Kanpur, India; 2SGPGIMS, Lucknow, India

Tracer kinetic analysis of DCE-MRI data requires the plasma concentration time curve. The use of individually measured plasma curve (if accurately measured) has advantages over standard plasma curve as it improves accuracy of measurements. In a brain DCE-MRI data the partial volume effect (PVE) is the main problem in the measurement of accurate plasma curve. The automated AIF extraction method proposed here is similar to that described by Rijpkema et al., 2001 and Parker et al., 2006, but it additionally corrects for the PVE, and also does an automatic estimation of bolus arrival time (BAT) using PL model.

                  1885.     Comparison of Arterial Input Functions Obtained from Unlabeled- And 14C-Labeled-Gadolinium-
                                 Diethylenetriaminepentaacetic Acid and Its Application in MRI Estimation of Blood-To-Brain Influx
                                 and Cerebral Microvascular Blood Space

Kishor Karki1, 2, Tavarekere N. Nagaraja1, James R. Ewing1, 2, Joseph D. Fenstermacher1, Robert A. Knight1, 2

1Henry Ford Hospital, Detroit, Michigan, USA; 2Oakland University, Rochester, Michigan, USA

The arterial input function (AIF) of contrast agent (CA) is required to calculate blood-to-brain transfer constant (Ki) and cerebral microvascular blood volume (vD). We compared AIFs from MRI and quantitative autoradiography studies using identically prepared CAs viz., unlabeled- and 14C-labeled- gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA and Gd-[14C]DTPA, respectively) in a rat model of transient focal cerebral ischemia to test our hypothesis that the reconstructed AIF generated from Gd-[14C]DTPA can be used to correct MRI-derived estimates of Ki and vD. For the regions with a leaky BBB, the reconstructed MRI-AIF produced significantly lower values of Ki and vD than did the original.

                  1886.     An MRI Estimate of Vascular Permeability in 9L Cerebral Tumor Agrees with Those of Quantitative
                                 Autoradiography

James Russell Ewing1, 2, Tavarekere N. Nagaraja1, ramesh paudyal3, Hassan Bagher-Ebadian1, 4, Knight Robert1, Ledbetter Karyn1, Joseph D. Fenstermacher1

1Henry Ford Hospital, Detroit, Michigan, USA; 2Oakland University, Rochester, Michigan, USA; 3oakland University, rochester, Michigan, USA; 4Amir-Kabir University of Technology, Tehran, Iran

In 15 rats implanted with 9L tumor, the vascular transfer constant (K1 or Ktrans) was assessed by MRI means, and then, in a terminal experiment, by quantitative autoradiography (QAR).  Essentially the same indicator, albumin, tagged with Gd in the MRI, and with 125I in the QAR, was used.  The K1’s estimated by the two techniques were in agreement.

                  1887.     Vascular Permeability to Gd-DOTA and USPIO in C6 and RG2 Rat Glioma Models

Marine Beaumont1, 2, Benjamin Lemasson, 13, Régine Farion1, 2, Christoph Segebarth1, 2, Chantal Remy1, 2, Emmanuel Luc Barbier1, 2

1INSERM U836, Grenoble, France; 2Université Joseph Fourier, Grenoble Institut des Neurosciences, UMR_S836, Grenoble, France; 3Oncodesign Biotechnology, Dijon, France

DCE-MRI provides insight into vascular permeability of tumors. Typically, a contrast agent such as Gd-DOTA is used and data are analyzed using classical pharmacokinetic models to obtain microvascular parameters. For further characterization, intravascular contrast agent (USPIO) can be used to determine blood volume and vessel size index under stationary conditions. In view of eventually combining these two approaches into a single imaging protocol, we evaluated whether the USPIO remains intravascular during a DCE-MRI protocol. DCE-MRI experiments using Dotarem® and Sinerem® were therefore performed on two brain tumor models. The presence of macrophages, potential transporters of iron, was equally investigated.

                  1888.     Quantitative Permeability MRI in Acute Ischemic Stroke: How Long Do We Need to Scan?

Logi Vidarsson1, Fang Liu1, Brandy Moran1, David Mikulis2, Andrea Kassner1

1The Hospital for Sick Children and the University of Toronto, Toronto, Canada; 2The Toronto Western Hospital, Toronto, Canada

Dynamic T1-weighted MR permeability imaging with subsequent pharmacokinetic modeling, provides valuable information on blood-brain-barrier (BBB) integrity in acute ischemic stroke (AIS) and can lend insight into which AIS patients later develop hemmorrhage. However, the relatively long scan duration (5 min) is problematic in critically ill AIS patients. In this work we examine the effects of reducing scan time on quantitative permeability (KPS). Our results indicate that the uncertainty in permeability estimates increases as less and less data is used for analysis.

                  1889.     Which Voxels Should Be Analysed in DCE-MRI Studies of Anti-Vascular/angiogenic Compounds?

Chris J. Rose1, James P. O'Connor1, Brandon Whitcher2, Geoff J. Parker1

1The University of Manchester, Manchester, UK; 2GlaxoSmithKline, London, UK

This abstract describes a problem with the way that average Ktrans is often computed in the context of studies of anti-vascular/angiogenic compounds, provides a simple geometrical explanation, proposes a solution and compares the statistical power of tests based on the two methods. Tumours often have an enhancing rim, thought to correspond to increased angiogenic activity. In such cases, we found that a given statistical power can be achieved using a smaller sample size when computing a voxel-wise average Ktrans from the enhancing region only, compared to computing the voxel-wise average Ktrans from all tumour voxels.

                  1890.     Quantifying Spatial Heterogeneity in Dynamic Contrast-Enhanced MRI Parameter Maps

Chris J. Rose1, Sam Mills1, James P. O'Connor1, 2, Gio Buonaccorsi1, Caleb Roberts1, Yvon Watson1, Sha Zhao1, Brandon Whitcher3, Gordon Jayson2, Alan Jackson1, Geoff J. Parker1

1The University of Manchester, Manchester, UK; 2Christie Hospital NHS Trust, Manchester, UK; 3GlaxoSmithKline, London, UK

In DCE-MRI-based drug trials, each tumour voxel is summarised using model-free or tracer kinetic model parameters. The tumour is summarised by average parameter value, but this fails to capture heterogeneity information. Heterogeneity has been described using histograms (for example), but previous methods discard all spatial information. This may be important to the correct interpretation of the structure of DCE-MRI parameter maps. We have developed statistics that consider parameters’ values and spatial locations. We show that these are sensitive to known drug effects and may predict the grade of gliomas (which are determined in histology by spatial heterogeneity).

                  1891.     Assessing Drug Effects by Comparing DCE-MRI Parameter Maps Using the Earth Mover's Distance Metric

Chris J. Rose1, Heather Reynolds1, James P.B. O'Connor1, 2, Sue Cheung1, Yvon Watson1, Gordon Jayson2, Brandon Whitcher3, Geoff J. Parker1

1The University of Manchester, Manchester, UK; 2Christie Hospital NHS Trust, Manchester, UK; 3GlaxoSmithKline, London, UK

In DCE-MRI drug trials, current practice involves computing parameters such as Ktrans at each tumour voxel and then summarising the tumour by the median Ktrans value. The change in median values before and after treatment is used as a dissimilarity measure. Drug effects are often observed in particular locations within the tumour. Median Ktrans may be insensitive to these heterogeneous local changes as they neglect the spatial location of parameters. This abstract describes how drug effects can be assessed by using the cost of matching pre- and post-treatment parameter maps using the Earth Mover's Distance metric. 

                  1892.     Fusion of Dynamic Contrast Enhanced (DCE) Perfusion Metrics with DTI Metrics Results in Better
                                Assessment of Corticospinal Tract Infiltration in Malignant Gliomas

Rakesh K. Gupta1, Mohammad Haris1, Mazhar Husain2, Sanjay Verma3, Anup Singh3, Abhishek Yadav1, Nuzhat Husain2, Ram Kishore Singh Rathore3

1Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India; 2CSM Medical University, Lucknow, India; 3Indian Institute of Technology, Kanpur, India

Edema surrounding the malignant tumors is a morphological sign of tumor infiltration in the adjacent white matter. Diffusion tensor imaging has been used to differentiate the infiltrative white matter tract from the normal white matter tract. The Malignant gliomas have shown high value of cerebral blood volume (CBV), cerebral blood flow (CBF), permeability (ktrans) and leakage (ve). In the current study, we fused DTI indices maps with perfusion maps with a hypothesis that the perfusion maps when combined with DTI maps should able to separate the edematous region from infiltrating fibers which may not be possible alone on DTI.

                  1893.     DCE-MRI for Assessment of Effects of Anti-Angiogenic Therapy: Comparison of the Transfer Constant
                                (Ktrans) to Blood Permeability Derived by a Distributed Parameter Model

Choon Hua Thng1, Tong San Koh2, Septian Hartono1, 2, Helmut Rumpel3, James Boon Kheng Khoo1, Albert Su Chong Low3, Ai Bee Ong4, Norita Sukri4, Bee Choo Tai5, Ross Soo4, Rod A. Humerickhouse6, Boon Cher Goh4

1National Cancer Centre, Singapore, Singapore; 2Nanyang Technological University, Singapore; 3Singapore General Hospital, Singapore; 4National University Hospital, Singapore; 5National University of Singapore, Singapore; 6Abbott Laboratories, North Chicago, Illinois, USA

Dynamic contrast enhanced MRI (DCE-MRI) with tracer kinetic modeling has been proposed as a biomarker of angiogenesis imaging. Generalized kinetic (GK) model  and uptake integral approach are commonly used DCE-MRI models whose representative parameters are Ktrans and initial area under the signal-time curve (IAUC), respectively. The distributed parameter (DP) model is a DCE-MRI model that enables derivation of blood flow and capillary permeability-surface area product (PS) independently. We aim to study the DP model as an alternative method of angiogenesis assessment and correlate the above parameters to drug exposure and patient outcome in a Phase I anti-angiogenic trial.

                  1894.     Effect of Image Acquisition Protocol on Vascular Parameter Estimates from DCE-MRI Liver Data

Matthew R. Orton1, David J. Collins1, David J. Hawkes2, David Atkinson2, Martin O. Leach1

1Institute of Cancer Research, Sutton, UK; 2Univeristy College London, London, UK

Since the liver is a highly vascularised organ, accurate pharmaco-kinetic models for DCE-MRI liver data must include a plasma fraction.  The temporal resolution of the acquired data must therefore be fast enough to allow this feature to be observed.  This work assesses the impact on the vascular parameter estimates of acquiring two volumes per breath-hold in a liver imaging protocol instead of one.

 

Imaging in Stroke: Clinical Studies

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                 1948.     Biomarkers of Cerebral Microvascular Angiopathy in Healthy Subjects at Risk of Stroke

Alan Jackson1, Johann Selvarajah2, Marietta Scott3, Sharon Hulme3, Rachel Georgiou3, Nancy Rothwell3, Pippa Tyrell4

1University of Manchester, Withington, UK; 2Greater Manchester Neuroscience Centre, Salford, UK; 3University of Manchester, Manchester, UK; 4Greater Manchester Neuroscience Centre, Manchester, UK

We have examined 2 imagign biomarkers of cerebral microvascular disease in normal elderly subjects at risk of stroke. Both dilated Virchow Robin Spaces and Arterial-CSF pulsewave propogation rates were significantly different in subjects at risk and subjects not at risk whilst white matter lesion distribution was not significantly different.

                  1949.     Detection of Crossed-Cerebellar Hypoperfusion in Acute Stroke Using Perfusion-Weighted MRI

Jonathan T. Kleinman1, Doris D.M. Lin1, Robert J. Wityk1, Rebecca F. Gottesman1, Andrew W. Lee1, Peter B. Barker1

1Johns Hopkins University, Baltimore, Maryland, USA

Crossed cerebellar diaschisis (CCD) is commonly reported in the nuclear medicine literature in studies of acute stroke. This abstract reports on the incidence of CCD (hypoperfusion) in acute stroke as detected by MR perfusion imaging.

                  1950.     Correlation of Acute Perfusion Lesion Volumes with Neurological Deficits Depends on Deconvolution
                                Algorithm

Ona Wu1, Jie Lu1, Vicky J. Tiglias1, Christian A. Holt2, Thomas Benner1, William A. Copen2, E Murat Arsava1, Hakan Ay1, Pamela W. Schaefer2, R Gilberto Gonzalez2, Lee H. Schwamm2, Aneesh B. Singhal2, A Gregory Sorensen1

1Massachusetts General Hospital, Charlestown, Massachusetts, USA; 2Massachusetts General Hospital, Boston, Massachusetts, USA

A consecutive series of acute stroke patients who received PWI<12h of stroke onset was retrospectively studied (N=144) to determine whether the extent of correlation of PWI maps with neurologic deficits depends on deconvolution algorithm. Lesion volumes on perfusion maps calculated using truncated standard singular value decompositions (sSVD) was compared with PWI maps generated using a delay-insensitive technique (oSVD). oSVD was found to produce maps that correlated better with acute and follow-up neurological deficits than sSVD. oSVD produced maps that also better corresponded with follow-up lesion volumes in patients not given thrombolytic therapy.

                  1951.     Acute Middle Cerebral Artery Stroke - Comparison of Haemodynamic Timing Properties Assessed
                                 by Dynamic Contrast-Enhanced Perfusion Measurement and Arterial Spin Labeling

Johannes Gregori1, 2, Achim Gass1, 3

1Klinikum Mannheim, Universität Heidelberg, Mannheim, Germany; 2mediri GmbH, Heidelberg, Germany; 3Universitätsspital Basel, Basel, Switzerland

Dynamic Susceptibility Contrast (DSC) imaging and Arterial Spin Labeling (ASL) yield different basic timing properties – e. g. time to peak (TTP) in DSC and bolus arrival time (BAT) in ASL - which give different measures of the same underlying haemodynamic mechanisms. While the temporal resolution of DSC is limited to 1-2 seconds, ASL time series can in principle be acquired in arbitrarily small intervals.Reliable assessment of haemodynamics is crucial in acute stroke - especially penumbral areas are of major interest. In this work we present a comparison of BAT and TTP maps for cases of acute middle cerebral artery stroke. Focus is layd on arterial inflow delay differences on a sub-second scale which are difficult to assess by DSC imaging.

                  1952.     Does Arterial Spin Labeling Have a Role in Stroke Imaging? Preliminary Results from a 180 First Time
                                Stroke Patients Study

Esben Thade Petersen1, Amandine Cheze1, Violet Chua1, N V. Ramani1, Robert Ngo Gan1, Xavier Golay, 12

1National Neuroscience Institute, Singapore, Singapore; 2Singapore Bioimaging Consortium, Singapore, Singapore

Arterial Spin Labeling suffers from an inherently low signal-to-noise ratio which necessitates averaging and therefore relative long scan times, making the technique prone to motion artifacts. In addition, the white matter signal is at the sensitivity limit and it is often debatable whether ASL can contribute to stroke imaging at all. In this work, we compare information obtained with standard gadolinium-based perfusion methods to that obtainable using arterial spin labeling techniques. Comparable CBF and timing information was demonstrated with both techniques, while ASL delivered additional information on collateral perfusion which plays an important role in patients with cerebral artery occlusion.

                  1953.     Added Combined Value of Pulse Arterial Spin Labelling (PASL) and Susceptibility Weighted Imaging (SWI)
                                in Cerebral Vascular Occlusion, Stroke and Recovery

Magalie Viallon1, Andrea Federspiel2, Stephen Altrichter1, Aphrodite Syrogiannopoulou1, Roman Sztajzel1, Maria-Isabel Vargas1, Jacqueline Delavelle1, Karl Olof Lövblad1

1Hopital Universitaire de Genève, GENEVA, Switzerland; 2University Hospital of Psychiatry, BERN, Switzerland

Improving diagnosis, prognosis and management patient with cerebral vascular diseases means determining degree of tissue injury, location of occlusion and ischemic lesions, presence or not of micro-hemorrhages, of collateral luxury perfusion or not, etc. We believe that advanced new technique like ASL and SWI can bring new determinant informations to hightligh the hemodynamic compromise and improve patient management, with ASL being an helpful technique to follow reliably recovery. We try to address on 30 patients how ASL and SWI added to a clinical stroke protocol could lead to improved diagnosis, prognosis and patient management.

                  1954.     Which Physiological Parameters Determine Outcome in the Acute and the Subacute Phases of Acute
                                 Ischemic Stroke?

Kristjana Yr Jonsdottir1, Leif Ostergaard1, Kim Mouridsen1

1Aarhus University Hospital, Aarhus, Denmark

Patients presenting with acute ischemic stroke within 3 hours of symptom onset are routinely treated with rt-PA. However, chronic tissue damage may not be avoided by acute recanalization alone. We use predictive algorithms to characterize the temporal evolution of infarct risk in acute stroke, and assess the extent to which perfusion and diffusion MRI parameters predict subsequent infarct. Perfusion parameters are primarily dominant for the risk of tissue damage in acute phases, while diffusion determines final outcome in sub-acute phases. We speculate that predictive algorithms may elucidate the diagnostic significance of imaging findings at various time intervals after stroke onset.

                  1955.     Clinical Utility of Parametric Perfusion Estimates in Prediction of Final Outcome in Acute Stroke

Kim Mouridsen1, Kristjana Yr Jonsdottir1, Sune Jespersen1, Leif Ostergaard1

1Aarhus University Hospital, Aarhus, Denmark

DSC-MRI parameters such as cerebral blood flow (CBF) and mean transit time (MTT) are important diagnostic maps, e.g. in acute stroke where they are used to identify ischemic regions. These parameters are commonly estimated using standard SVD (sSVD) or block-circulant SVD (oSVD). Recently, a parametric Bayesian approach based on a physiological model of the microvasculature has been suggested which additionally allows computation of oxygen extraction fraction (OEF). Here we use voxel-wise predictive algorithms to demonstrate that the parametric model leads to significantly improved prediction of final infarct size. Moreover, the highest performance is observed by inclusion of the OEF.

                  1956.     DSC-MRI Errors Due to Bolus Delay and Dispersion in Sub Acute Stroke Patients: Implications for
                                Extending the Therapeutic Time Window

Lisa Willats1, Alan Connelly1, 2, Henry Ma, 23, Geoffrey Donnan2, 3, Fernando Calamante1, 2

1Brain Research Institute, Melbourne, Australia; 2University of Melbourne, Melbourne, Australia; 3National Stroke Research Institute, Melbourne, Australia

DSC-MRI perfusion measurements in stroke patients with cerebrovascular abnormalities are often erroneous because of bolus delay/dispersion.  Treatment of ischaemic stroke patients using thrombolytic agents such as tissue-type plasminogen activator (tPA) is currently restricted to a logistically demanding time window of less than 3 hours from symptom onset. Extension of this time window in individual patients requires reliable perfusion information. We show that the presence of dispersion causes an overestimation of the perfusion abnormality using standard and delay insensitive deconvolution analyses in a group of sub acute patients, and present a methodology to minimise dispersion errors in the affected patients.

                  1957.     Predicting Infarct Growth with Multi-Parametric Modeling in Acute Ischemic Stroke

Michael S. Bristow1, Brett W. Poulin1, Jessica E. Simon1, Michael D. Hill1, Jayme C. Kosior2, 3, Shelagh B. Coutts1, 4, Richard Frayne, 13, J Ross Mitchell, 13, Andrew M. Demchuk1, 4

1University of Calgary, Calgary, Canada; 2Schulich School of Engineering, Calgary, Canada; 3Seaman Family MR Research Centre, Calgary, Canada; 4Hotchkiss Brain Institute, Calgary, Canada

The purpose of this study was to determine if different multi-parametric models optimally distinguish infarct growth from each of the physiologically distinct core infarct and region of benign oligemia in acute ischemic stroke. We used logistic regression analysis to build models using diffusion- and perfusion-weighted MR imaging parameters that differentiate among these regions in 13 acute ischemic stroke patients. Interaction among MR parameters was also tested. We found that indeed different parameters, and consequently different models, optimally distinguish infarct growth from core infarct as compared to those that optimally distinguish infarct growth from benign oligemia.

                  1958.     Semi-Automated Topographical Scoring for MR Imaging of Ischemic Stroke

Robert Karl Kosior1, 2, Nikolai Steffenhagen2, Jayme Cameron Kosior1, 2, Andrew M. Demchuk2, 3, Richard Frayne2, 3

1University of Calgary, Calgary, Canada; 2Foothills Med Ctr, Calgary Health Region, Calgary, Canada; 3Hotchkiss Brain Institute, University of Calgary, Calgary, Canada

The Alberta Stroke Program Early CT Score (ASPECTS) is a topographical stroke scoring system based on the regional occupancy of identifiable brain infarct lesions on CT images. Infarct can also be detected by MR diffusion-weighted imaging (DWI). ASPECTS may be extended to MR and such an approach may have advantages over CT. We assessed ASPECTS-based MR topographical scoring (auto-MR-TS) using a digital brain atlas for 30 ischemic stroke patients. There were small but significant differences between auto-MR-TS and ASPECTS. Auto-MR-TS is objective and reproducible and may provide greater accuracy through greater lesion sensitivity.

                  1959.     Can Diffusion Tensor Imaging Detect the Degree of Neuronal Cell Membrane Damage in Stroke Patients? :
                                A Patient Study

Koji Sakai1, 2, Kei Yamada3, Susum Mori2, Tsunehiko Nishimura3

1Kyoto University, Kyoto, Japan; 2Johns Hopkins University, USA; 3Kyoto Prefectural University of Medicine, Japan

We attempted to further extend our hypothesis to real life brain infarctions involving the tightly packed white matter bundle. We performed retrospective measurements of diffusion tensor coefficients on patient with hyperacute/acute stage infarction involving posterior limb of internal capsule. From the results, we will consider the changes of diffusion tensor coefficients as the function and structure changing discriminants in hyperacute/acute brain infarction at different stage.

                  1960.     Elevations of Diffusion Anisotropy Are Associated with Hyper-Acute Stroke: A Serial Imaging Study

Yusuf A. Bhagat1, Muhammad S. Hussain1, Robert W. Stobbe1, Kenneth S. Butcher1, Derek J. Emery1, Ashfaq Shuaib1, Muzzafar M. Siddiqui1, Perkash Maheshwari1, Fawaz Al-Hussain1, Christian Beaulieu1

1University of Alberta, Edmonton, Canada

DTI studies of human ischemic stroke ≤24 hours of symptom onset have reported variable findings of changes in diffusion anisotropy. To address these heterogeneous results, we characterized longitudinal changes of fractional anisotropy (FA) by analyzing discrete ischemic deep and subcortical white matter, and deep and cortical gray matter regions during the hyperacute (2.5-7h) and acute (21.5-29h) phases of stroke onset in 13 patients. Overall, 9/13 patients scanned ≤7h showed elevated FA in at least one of the four tissues, and within the same cohort, 11/13 patients showed reduced FA in one of the four tissues 21.5-29h after stroke.

                  1961.     Comparing Mean and Directional Diffusivity in Human Ischemic Stroke

Chin-I Chen1, 2, Tammie L.S. Benzinger2, Peng Sun2, Tzy-Haw Wu, 23, Agus Priatna4, Chung-Yi Hsu5, Sheng-Kwei Song2

1Taipei Medical University - Wanfang Municipal Hospital, Taipei, Taiwan; 2Washington University, School of Medicine, St Louis, Missouri, USA; 3National Taiwan University Hospital, Taipei, Taiwan; 4Siemens Medical Solutions, USA, Inc, USA; 5Graduate Institute of Neuroscience, Taipei Medical University, Taipei, Taiwan

We present a study which compared DWI and DTI study in ischemic stroke with four different parameters: apparent diffusion coefficient (ADC), scaled relative anisotropy (sRA), axial diffusivity (AD) and the radial diffusivity (RD). We found the ADC and AD are significantly decreased in acute/subacute cases. RA and RD show the same trend but not statistically significant. In conclusion, axial diffusivity is comparable to ADC. DTI could potentially provide a quantitative biomarker to evaluate the ischemic stroke and predict outcome.

                  1962.     Neural Predictors of Immediate and Delayed Intense Naming Training Success in Chronic Aphasia

Harald Kugel1, Ricarda Menke1, Michael Deppe1, Annette Baumgaertner2, Hagen Schiffbauer1, Marion Thomas1, Kira Kramer1, Hubertus Lohmann1, Walter Heindel1, Stefan Knecht1, Caterina Breitenstein1

1University of Muenster, Muenster, Germany; 2Univerity Medical Center Hamburg-Eppendorf, Hamburg, Germany

Intense training facilitates the reacquisition of language in the chronic stage after stroke. We investigated with functional MRI, which brain regions are involved in immediate versus long-term success of intense naming training in patients with single left hemisphere strokes involving both Broca's and Wernicke's areas. All patients significantly improved after training. Short-term training success was predicted by increased activity in hippocampi, (pre)motor and attention areas, and right occipital lobe. Long-term training success, however, was predicted by increased activity in the left superior temporal lobe perilesionally to Wernicke's area and in the right-sided Wernicke's homologue.

                  1963.     Cerebrovascular Reserve Impairment is Associated with Recurrent Events in Patients with Carotid
                                Artery Occlusion

Stephen Goode1, Sunil Munshi2, Shane MacSweeney2, Dorothee Auer2

1Nottingham University Hospitals (NUH), Nottingham, UK; 2NUH, UK

Cerebrovascular reserve (CVR) measurements have been shown to be useful in predicting haemodynamic impairment and risk of future ischaemic events in patients with carotid artery disease. The aim of this study was to investigate the CVR of patients with carotid artery occlusion in relation to the presence of recurrent symptoms using hypercapnia fMRI. 13 patients with symptomatic carotid artery occlusion were scanned(1.5T). The degree of side-to-side asymmetry in the brain was calculated using the Asymmetry Index for all patients. In patients with recurrent symptomatic episodes we found a significantly increased asymmetry with ~18% ipsilateral reduced CVR.

                  1964.     Q-Ball MR Imaging of Longitudinal Brain Rewiring During Functional Recovery After Ischemic Stroke

Cristina Granziera1, Thomas Benner2, Dave Tuch2, Aneesh Singhal3, Walter Koroshetz3, Gunnar Krueger, Gregory Alma Sorensen2

1CHUV, Lausanne, Switzerland; 2Martinos Center-MGH-Harvard medical school, Charlestown, Massachusetts, USA; 3MGH, Boston, Massachusetts, USA

Investigating connectivity changes underlying post-stroke recovery is a challenging research’s field, with a potential future impact in treatment options and rehabilitation. We applied Q-ball MRI to monitor white matter plasticity in patients recovering from small MCA strokes. Our results showed a decrease in fiber trajectories at 1 month after stroke followed by a relative increase at 6 months in functional tracts involved in patients’ symptoms. This phenomenon could be due to masking/unmasking of the dominant ODF (edema, cellular/connectivity necrosis or damage) or to initial axonal degeneration followed by regenerative phenomena. Q-ball MRI appears a valuable method to  establish new therapeutic targets in stroke rehabilitation. Larger cohort studies are needed to confirm these preliminary findings.

 

Clinical Imaging with DTI & fMRI

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  1965.     Diffusion Tensor Peripheral Nerve Tractography ~ Histological Changes and Diffusion Anisotropy ~
 [Not Available]

Takehiko Takagi1, 2, Masaya Nakamura1, Masayuki Yamada2, Keigo Hikishima3, Suketaka Momoshima1, Kanehiro Fujiyoshi1, Hirotaka James Okano1, Yoshiaki Toyama1, Hideyuki Okano1

1Keio University School of Medicine, Shinjuku-ku, Japan; 2Fujita Health University School of Health Sciences, Toyoake, Japan; 3Keio University Center of Integrated Medical Research, Shinjuku-ku, Japan

We tried to determine whether noninvasive diffusion tensor tractography (DTT) could be used to track the peripheral nerve and whether recovery from contusion would show up as in ability to track fibers distal to the lesion site, correlating with histological and functional recovery. Diffusion tensor MRI data and fiber tracking were analyzed for peripheral nerve injury. We also measured fractional anisotropy (FA) values, histological and functional parameters. FA values reflected histological and functional changes, demonstrating the possible contribution of DTT to the evaluation of the some clinical events for peripheral nerve degeneration and regeneration.

                  1966.     Functional MRI Detection of Acute and Chronic Brain Plasticity Following Median and Ulnar Nerve
                               Transection Using Direct Nerve Stimulation at 9.4T

Rupeng Li1, Seth R. Jones1, Christopher Pawela1, Daniel Lee Shefchik1, Ji-Geng Yan1, Safwan S. Jaradeh1, Hani S. Matloub1, James S. Hyde1

1Medical College of Wisconsin, Milwaukee, USA

This study has four novel aspects. First, it showed, pure motor nerve activation in the rat central nervous system can be demonstrated using fMRI. Second, it proved that the motor nerve is less sensitive to injury than the sensory nerve. Third, it showed that inter-hemispheric brain plasticity occurs in the motor and sensory areas even if more than one nerve of the brachial plexus is intact. Finally, the thalamus and caudate putamen were activated in different ways in acute and chronic brain plasticity, which suggests that they may also play an important role in brain reorganization.

                  1967.     Cerebral White Matter Changes in Chronic Kidney Disease Patients Using DTI

Jiachen Zhuo1, Jiazheng Wang1, 2, Stephen Seliger1, David Lefkowitz1, Joshua Betz, 12, Shari Waldstein2, Leslie Katzel, 3, Steven Roys1, Rao Gullapalli1

1University of Maryland School of Medicine, Baltimore, Maryland, USA; 2University of Maryland Baltimore County, Baltimore, Maryland, USA; 3Baltimore Veterans Affairs Medical Center, Baltimore, Maryland, USA

Large prevalence of cerebral atherosclerosis and brain infarcts has been described in chronic kidney disease(CKD) patients. On 27 CKD patients, we used whole-brain/regional analysis and voxel-based-morphometry of DTI data to examine their brain white-matter(WM) changes. Both ADC and FA values were altered globally and regionally in CKD patients, reflecting disruption of WM microstructure. Among patients, higher GFR correlated with lower ADC and higher FA within the corpus-callosum. Regional microstructural changes were also more pronounced among diabetic compared to non-diabetic CKD patients. Our results indicate that DTI is able to differentiate morphological changes corresponding to functional changes in CKD patients.

                  1968.     Validation of Diffusion Tensor Imaging Tractography of Language Tracts with Intraoperative
                                 Subcortical Stimulations

Delphine Leclercq1, Hugues Duffau, Laurent Capelle, Christine Delmaire, Peggy Gatignol, Mathieu Ducros, Stephane Lehericy2

1Hopital Pitie-Salpetriere, Paris, France; 2Hopital Pitie Salpetriere, Paris, France

In this study, we used intraoperative subcortical electrical stimulations was to validate diffusion tensor imaging (DTI) tractography of language fiber tracts. Positive stimulation mapping was concordant with DTI fiber bundles in 81% of the stimulations. Stimulations of the different fasciculi induced variable language disorders that were specific of each fiber tract.

                  1969.     Optic Radiation Impairment in Friedreich Ataxia: A Diffusion-Weighted Imaging and Neurophysiological
                                 Study

David Neil Manners1, Giovanni Rizzo1, Filippo Fortuna1, Valerio Carelli1, Maria Lucia Valentino1, Emil Malucelli1, Caterina Tonon1, Rocco Liguori1, Bruno Barbiroli1, Raffaele Lodi1

1Università di Bologna, Bologna, Italy

Optic impairment is common in mitochondrial disorders. Its occurrence in Friedreich Ataxia (FRDA) has been recognized for a long time, but poorly characterized. Diffusion weighted imaging (DWI), which can disclose increased water apparent diffusion coefficient (ADC) in brain areas where axonal loss occurs, and visual evoked potentials (VEPs) were used to look for evidence of optic radiation involvement in FRDA patients. We provide evidence that microstructural damage of the optic radiations in FRDA patients contributes to clinical and neurophysiological visual involvement in this disease.

                  1970.     Greater Attentional Modulation in HIV Patients: A One-Year Follow-Up Study

Linda Chang1, Renat Yakupov1, Grace Crocket1, Mary Ricardo-Dukelow1, Helenna Nakama1, Michael Watters1, Thomas Ernst1

1John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, USA

HIV-infection can lead to decreased attention, which may be further exacerbated with aging.  Functional MRI was performed in 46 HIV-subjects and 32 seronegative-controls during three visual attention tasks at baseline and one-year.  Over one-year, these clinically stable HIV-patients showed increased BOLD signals in the load regions of the attention network for all tasks, while controls showed decreased activation in the attention network for one task.  These findings suggest that HIV patients required increased usage of reserve regions to maintain performance with aging after only one year.  Further longitudinal follow-up will determine whether this reserve capacity will exhaust with further aging.

                  1971.     Diffusion-Weighted Imaging and Magnetization Transfer Imaging of Tardive and Edentulous Orodyskinesia

Yvan Boulanger1, Abdesslem Khiat1, Yevgeniy Kuznetsov1, Pierre J. Blanchet2

1CHUM, Montreal, Canada; 2Université de Montréal, Montreal, Canada

The possibility of using diffusion-weighted imaging (DWI) and magnetization transfer imaging (MTI) parameters as markers of dyskinesia was investigated by comparing data for four groups of subjects: drug-treated patients with tardive dyskinesia (TD), edentulous orodyskinesia patients (EOD), drug-treated patients without TD and control subjects. Apparent diffusion coefficients (ADC) were increased in the basal ganglia in drug-treated patients with TD relative to those without TD and to control subjects as well as in EOD patients relative to control subjects. Magnetization transfer ratios (MTR) were also increased in EOD patients relative to control subjects but ADC values offered the best discrimination potential.

                  1972.     Normalization of FMRI Activation Patterns in HIV Positive Individuals with Cognitive Impairment After
                                Treatment with Lithium

Giovanni Schifitto1, Michelle D. Gaugh1, Madalina Tivarus1, Tong Zhu1, Kim Cruttenden1, David Gill2, Jianhui Zhong, 13, Harris A. Gelbard1

1University of Rochester, Rochester, New York, USA; 2Pennsylvania State University, Hershey, Pennsylvania, USA; 3University of  Rochester, Rochester, New York, USA

HIV positive patients with cognitive impairment were enrolled in a ten-week clinical trial of lithium 300mg BID, and administered an FMRI working memory task at baseline and week 10. A group of HIV positive patients without impaired cognitive functioning were administered the same task at a single time point. Results indicate that activation patterns in post-treatment lithium patients more closely resemble patterns of HIV patients without impairment than activation patterns in lithium patients before treatment, and suggest that lithium may normalize brain activation during a working memory task in HIV patients with cognitive impairment. 

                  1973.     The Brain's FMRI Response to Heat-Pain Stimulation in Diabetic Neuropathy

Iain D. Wilkinson1, Rajiv A. Gandhi2, Michael D. Hunter1, Dinesh Selvarajah2, Celia J. Emery2, Paul D. Griffiths1, Solomon Tesfaye2

1University of Sheffield, Sheffield, UK; 2Royal Hallamshire Hospital, Sheffield, UK

Abnormal pain perception is common in Diabetic Neuropathy (DN). This work investigates the brain’s response to pain stimulation in patients with Diabetes Mellitus using BOLD fMRI. Twenty-three males took part: 5 without diabetes, 6 with diabetes without DN; 6 with diabetes with painful DN and 6 with diabetes with painless DN. Heat-pain stimulation was provided by a peltier-type device during BOLD-fMRI. Brain response was compared using SPM. Analysis indicates differences in the brain’s haemodynamic response to heat-pain between subject groups at different stages of DN with a negative correlation between composite neuropathy score and BOLD response within the thalamus.

                 1974.     Differentiating Pain-Intensity from Stimulus Encoding in Brain Activation in Neuropathic Pain

lino Becerra1, 2, Gautam Pendse1, david Borsook1, 2

1McLean Hospital, Belmont, Massachusetts, USA; 2Massachusetts General Hospital, Boston, Massachusetts, USA

We studied neuropathic pain patients with pain to one side of the face.  We sought to determine brain structures that encoded pain intensity regardless of stimulated side; brain substrates that encoded sensation regardless of the perception of the stimulus (painful or not); and brain structures whose activation significantly differed between the affected and unaffected side but that do not encode pain intensity.  Thermal (heat and cold) and mechanical (brush) stimuli were used to evoke pain.

                  1975.     fMRI in Patients with Lumbar Radiculopathy

Harish Sharma1, Raj Gupta2, Bill Olivero3

1University of Illinois at Urbana-Champaign, Urbana, Illinois, USA; 2UIC college of Medicine at Urbana-Champaign, USA; 3Carle Hospital, USA

fMRI is used as a tool to study how brain processes pain. Most of the studies done are fMRI with artificially induced pain on normal subjects. In the current study we have tried to use fMRI in understanding where and how chronic pain is processed in the brain. Our analysis showed activations in the pain centers of the brain when the patient experienced pain while no activation was observed when the patient experienced no pain.

                  1976.     Visual Cortex Reorganization Among Early and Late Blind for Tactile Object Recognition

Anand Mohan Sinha1, Senthil S. Kumaran1, Rohit Saxena1, Uma Sarma1

1All India Institute of Medical Sciences, New Delhi, India

Using BOLD fMRI technique, we investigated the differences between early and late blind subjects on tactile object recognition task. We observed early blind predominantly recruiting temporal-frontal whereas late blind subjects had significant parietal-frontal activation. This contrasting activation pattern suggests adaptive changes in brain with input of visual stimuli.

 

Normal Human Brain: Connections & Activations

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                   2036.     Pre-Attentive Processing of Contour Deviance in Musicians

Benedikt Habermeyer1, Marcus Herdener, Fabrizio Esposito, Caroline C. Hilti, Markus Klarhoefer, Francesco di Salle, Klaus Scheffler, Katja Cattapan-Ludewig, Erich Seifritz

1University of Basel, Basel, Switzerland

Impact of musical expertise on functional capabilities of frontal brain regions remains elusive. We used fMRI to investigated differential BOLD responses between musicians and non-musicians. Musicians showed a different activation pattern with an activation in the right ventromedial prefrontal cortex, bilateral inferior frontal gyrus and left superior temporal gyrus. BOLD signal showed a significant correlation to behaviourally tested ability to discriminate changes in sound patterns. Our data shows that prefrontal cortex is engaged in melody processing. Activation in the ventromedial prefrontal cortex supports the hypothesis that this area is a node that is important for binding music with memories within an broader melody-responsive network.

                  2037.     Alcohol-Induced Changes in the Hemodynamic Response Function in Event-Related FMRI :
                                 Evidence for Slow Down of Neurovascular Coupling

Michael Luchtmann1, Tobias Moench1, Maurice Hollmann1, Katja Jachau1, Sandra Boettcher1, Johannes Bernarding1

1Otto-von-Guericke University of Magdeburg, Magdeburg, Germany

The influence of ethanol on human neurophysiology was examined by methods of functional neuroimaging. The individual hemodynamic response functions (HRF) of 15 volunteers were observed within four different brain areas (left and right motor cortex, supplementary motor area (SMA), visual cortex) for changes caused by acute alcohol intoxication. With a mean blood alcohol concentration of 0.82 ‰ all subjects showed clear changes in shape of HRF, whereby most significant alteration was observed in SMA. The presented results may be a hint for the known effect of alcohol to impair initiation of complex motor actions.

                  2038.     Heart-Brain Interaction: An FMRI Study of the Human Brain Response to the Cold Pressor Test

Raphael Delano Hazel1, Deepu Alexander1, Edwin Estrada1, Marguerite Roth1, William Schapiro1, Mark Wagshul2, Nathaniel Reichek1

1St Francis Hospital, Roslyn, New York, USA; 2Stony Brook University, Stony Brook, New York, USA

The goal of this study was to establish the extent and characteristics of the heart-brain interaction through the neurogenic response to the CPT using fMRI. Activity was observed in the insular cortex in all subjects, but activity in the region of the brainstem involving the NTS was recorded in only two subject during the 60s CPT. Early observations suggest a progressive brain response to the cold  stress.

                  2039.     Compensatory Recruitment After 36 H Total Sleep Deprivation and the Relationship with Executive Control

Yong-cong Shao1, Bo Wen2, En-mao Ye1, Jian-lin Qi1, Guo-hua Bi1, Dan-Min Miao3, Lin Ma2, Zheng Yang1

1Beijing Institute of Basic Medical Sciences, Beijing, People's Republic of China; 2General Hospital of People's Liberation Army of China, Beijing, People's Republic of China; 3the Forth Military Medical University, Xi'an, People's Republic of China

Executive function relying on inhibition is affected by total sleep deprivation (TSD). In this study, we investigated the influence of TSD on response inhibition using combined behavioral, fMRI techniques and a visual Go/No-go task. Results indicated that sleep deprivation lowered Go/No-go sustained, task-related activation of ACC regions. The significant activation of prefrontal lobe had shown a along with the decline performance, more attention resources were needed to perform the Go/No-go task after TSD. These results suggested that TSD were accompanied with an impact on brain functions of response inhibition and required more anticipation of prefrontal lobe for compensatory recruitment.

                 2040.     Increased Change in Water Dffusion MRI Following Low Frequency Repetitive Transcranial Magnetic
                               Stimulation

Mitsunari Abe1, Tatsuya Mima1, Nobukatsu Sawamoto, Shin-ichi Urayama1, Toshihiko Aso2, Denis Le Bihan2, Hidenao Fukuyama1

1Human Brain Research Center, Kyoto Grad. Sch. Med., Kyoto, Japan; 2NeuroSpin, France

Low frequency repetitive transcranial magnetic stimulation (rTMS) was performed within a 3T MRI scanner while diffusion-weighted MR images were collected, before and after the stimulation. Following the rTMS, water diffusion was significantly increased in bilateral motor-related areas. The water diffusion increase in the stimulated primary motor cortex was recovered within 10 min while that of some remote areas in contralateral hemisphere remained for 10-20 min. These findings support that rTMS conditioning effects (cortical inhibition) induce transient structural changes in extended motor network systems.

                  2041.     Effects of Directional Resolution in Diffusion Tensor Tractography: Comparisons on Total Fiber Volume
                                and Fiber Consistency

Yen-Wei Cheng1, Ming-Chung Chou1, Hsiao-Wen Chung1, Cheng-Yu Chen2, Yi-Jui Liu3

1National Taiwan University, Taipei, Taiwan; 2Tri-Service General Hospital, Taipei, Taiwan; 3Feng Chia University, Taichung, Taiwan

To keep the scan time almost the same, DTI data were acquired separately using direction resolution of 6, 15 and 32 at NEX of 5, 2 and 1 .We found that 32 directional DTI had the largest traced fiber volume and highest fiber consistency. It suggests the directional resolution is more important than image SNR in terms of traced fiber volume and fiber consistency. Our results showed that the increase of diffusion directions in DTI not only impacts the precision and accuracy of in vivo fractional anisotropy, mean diffusivity, and principal eigenvector, but also improves the diffusion tensor tractography results.

                  2042.     Reproducibility of Fractional Anisotropy and Mean Diffusivity in Diffusion Tensor Imaging at 3.0 T

Yundi Shi1, Sarang Joshi1, James N. Lee1, William R. Marchand, 12, Esther Rashkin1, Edward W. Hsu1

1University of Utah, Salt Lake City, Utah, USA; 2Department of Veterans Affairs, VISN 19 MIRECC, Salt Lake City, Utah, USA

DTI has been widely used in brain study, which made reproducibility of the measurements essential in order to perform comparison neuroimaging techniques. This abstract described our recent study using Fisher-Pitman permutation test to compare two DTI datasets acquired at 3.0T, different scan time with the same protocol voxel-by-voxel, with the goal to evaluate statistically the significant difference between scans as well as locate the voxels with detectable difference. Results reveal that DTI measurements including FA and mean diffusivity are highly reproducible. Furthermore, the significant different voxels were found to be mostly at the brain periphery, which could be caused by imperfect registration or partial volume effects.

                  2043.     Grey Matter Changes and Motor Learning of Meaningful and Meaningless Actions: A Tensor-Based
                                Morphometry Study

Elisabetta Pagani1, Antonia Ceccarelli1, Maria A. Rocca1, Roberto Gatti1, Andrea Falini1, Massimo Filippi1

1Scientific Institute and University Ospedale San Raffaele, Milan, Italy

Cross-sectional voxel based morphometry studies have demonstrated learning-dependent changes in the adult human brain. We performed tensor based morphometry (TBM) on 3D T1-weighted fast field echo images in 22 healthy subjects at three different time points: 1) before motor training; 2) at the end of two weeks of training and, 3) three months later. During motor training, 11 subjects learned meaningful (MF) actions, and the other 11 meaningless (ML) actions. We demonstrated that learning of MF and ML actions might result in structural GM changes in different brain areas which are part of specific neuronal networks.

 

Drugs & the Developing Brain

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  2082.     Retinal Folding in the Term Rabbit Fetus - Developmental Abnormality or Fixation Artefact?

Jane Halliday1, Julian French1, Marietta Scott1, Carsten Liess1, John Waterton1, Jane Stewart1

1AstraZeneca, Macclesfield, UK

Prior to administration of candidate medicines to women of child bearing potential, studies must be performed in pregnant animals to assess detrimental effects, such as malformations in embryofetal development.  One such effect is “slight retinal folding” in the rabbit fetus. However, there is evidence that these folds may be caused by the traditional fixation process used in their examination.  This study used MRI to assess rabbit retinal architecture both pre- and post-fixation.  Whilst no retinal folding was detected in fresh specimens, folds were observed in 79% of fetuses post-fixation, inferring that retinal folds in the rabbit fetus are commonly artefactual.

                  2083.     Effect of Fluoxetine on the Developing Brain

Willy Gsell1, Estelle Jamard2, Francois Dauphin2, Michel Boulouard2, Jan Booij3, Amy Herlihy1, Sharon Williams1, Liesbeth Reneman3

1Hammersmith Hospital, Imperial College London, London, UK; 2University of Caen, Caen, France; 3Academic Medical Centre, Amsterdam, Netherlands

Fluoxetine (a serotonin reuptake inhibitor) has recently been approved for use in children and adolescents based on clinical trials performed in adults. However, there are concerns on the safety of fluoxetine when administered to children and adolescents. In this study we conducted a pre-clinical assessment to determine if the effects of the fluoxetine on the serotonin system are dependent on age, with respect to behaviour, density of serotonin transporters, and brain activation.

                  2084.     Regional Brain Alterations in Children with Prenatal Alcohol Exposure: A Preliminary 3D Multi-Voxel 31P
                                Spectroscopy Study at 4 Tesla

Jeffrey A. Stanley1, Lisa M. Chiodo1, Dalal Khatib1, Rachel M. Dick1, Jalpa Patel1, Virginia Delaney-Black1, John H. Hannigan1

1Wayne State University School of Medicine, Detroit, Michigan, USA

Maternal alcohol consumption during pregnancy can harm the fetus, particularly the vulnerable central nervous system, making prenatal alcohol exposure (PAE) a leading cause of mental retardation and developmental disorders that include deficits in behavior and cognition (focused attention, arithmetic and working memory).  Young children with and without PAE were assessed in 4 key regions using 3D multi-voxel 31P spectroscopy; a method sensitive to critical neurodevelopmental changes.  Results show regional alterations in membrane phospholipid and high-energy phosphate metabolism. This suggests that maternal alcohol consumption during pregnancy may alter the time course of developmental changes from that seen in healthy children.

                  2085.     Diffusion Tensor Tractography of Children with Fetal Alcohol Spectrum Disorder

Catherine Lebel1, Carmen Rasmussen1, Katy Wyper1, Gail Andrew2, Jerome Yager1, Christian Beaulieu1

1University of Alberta, Edmonton, Canada; 2Glenrose Hospital, Edmonton, Canada

The purpose of this study was to determine the range of white matter abnormalities in children with fetal alcohol spectrum disorder (FASD) using diffusion tensor imaging (DTI). 24 children with FASD and 95 controls 5-13 years underwent DTI scans. Tractography delineated ten white matter tracts in each individual and measure fractional anisotropy and mean diffusivity. Significant diffusion abnormalities were observed in the splenium and genu of the corpus callosum, superior and inferior longitudinal fasciculi, inferior fronto-occipital fasciculus and cingulum. This supports previous findings of callosal abnormalities in FASD and demonstrates diffusion changes beyond the corpus callosum for the first time.

                  2086.     Increased Creatine and Choline in the Brains of Children Exposed to Methamphetamine Prenatall

Linda Chang1, Christine Cloak1, Bradley Tokeshi1, Brooke Hedemark1, Caroline Jiang1, Sarah Farhnam1, Lynne Smith2, Thomas Ernst1

1John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, USA; 2Harbor-UCLA Medical Center, Torrance, USA

Methamphetamine (METH) is a neurotoxic drug but its effects on brain development has not been well studied.  Proton MRS was performed in seventy 3-4 year old children (33 METH-exposed prenatally and 37 un-exposed controls).  Despite similar physical characteristics (including head circumference), global cognitive function (on Stanford-Binet), parental education, intelligence and mood, METH-exposed children had higher total creatine and choline concentration than un-exposed controls.  Since total creatine and choline are higher in glia than neurons, these findings suggest abnormalities in glia development in these children with prenatal METH-exposure.

                 2087.     MRI Evaluation of Morphological Changes Following Soman Exposure and Galantamine Treatment

Jiachen Zhuo1, Jiazheng Wang2, Eduardo Helal-Neto3, Yasco Aracava3, George Makris1, Edna F.R. Pereira3, Rao P. Gullapalli1, Edson X. Albuquerque3

1University of Maryland School of Medicine, Baltimore, Maryland, USA; 2University of Maryland Baltimore County, Catonsville, Maryland, USA; 3University of Maryland Baltimore, Baltimore, Maryland, USA

The acute toxicity of nerve agents such as soman, sarin, tabun and VX has been associated with their potency to irreversibly inhibit acetylcholinesterase.  In this study we examine the brain morphological changes following lethal exposure of soman in a guinea pig model.  Further we assess the therapeutic effects of galantamine that blocks the effectiveness of the nerve agent.  Our study reveals that both male and female guinea pigs undergo morphological changes immediately following soman exposure with large effects in the area of piriform, amygdalar and hippocampal areas with maximal damage at 24 hrs.  Further, the effect of galantamine is immediate  and is able to reverse this damage.

                  2088.     Neuroprotective Effects of Alpha Lipoic Acid on Ecstasy-Exposed Zebra Finches: An in and ex Vivo
                                Volumetric Analysis

Parastou Foroutan1, 2, Crystal P. Perreault1, Susanne L.T. Cappendijk1, Samuel Colles Grant1, 2

1The Florida State University, Tallahassee, Florida, USA; 2FAMU-FSU College of Engineering, Tallahassee, Florida, USA

Adolescent Ecstasy use is known to induce cognitive impairment later in life. There are indications that this impairment is due to free radical formation. MR Microscopy techniques at 21.1 T were used to study the effects of the antioxidant alpha lipoic acid on Ecstasy-exposed zebra finches. Multi-slice 2D fast spin-echo images were acquired both in and ex vivo. 3D gradient-recalled echo images (40-micron isotropic resolution) also were obtained from ex vivo brain samples, and a volumetric analysis was performed on all datasets. These techniques contribute to a better understanding of the pharmacological effects of Ecstasy on neuroanatomical pathways of cognition.

                  2089.     Identification of the Teratologic Effect of Prenatal Exposure of Cocaine Using Voxel Based Morphometry

Eric Yann Pierre1, Sonia Minnes1, Olivier Salvado2, Lynn Singer1, Paul Weishampel1, Daniel T. Boll3, Jean Adelaide Tkach1

1Case Western Reserve University, Cleveland, USA; 2CSIRO - e-Health Research Centre, Brisbane, Australia; 3Duke University, Durham, USA

Cocaine crosses the placental and fetal brain barriers and directly affects neurodevelopment. Prenatal Cocaine Exposure (PCE) has been correlated with deficits in cognitive and language functioning, visual-spatial and arithmetic skills. However, little is known about specific teratologic effects of PCE. We used high spatial resolution MRI of exposed and non cocaine-exposed children and  Voxel Based Morphometry to identify local  tissue volume differences between the two populations.  Local reductions in  white and  gray matter in regions of the visual association cortex involved in visual-spatial task performance were identified in PCE subjects

 

Diffusion Measures of Disease in MS

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  2117.     Diffusion Tensor Imaging in Pediatric Multiple Sclerosis: Studying Hemispheric White Matter

Allison Bethune1, Brenda Banwell1, 2, Conrad Rockel1, John Sled3, Donald Mabbott1, 2

1The Hospital for Sick Children, Toronto, Canada; 2University of Toronto, Toronto, Canada; 3Toronto Centre for Phenogenomics, Toronto, Canada

The goal of this study was to explore hemispheric white matter (WM) changes in pediatric onset multiple sclerosis using DTI. T1, PD/T2 and DTI images for sixteen affected children and sixteen healthy controls were compared. Robust significant differences in fractional anisotropy and apparent diffusivity were observed in children with MS relative to healthy controls, and suggest compromised WM integrity may occur early in MS pathology. Further knowledge of pediatric onset MS is valuable in understanding the impact of WM damage in developing neural tissue.

                  2118.     Diffusion Tensor Imaging in Multiple Sclerosis: Comparison of Radial and Axial Diffusivity Markers
                                 in Different Clinical Forms

Salem Hannoun1, Françoise Durand Dubief, 12, Danielle Ibarrola3, Christian Confavreux2, Dominique Sappey-Marinier1, 3

1CREATIS-LRMN, UMR5220 CNRS & U630 INSERM & Université de Lyon, Villeurbanne, France; 2Hôpital Neurologique, Groupement Hospitalier Est, Bron, France; 3CERMEP-Imagerie du vivant, Groupement Hospitalier Est, Bron, France

This work concerned a longitudinal study of MS patients being followed by DTI to provide new markers of pathological processes and to evaluate the progression rate of the disease. Diffusion coefficients such as axial and radial diffusivities (ë1, ë2) were compared to FA and ADC. Preliminary results obtained in 35 patients showed significant increase of ADC, ë1 and ë2 values in different brain regions such as corpus callosum, grey nuclei, and white and grey matter.  A larger change in ë2 suggested that radial diffusivity might be a better marker of myelin integrity whereas ë1 is more specific to axonal degeneration.

                  2119.     Diffusion Tensor Eigenvalues Demonstrate Inherent Differences Between MS Lesion Subtypes

Irene Vavasour1, Cornelia Laule1, Shannon Kolind1, David Li1, Anthony Traboulsee1, Alex MacKay1

1University of British Columbia, Vancouver, Canada

20 MS subjects were scanned with diffusion tensor imaging, and mean diffusivity, fractional anisotropy and the diffusion tensor eigenvalues were determined for enhancing lesions, isointense T1 lesions, hypointense T1 lesions and areas of contralateral NAWM. Diffusion metrics were significantly different between all lesion types and NAWM. The largest increase in eigenvalues was observed in hypointense T1 lesions (λ 1=36%, λ 2=74%, λ 3=131%), followed by enhancing lesions (λ 1=20%, λ 2=42%, λ 3=83%) and then isointense T1 lesions (λ 1=14%, λ 2=25%, λ 3=38%). The changes in mean diffusivity and especially FA were driven by the larger changes in smaller eigenvalues rather than the primary eigenvalue.

                  2120.     A Diffusion Tensor Imaging  Surrogate Marker of Brain Atrophy in Multiple Sclerosis

Khader M. Hasan1, Christopher Halphen1, Arash Kamali1, Jerry S. Wolinsky1, Ponnada A. Narayana1

1University of Texas Health Science Center at Houston, Houston, USA

In this report we used a recently described and validated diffusion tensor imaging method to obtain the brain parenchymal fraction as a surrogate of atrophy on a cohort of relapsing and remitting (RRMS) patients and healthy adult controls. We demonstrate the utility of this approach by demonstrating strong correlation with the expanded disability status score (EDSS) and disease duration (DD).

                  2121.     DTI Measures of Forniceal Injury Correlate with Episodic Memory Dysfunction in MS

Micheal Phillips1, Kenneth Sakaie1, Stephen Rao1, Janice Zimbelman1, Lael Stone2, Erik Beall2, Katerine Koenig2, Ruthann Marrie3, Jian Lin2, Mark Lowe2

1Cleveland Clinic, Cleveland , USA; 2Cleveland Clinic, Cleveland, USA; 3University of Manitoba, Winnipeg, Canada

Cognitive deficits affect as many as 50% of patients with MS with 30-40% of patients having specific deficits in episodic memory.  The hippocampus and fornix a clear role in episodic memory function.  DTI measures forniceal injury were compared to neuropsychological tests of episodic memory function in MS patients.  Axial diffusivity within the left hippocampus demonstrates an inverse correlation with verbal episodic memory dysfunction. Axial diffusivity within the right hippocampus demonstrates an inverse correlation with nonverbal memory dysfunction.  Finding suggests that DTI of the fornix may be a potential future noninvasive biomarker of episodic memory dysfunction in MS.

                  2122.     Diffusion Tensor Imaging of Multiple Sclerosis Cervical Spinal Cords

T. H. Kim1, L. Zollinger1, X. F. Shi1, J. Anderson1, J. Rose1, Eun-Kee Jeong1

1University of Utah, Salt Lake City, Utah, USA

Multiple sclerosis (MS) is a white-matter disease with various pathologic stages such as demyelination, remyelination, inflammation, and axonal damage. These stages change the microscopic physical environments of the tissue water. Diffusion tensor MRI (DTI) is sensitive to the physical change in the tissue and may be used to detect early changes in the course of the disease. To investigate cervical spinal cord (CSC) damage, DTI has been employed using a 3D multi-shot diffusion-weighted EPI (ms-DWEPI), necessitating the development of a quadrature rf-coil and a controlled experimental environment. From DTI images, we have attempted to demonstrate cervical spinal cord damage in white matter in radial and longitudinal views of the cord.

                  2123.     Temporal Changes of Fractional Anisotropy in DTI of the Corpus Callosum in Secondary Progressive
                                Multiple Sclerosis: A Putative Marker of Accumulating Tissue Damage
 [Not Available]

Weitian1, Jianhui Zhong1, Xiang Liu1, Praveen Rao2, Benjamin M. Segal2, Sven Ekholm1

1University of Rochester Medical Center, Rochester, New York, USA; 2University of  Michigan, Ann Arbor, Michigan, USA

Secondary progressive multiple sclerosis (SPMS) is characterized by gradually accumulating neurological disability while regular MR imaging findings including enhanced lesions on the postcontrast images are not sensitive and specific in predicting the prognoses. Diffusion tensor imaging (DTI) was suggested to be sensitive in detecting brain tissue damage in MS. A longitudinal DTI study, including 11 patients who completed 6 bimonthly MR scans in the period of one year and 5 matched controls, was performed. Patients were divided into enhancing and non-enhancing group based on the presence of T1 enhancing lesions during the one-year study period. The Fractional anisotropy (FA) and Mean Diffusivity (MD) values in genu, body and splenium of corpus callosum (CC) were measured and compared between groups by repeated measures analysis of variance(ANOVA). Our results showed a significant difference in the time course change of FA between groups. Enhancing group also showed significantly progressive FA decrease in body and splenium CC over time. Our results suggest that the temporal decrease in FA in corpus callosum may be used as a putative marker to predict the severity and activity of SPMS.

                  2124.     Geometric Distortion Correction on EPI: An Application for Diffusion Tensor Imaging of the Human
                                 Optic Nerve

Udomchai Techavipoo1, 2, Annette Okai1, Thomas Leist1, Alex Dresner2, John Lackey1, Jianrong Shi1, Song Lai1

1Thomas Jefferson University, Philadelphia, Pennsylvania, USA; 2Philips Medical Systems, Netherlands

A reliable and practical method based on PLACE and SPHERE for correction of field-inhomogeneity distortion on EPI was applied to diffusion tensor imaging (DTI) of the human optic nerve. A conventional DTI sequence was tailored practically to overcome difficulties such as the optic-nerve size, the confounding signals from surroundings, the persistent motions, and the geometric distortion caused by susceptibility-induced magnetic field inhomogeneity from bone cavities and sinuses around the optic nerve. Values of DTI parameters before and after geometric distortion correction were compared to observe the integrity of the DTI sequence and the distortion correction.

                  2125.     Visualisation and Quantitative Assessment of the NAWM in MS Patients by Using Q-Space Analysis of the
                                Slow Diffusion Component at 3T

Katrin Weier1, Eli Renate Gruener2, Jochen G. Hirsch1, Matthias Guenther3, Michael Amann1, Ludwig Kappos1, Wolfgang Steinbrich1, Ernst-Wilhelm Radue1, Achim Gass1

1University Hospital Basel, Basel, Switzerland; 2University of Bergen, Bergen, Norway; 3University Hospital Mannheim, Mannheim, Germany

Previous clinical studies have shown promising results of Q-space imaging of the slow diffusion component. It has been suggested, that the slow diffusion might predominantly represent intra-axonal/intra-cellular water diffusion. In order to investigate abnormality in the normal appearing white matter (NAWM) of MS patients we used an adapted protocol for clinical use of probability of zero displacement (PZD) on a 3T system. PZD maps were highly sensitive to detect reductions of the slow diffusion component in the NAWM of patients with different MS types. The resulting data allows a visual analysis to assess abnormality in the otherwise NAWM.

                  2126.     Resting State Sensorimotor Functional Connectivity in Multiple Sclerosis Correlates with Transcallosal
                                 Motor Pathway Transverse Diffusivity

Mark J. Lowe1, Erik B. Beall1, Ken E. Sakaie1, Katherine A. Koenig1, Lael Stone1, Ruth Ann Marrie2, Micheal D. Phillips1

1Cleveland Clinic, Cleveland, Ohio, USA; 2University of Manitoba, Winnipeg, Canada

We present initial results demonstrating, for the first time, a significant correlation between anatomic connectivity using DTI-based measures of white matter integrity and functional connectivity using spontaneous low frequency BOLD fluctuations. We report a signicant inverse correlation between transverse diffusivity of water averaged along the transcallosal motor pathway and functional connectivity between the primary sensorimotor regions in multiple sclerosis patients.

                  2127.     Towards Assessing White Matter Integrity in Patients with Relapsing-Remitting Multiple Sclerosis Treated
                                with Pioglitazone

Dinesh K. Shukla1, Claudia K. Kaiser1, Demetrios D. Skias1, Glenn T. Stebbins2, Douglas L. Feinstein1

1University of Illinois at Chicago, Chicago, Illinois, USA; 2Rush University Medical Center, Chicago, Illinois, USA

Pioglitazone is an FDA-approved agonist, which has shown to reduce clinical and histological symptoms in MS animal model. We carried out a phase-I clinical trial of Pioglitazone in RRMS patients to monitor longitudinal changes in the characteristics of intrinsic brain tissue properties. DTI data were acquired and the results suggest that DTI parameters are sensitive markers to study the MS disease progression and may be predictive of pathological changes. Pioglitazone may improve anisotropy and reduce mean diffusivity at the site of degenerating tissue in RRMS patients. Further testing of this drug in larger cohort of MS patients is therefore warranted.

                  2128.     Application of Locally Linear Embedding to Diffusion-Weighted MRI Data: Potential New Contrast Patterns
                                in Multiple Sclerosis

Peter Mannfolk1, Markus Nilsson1, Jimmy Lätt1, Elna-Marie Larsson1, Freddy Ståhlberg1, Ronnie Wirestam1, Sara Brockstedt1

1Lund University, Lund, Sweden

Several contrast parameters can be established by the use of diffusion weighted MRI, such as the apparent diffusion coefficient (ADC). These parameters are calculated from several samples of the diffusion signal attenuation. Although such contrast parameters can reveal differences between healthy and pathological tissue there exists a risk that different types of tissue are classified as similar even though they display differences in the signal versus b-curve. We investigate whether more information can be found in such data sets by use of Locally Linear Embedding. Analysis is performed on DW images acquired from one patient suffering from multiple sclerosis.

 

Brain Tumor:  Perfusion, Diffusion & Contrast Techniques

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  2190.     Validation of Neuroradiologic Response Assessment in Adult Glioblastoma: Cross-Comparison of
                                 Linear and  Volumetric Methods on Post-Contrast Standard Thick and High Resolution T1WI

Mei-Yun Wang1, Jing-Liang Cheng2, Wei-Ting Zhang1, Ming-Wang Zhu1, Craig Peterson1, Poe-Zhou Chen1, Heisoog Kim1, Prescilla Yeo1, Jie Bai2, Hui-Xia Zhang2, Yan Du2, A Gregory Sorensen1

1Massachusetts General Hospital, Charlestown, Massachusetts, USA; 2the First Affiliated Hospital of Zhengzhou University, Zhengzhou, People's Republic of China

The improvement of imaging technology and volume measurement software has made volumetric method become a more practical and promising end point for evaluating tumor response status in GBM. This study showed that volumetric method has more sensitivity and accuracy than linear  method in detecting tumor response in adult GBM, particularly volume on post-contrast high resolution T1WI; volume on post-contrast thick T1WI may be taken an alternative to volume on post-contrast high resolution T1WI when considering the advantage of less time-consuming in both image acquisition and volume measurement.

                  2191.     MRI for Evaluation of Brain Lesions: Intraindividual Comparison of Gadobenate Dimeglumine vs
                                 Conventional Gadolinium Contrast Agents

Howard A. Rowley1, Guiseppe Scialfa2, Pei-yi Gao3, Kenneth R. Maravilla4, Joseph A. Maldjian5, Matthew J. Kuhn6

1University of Wisconsin, Madison, Wisconsin, USA; 2Hospital Niguarda Ca'Granda, Milan, Italy; 3Beijing Tian Tan Hospital, Beijing, People's Republic of China; 4University of Washington, Seattle, Washington, USA; 5Wake Forest University, Winston-Salem, North Carolina, USA; 6Southern Illinois University, Springfield, Illinois, USA

The enhancement provided by a unique contrast agent with transient protein interaction (gadobenate dimeglumine) was compared with enhancement after other non-protein interacting gadolinium contrast agents in two large scale trials. The greater enhancement seen after gadobenate dimeglumine at a dose of 0.1 mmol/kg bodyweight may prove beneficial for presurgical patient management decisions by more accurately defining the extent of disease in patients with cerebral gliomas or brain metastases. Better definition of radiosurgical target volumes and better selection of patients for whom surgical intervention would not prove beneficial may potentially improve prognosis or quality-of-life in this group of patients.

                  2192.     Initial Area Under the Curve (IAUC) is an Objective, Pragmatic and Translatable MRI Biomarker
                                 for Quantifying Human Brain Tumor Perfusion: Correlation with Histopathology

Bradford Armstrong Moffat1, Catherine Klotz2, Amanda Lovell2, Soren Christensen2, Patricia M. Desmond2

1University of Melbourne, Parkville , Australia; 2University of Melbourne, Parkville, Australia

In this study the normalized initial area under the time curve (IAUC) was quantified in 21 high grade brain tumor patients. This model free analysis allowed for a completely objective measure of brain tumor perfusion.  In addition it was able to distinguish and predict WHO histopathological subtype.  This suggests that IAUC has the potential to be a pragmatic and translatable MRI biomarker for imaging brain tumor angiogenesis.

                  2193.     Contrast-Enhanced MR Imaging of the Central Nervous System in Children: Evaluation of
                                 Gadobenate Dimeglumine

Matthew J. Kuhn1, Pei-yi Gao2, Claudio Fonda3, Emilio Cianciulli4, Mieczyslaw Pasowicz5

1Southern Illinois University, Springfield, Illinois, USA; 2Beijing Tian Tan Hospital, Beijing, People's Republic of China; 3Anna Meyer Pediatric Hospital, Florence, Italy; 4 “Santobono Pausillipon” Children’s Hospital, Naples, Italy; 5John Paul II Hospital, Krakow, Poland

A multinational clinical trial of the safety and efficacy of 0.1 mmol/kg Gd-BOPTA for MRI of the CNS in children is described. To date, 71 children have been enrolled. Gd-BOPTA was well tolerated by all children enrolled: 4 mild adverse events have been reported, and no clinically meaningful changes in laboratory parameters/ECGs have been observed. In all children with enhancing lesions, contrast enhancement was considered good to excellent. Compared to unenhanced images, Gd-BOPTA resulted in improved evaluation of the extent of disease, lesion border delineation, and lesion internal morphology.

                  2194.     The Functional Perfusion Map: A Novel Imaging Biomarker for Early Prediction of Tumor Patient Response

Craig J. Galbán1, Daniel A. Hamstra1, Charles R. Meyer1, Pia Sundgren1, Christina Tsien1, Theodore S. Lawrence1, Alnawaz Rehemtulla1, Thomas L. Chenevert1, Brian D. Ross1

1University of Michigan, Ann Arbor, Michigan, USA

We describe a novel, perfusion MRI approach which provides an imaging biomarker capable of early prediction of treatment response in glioma patients.  Perfusion MRI was performed on 45 patients pre and post-treatment.  Voxel-wise differences in relative cerebral blood volume (rCBV) maps were calculated as a functional perfusion map (fPMrCBV).  Survival analysis was performed by stratification of patient outcome based on fPMrCBV or percent difference of mean rCBV.  In contrast to mean rCBV, overall survival was closely associated to fPMrCBV.  This study provides a potentially standardized method for using perfusion MRI as an early predictor of cancer patient treatment response.

                  2195.     Self-Learning Predictive Modeling in Glioma Grading

Kyrre Eeg Emblem1, 2, Bjorn Tennoe1, Baard Nedregaard1, Terje Nome1, Paulina Due-Tonnessen1, John K. Hald1, David Scheie1, Atle Bjornerud1, 2

1Rikshospitalet, Oslo, Norway; 2University of Oslo, Oslo, Norway

Studies have shown that cerebral blood volume (CBV) maps derived from MR perfusion can improve glioma grading. However, the current grading methods are prone to user-bias. An important step towards a user-independent, automated glioma grading is the need to develop self-learning predictive models. In this study, we have developed and evaluated four self-learning predictive models based histogram analysis of CBV heterogeneity. Preliminary results suggest that the predictive models are able to correctly predict glioma grade in 7-8 out of 10 patients, and the ability to correctly grade new glioma cases increase with the number of cases in the reference database.

                  2196.     DSC-MRI Estimates of Perfusion Predict Survival in Brain Tumor Patients

Kathleen Marie Schmainda1, 2, Devyani Bedekar1, Eric S. Paulson1, Scott D. Rand1, Hendrikus G J Krouwer

1Medical College of Wisconsin, Milwaukee, Wisconsin, USA

Survival is the primary measure used to evaluate the success of new treatments in brain tumor and other patients.  However, analysis of survival requires studying a large cohort of patients and estimating survival long after the treatment study has ended.  Consequently, an imaging biomarker, which is predictive of survival early on, has the potential to improve the efficiency of clinical drug trials and patient management in the short term.  Here we demonstrate that both GE rCBV (relative cerebral blood volume) and mVD (mean vessel diameter) information, derived from DSC perfusion studies, and obtained at initial diagnosis are predictive of survival.

                  2197.     MR Perfusion Imaging and Voxel-Based Diffusion Tensor Imaging of Non-Enhancing Cerebral Gliomas
 [Not Available]

Xiang Liu1, Wei Tian1, Sven Ekholm1, Per-Lennart Westesson1

1University of Rochester School of Medicine & Dentistry, Rochester, New York, USA

14¨C45% of non-enhancing supratentorial gliomas, which are usually misdiagnosed as low grade glimoas (WHO grade 1and 2) because of lack of enhancement, are malignant(WHO grade 3 and 4). Thus it is important of correct  pre-operative grading in non-enhancing cerebral gliomas, but which is difficult by conventional MR imaging. We speculate that MR perfusion weighted imaging(PWI) and diffusion tensor imaging(DTI) will be benefit for differentiating low grade with high grade non-enhancing supratentorial gliomas. 33 patients with pathology confirmed non-enhancing supratentorial glioma were enrolled in this study. Maximal ratio of relative cerebral blood volume (rCBV), trace apparent diffusion coefficient ( trace ADC) and Fractional anisotropy (FA) in the tumor were calculated and compared between low grade group and high grade group. There is significant difference of maximal ratio of rCBV and FA between low grade(rCBV 0.931¡À0.056, FA 0.128¡À0.033 ) and high grade group(rCBV 3.91¡À2.87, FA 0.356¡À0.133) (P=0.000, by Mann-Whitney U test) . About 96% patients could be classified correctly based on maximal ratio of rCBV of 1.75 and cutoff FA value of 0.21. There is no significant difference of mean trace ADC value between groups(P>0.05).  Our study proves that there is increased perfusion and higher anisotropy changes in the high grade non-enhancing supratentorial glioma. Combing MR PWI and DTI are useful in the accurate pre-operative grading non-enhancing supratentorial gliomas.

                  2198.     MR Measurements of Pre-Treatment Tumour Perfusion Appear to Correlate with Response to
                                Dexamethasone in Patients with Gliobastoma Multiforme

Paul A. Armitage1, Chris Schwindack1, Mark E. Bastin1, Ian R. Whittle1

1University of Edinburgh, Edinburgh, UK

Dynamic susceptibility contrast MRI (DSC-MRI) and dynamic contrast-enhanced MRI (DCE-MRI) were used to obtain measurements of tumour perfusion and permeability in a series of nine glioblastoma multiforme patients imaged before and 48 -72 hr following administration of dexamethasone.  Pre-treatment tumour perfusion was correlated with pre-post treatment changes in DCE-MRI parameters.  A strong correlation was found between pre-treatment tumoural blood flow and tumoural blood volume and the resulting treatment effect as measured by DCE-MRI.  The results suggest that pre-treatment measurements of tumour perfusion may be useful predictors of response to brain tumour therapies.

                  2199.     Differentiation of Recurrent Intra-Axial Metastatic Tumor from Delayed Radiation Effects of Gama Knife
                                Radiosurgery Using Dynamic Susceptibility Weighted Contrast Enhanced Perfusion MR Imaging

Ramon Francisco Barajas Jr. 1, Jamie Chang1, Patricia K. Sneed, Soonmee Cha

1University of California San Francisco, San Francisco, California , USA

The purpose of our study was to determine whether relative cerebral blood volume (rCBV), relative peak height (rPH), and percentage of signal intensity recovery (PSR) derived from DSC perfusion MR imaging can differentiate recurrent tumor from the delayed effects of radiation in patients previously treated with gamma knife radiosurgery for metastatic intra-axial tumors.  Thirty four cases were retrospectively investigated by drawing regions of interest around contrast enhancing areas producing T2* signal intensity-time curves.  We found that mean PSR values were lower (P <0.01) and rCBV and rPH values were higher (P <0.024) in cases of recurrent tumor.

                 2200.     Preclinical MRI Evaluation of Human Glioblastoma Response to an Anti-Angiogenic Treatment

Benjamin Lemasson1, 2, Thomas Christen2, 3, Regine Farion2, 3, Emanuel Barbier2, 3, Xavier Tizon1, Christoph Segebarth2, 3, Philippe Genne1, Olivier Duchamp1, Chantal Remy2, 3

1Oncodesign Biotechnology, Dijon, France; 2Inserm U836, Grenoble, France; 3Université Joseph Fourier, Grenoble Institut des Neurosciences UMR-S836, Grenoble, France

Despite aggressive surgery, radiotherapy and chemotherapy, malignant gliomas remain uniformly fatal. These tumours stimulate the formation of new blood vessels (angiogenesis). Therapies directed against tumour vasculature or preventing angiogenesis have recently been developed. Monitoring changes in microvasculature should help to evaluate the efficiency of anti-angiogenic therapies. Recently, MRI has shown its ability to map different microvascular parameters. Moreover, they have the sensitivity to reveal differences between normal and tumoral tissues as well as differences between tumour types. The aim of this work was to apply MRI to evaluate the efficiency of a particular anti-angiogenic therapy on a human glioma model.

                  2201.     Images of Restricted Water in Brain with Applications to Neurosurgery

Sharon Peled1, Stephen Whalen, Ferenc Jolesz1, Alexandra Golby

1Brigham and Women's Hospital, Boston, Massachusetts, USA

DTI-based fiber tracking in white matter has become a useful tool for preoperative planning of brain tumor surgery. However, edema and/or tumor infiltration can cause the diffusion anisotropy to be low, causing tractography algorithms to fail in critical areas around tumors. Here we show a clinically applicable DTI-based method for identifying where viable intracellular space still exist by isolating the signal from restricted water in each voxel. The ability to quantify this water also provides a new contrast mechanism whose sensitivity to different pathological states of tissue is under evaluation.

                  2202.     The Use of ADC Parameters to Distinguish Paediatric Brain Tumours

Jonathan G. Bull1, Martin D. King1, Dawn E. Saunders2, Christopher A. Clark1

1UCL Institute of Child Health, 30 Guilford Street, UK; 2Great Ormond Street Hospital for Sick Children, Great Ormond Street, UK

A study to discrminate different paediatric brain tumour types using ADC histograms of the tumour volume in 56 histopathologically verified cases. We show that using linear discriminant analysis of the ADC histogram parameters it is possible to discriminate the 3 common posterior fossa tumours and to differentiate between a rare agressive tumour atypical teratoid rhabdoid tuumour (ATRT) and medulloblastoma. This is currently not possible pre-operatively. These findings may diminsh the need for invasive surgical biopsy and its attendant risk of morbidity and mortality.

                  2203.     Serial Diffusion Tensor Imaging Study in Children Receiving Cranial Radiation

Firouzeh Tannazi1, Todd McNutt1, Siamak Ardekani2, Doris Lin1, Ori Shokek1, Kenneth Cohen1, Moody Wharam1, Peter Barker1, Susumu Mori3, Alena Horska3

1Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; 2Johns Hopkins University, Baltimore, Maryland, USA; 3Johns Hopkins University School of Medicine,, Baltimore, Maryland, USA

A longitudinal DTI based study was conducted to examine white matter injury associated with radiation therapy (RT) in children with brain tumor. Six patients (8.7-18.7 years old) were examined before, 6, and 15 months after RT. Results were compared to 27 aged matched control subjects (scanned with the same intervals). Initially, in comparison to control subjects, significant drop in FA and increase in ADC values in several regions were detected. However, in 6 and 15 months follow-ups the diffusion parameters tended toward control values. This observation may suggest DTI can capture recovery of brain from acute side effects of radiation.

                  2204.     A Study of Correlation Between Neovascularity and Tumor Infiltration of Gliomas Using Perfusion
                               and Diffusion MRI
 [Not Available]

Shuohui Yang1, John L. Villano1, Girish Srinivasan1, 2, Keith R. Thulborn1, Xiaohong Joe Zhou1

1Univ. of Illinois Medical Center, Chicago, USA; 2University of Illinois at Chicago, Chicago, USA

Neovascularity and tumor infiltration are important characteristics defining glioma growth and aggressiveness. In this study, we have investigated the possible correlation between neovascularity and tumor infiltration of low-grade and high-grade gliomas by employing both perfusion and diffusion tensor imaging (DTI) techniques.  Our result in general did not support a spatial correlation between neovascularity revealed by perfusion imaging and tumor infiltration assessed by two DTI parameters.  However, the combination of DTI and perfusion imaging may be useful to reveal the temporal relationship between neovascularity and tumor infiltration through a time-course study.

                  2205.     Behavior of DTI Parameters as Functions of Distance from a Tumor

Ashok Kumar1, Weiting T. Zhang1, E di Tomaso2, D G. Duda2, R K. Jain2, T T. Batchelor2, Alma Gregory Sorensen1

1A. A. Martinos Center, Massachusetts General Hospital, Charlestown, Massachusetts, USA; 2Masschusetts General Hospital, Boston, Massachusetts, USA

Water-diffusion parameters have a dominant localized behavior as a response to injury.  That is, the diffusion tensor eigenvalues vary monotonically from the site of the injury and assume a more normal value far away from the injury.  Differerent eigenvalues may vary at different rates with distance.  So even though each of them may show a monotonic response, due to their different rates of change, their combined effect on FA is to create a more complicated behavior with distance.

                  2206.     Quantification of Therapy Induced Cerebral Blood Flow Changes in Pediatric Diffuse Pontine Gliomas
                                 and Normal Appearing Brain Parenchyma by Arterial Spin Labeling During Phase I Combined Radiation
                                 and Antiangiogenesis Therapy

Yong Zhang1, Fred H. Laningham1, Ralf Loeffler1, Ruitian Song1, Josef Pfeuffer2, Alberto Broniscer1, Zoltan Patay1, Claudia M. Hillenbrand1

1St. Jude Children's Research Hospital, Memphis, USA; 2Siemens Medical Solutions, Erlangen, Germany

We used pulsed arterial spin labeling (PASL) to evaluate brain perfusion changes in the first four pediatric patients enrolled in a new Phase I study of diffuse pontine glioma treated with a combination of local radiotherapy and an anti-angiogenic drug.  Cerebral blood flow (CBF) measurements were performed in both normal appearing brain parenchyma and in tumor regions at three sequential time points.  A similar trend of CBF changes were observed in both regions.  Initial success of PASL in detecting and quantifying CBF changes offers potential to use this technique to monitor changes in tumor vasculature induced by treatment.

 

Imaging Traumatic Brain & Spine Injury

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  2268.     Quantitative T2 But Not Lesion Volume Correlates with Functional Outcome After Traumatic Brain Injury
 [Not Available]

Alejandra Sierra1, Irina Kharatishvili1, Riikka Immonen1, Asla Pitkänen1, Olli Gröhn1

1A. I. Virtanen Institute for Molecular Science, University of Kuopio, Kuopio, Finland

In traumatic brain injury (TBI) model the animal variety is large. The aim of this study was to test if simple MRI measurements correlate with the functional outcomes measured using behavioural tests. Quantitative T2 measurement was correlated with Beam Balance and neuroscore tests. T2 changes were also detected in the hippocampus and correlated with the Morris Water Maze test. These findings suggest that T2 mapping in lesion and hippocampus 3 days after TBI is an indicator of the functional impairment and has potential as a clinical marker for severity of post traumatic tissue damage.

                  2269.     DTI-Tractography to Detect and Quantify Brain Pathways Affected in Traumatic Brain Injury

Manbir Singh1, Jeong-Won Jeong1

1University of Southern California, Los Angeles, California , USA

DTI-tractography is ideally suited to detect axonal injury in traumatic brain Injury (TBI) and quantify disruptions along affected pathways.  We have conducted a study where FA maps of four TBI subjects were compared individually to those of 10 normal controls in a standard MNI space to reveal injured regions, which were then used as ROIs to sort and quantify normalized tracts from individual subjects. Results show several regions in individual TBI subjects with significantly reduced FA values (p<0.001), but no regions where FA increased in TBI. ROI sorted tracts in MNI space show significant connectivity reduction along several critical pathways.

                  2270.     3D MRSI of Traumatic Brain Injury Patients at 3T

Duan Xu1, 2, Srivathsa Veeraraghavan1, Qian Zhao1, Hana Lee1, Michele R. Meeker1, Ying Lu1, Jamshid Ghajar3, Geoffrey T. Manley1, Daniel B. Vigneron1, 2, Pratik Mukherjee1

1UCSF, San Francisco, California , USA; 2UCSF/UC Berkeley, San Francisco/Berkeley, California , USA; 3Brain Trauma Foundation, New York, New York, USA

With 1.4 millions of Americans suffering from traumatic brain injury, better diagnosis and treatment planning is needed. In this study, 3D MRSI at 3T was performed on moderate-severe and mild TBI patient groups, and on matched control subjects, confirming previous 1.5T MRSI and whole brain NAA analyses of decreased NAA following injury.  NAA/CHO ratios were 1.55±0.14, 1.87±0.41, 1.94±0.51 for moderate-severe, mild, and control groups, respectively. However, only the moderate-severe TBI patient group demonstrated a statistically significant difference (P<<0.01) compared to control subjects.  In the longitudinal study of the mild TBI patients within 2 weeks, at 1 month and at 1 year, a trend towards decreasing NAA/Cho ratio did not reach statistical significance (P=014).

                  2271.     Pathophysiological Changes in Pericontusional Tissue Post Traumatic Brain Injury: A Diffusion Tensor
                                 Imaging Study

Virginia F. Newcombe1, Guy B. Williams1, M G. Abate1, Doris A. Chatfield1, Joanne G. Outtrim1, Sally G. Harding1, Jonathan P. Coles1, Jonathan H. Gillard1, Peter J. Huchinson1, John D. Pickard1, T Adrian Carpenter1, David K. Menon1

1Cambridge University, Cambridge, UK

Perilesional tissue is a major component of the traumatic penumbra, where physiology is deranged, but clinical interventions may enhance tissue survival. The time course of imaging changes in such target tissue is not well described. We have used diffusion tensor imaging (DTI) to understand temporal changes in pathophysiology around contusions and traumatic intracerebral haematomas, and identify possible biomarkers. This study describes the heterogeneity within lesions and their evolution following acute TBI.

                  2272.     Region of Interest Analysis of DTI FA Histogram Differentiates Mild Traumatic Brain Injury from Controls

Zhifeng Kou1, Ramtilak Gattu2, Randall R. Benson2, Naftali Raz2, E Mark Haacke1

1Wayne State University School of Medicine, Detroit, Michigan, USA; 2Wayne State University, Detroit, Michigan, USA

Autopsy data revealed that, in diffuse axonal injury, the corpus callosum (CC), internal capsule, and rostral part of brain stem are major locations of damage. It is still unknown how DTI findings are consistent with reported autopsy data on the regional locations of brain damage. This study is to investigate whether CC is a major location for DTI signal changes after brain injury. Our regional FA histograms of the whole CC and the body of CC showed prominent group differences between MTBI and controls. Our DTI ROI analysis of CC may serve as a hallmarker of mild traumatic brain injury.

                  2273.     Unique Changing Patterns of DTI Parameters Associated with Sport-Related Concussions from
                                 Wild Bootstrap Analysis

Tong Zhu1, Madalina Tivarus, Jeffray Bazarian, Jianhui Zhong

1University of Rochester, Rochester, New York, USA

Complexities in changing patterns of DTI parameters under sports related concussions as well as the induced mild Traumatic Brian Injury (mTBI) reflect the complex nature of the underlying pathological progress. The mechanical forces during concussions not only cause commonly patterns of axonal injury in vulnerable brain regions but also may result in subject-dependent impact. In this study, we applied a wild bootstrap based analysis in a group of high school hockey and football players to investigate the subject-dependent DTI changing patterns. The spatial locations as well as the levels of DTI changes are shown to be subject-dependent that are not easily detected by the ROI-based or group analysis. Unique patterns of elevated FA and reduced MD under concussion presented in this study is most likely due to the axonal swelling during the process of axonal injury.

                  2274.     Volumetric MRSI of Metabolic Alterations with Traumatic Brain Injury

Varanavasi Govindaraju1, Steven F. Falcone1, Jonathan R. Jagid1, Andrew A. Maudsley1

1University of Miami, Miami, Florida, USA

Volumetric 1H MRSI at 3 T has been obtained in subjects with mild and moderate traumatic brain injury. Results indicate significant and widespread alterations of metabolite ratios within all brain regions in comparison to control subjects, with the strongest effect being increased choline/NAA in white matter regions throughout the cerebrum.

                  2275.     Voxel-Based Diffusion Tensor Imaging Study of Mild Traumatic Brain Injury  [Not Available]

Zili Chu1, 2, Elisabeth A. Wilde3, Stephen R. McCauley3, Jill V. Hunter1, 2, Erin D. Bigler4, 5, Maya Troyanskaya3, Ragini Yallampalli3, Jonathan M. Chia6, Harvey S. Levin3

1Baylor College of Medicine, Houston, USA; 2Texas Children's Hospital, Houston, Texas, USA; 3Baylor College of Medicine and the University of Texas-Houston Medical School, Houston, Texas, USA; 4Brigham Young University, Provo, Utah, USA; 5University of Utah, Utah, USA; 6Philips Medical Systems, Cleveland, Ohio, USA

In many cases, early detection of mild TBI is complicated by unremarkable CT and conventional MRI, despite patient complaints of post-concussion symptoms  including memory loss, attention problems and anxiety. This work presents a voxel-based diffusion tensor imaging (DTI) study exploring the underlying structural basis of the somatic, affection and cognitive deficits after MTBI. All injury-affected regions showed marked decreased radial diffusivity despite minimally changed axial diffusivity, consistent with axonal swelling secondary to cytotoxic edema as the probable mechanism of injury. The findings demonstrated the feasibility and potential utility of using DTI as a diagnosis and evaluation tool in acute MTBI.

                  2276.     Diffusion Tensor Imaging Parameters of Apparent Diffusion Coefficient and Fractional Anisotropy in the
                                 Evaluation of Traumatic Cervical Spine Injury
 [Not Available]

Sendhil Kumar Cheran1, Kathirkamanathan Shanmuganathan1, Jiachen Zhuo2, Stuart E. Mirvis1, Rao P. Gullapalli2

1University of Maryland Medical Center, Baltimore, Maryland, USA; 2University of Maryland School of Medicine, Baltimore, Maryland, USA

This retrospective study compared DT-MRI parameters of ADC and FA in 11 controls and 50 patients with blunt traumatic cervical spine injury.  ADC and FA were measured in the upper, middle, and lower cervical cord regions.  Patients were divided into 4 subgroups of expected injury severity and compared to controls. ADC decrease reflects the severity of injury. FA shows significant decrease in the middle and lower cervical spinal cord of all patient groups. ADC and FA changes were found even in the absence of cord contusion by conventional MRI sequences.

                  2277.     Traumatic Extra-Axial Hemorrhage: Correlation of Postmortem MSCT, MRI, and Forensic-Pathological
                                  Findings

Eva Scheurer1, 2, Javier Anon, Luca Remonda, Adrian Spreng, Gerhard Schroth, Michael Thali1, Kathrin Yen3, Chris Boesch2

1University Bern, Bern, Switzerland; 2University Bern & Inselspital, Bern, Switzerland; 3Medical University Graz, Graz, Austria

Diagnosis of traumatic extra-axial hemorrhage is of paramount importance in forensic investigations of living or dead injured subjects in order to determine the legally relevant evolution of fights and accidents. Imaging techniques are increasingly used in forensic medicine to complement or even replace invasive methods. Thus, the diagnostic accuracy of postmortem multi-slice computed tomography (MSCT) and magnetic resonance imaging (MRI) was retrospectively evaluated using subsequent autopsy as a reference standard. CT and MRI are of comparable potential in forensic medicine as diagnostic tools for traumatic extra-axial hemorrhage in living or dead injured subjects.

 

Manganese in the Brain: Method & Application

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                   2313.     Detection of Olfaction Induced Activation in the Brain After Systemic Manganese Infusion

Otto Heikki Henrikki Manninen1, Toni Aittoniemi1, Arto Lipponen1, Heikki Tanila1, Olli Gröhn1

1University of Kuopio, Kuopio, Finland

The aim of this study was to test whether activation dependent MEMRI using systemic Mn adminstration with intact BBB is feasible in the olfactory system. We detected significant differences in T1 between the stimulated and the control groups at the olfactory bulb but not in the olfactory cortex.It appears that activation dependent MEMRI with systemic Mn administration with intact BBB is possible only in specific brain regions that have naturally more permeable blood-brain barrier.

                  2314.     Pharmacological Manganese-Enhanced MRI (PhMEMRI) Without Osmotic Breakdown of the Blood
                                 Brain Barrier

Alessandro Gozzi1, Adam Schwarz1, Valerio Crestan1, Angelo Bifone1

1GlaxosmithKline Medicine Research Centre, Verona, Italy

The application of MEMRI to pharmacological studies could complement phMRI approaches that measure haemodynamic responses as a surrogate. Although manganese does not readily cross the BBB, we recently observed that continuous infusion of MnCl2 can produce weak but reproducible MEMRI signal increases in rat brain parenchyma. Here we have investigated whether this intrinsic permeability can be exploited to map drug-induced MEMRI signal changes in the brain. Amphetamine challenge elicited a bilateral pattern of MEMRI signal increases consistent with previous haemodynamic and metabolic studies. These data suggest the feasibility of functional MEMRI without the need of invasive procedures to breakdown the BBB.

                  2315.     3D Statistical Mapping of Odor Induced Differences in Manganese Uptake in the Mouse Olfactory System

Waqas Majeed1, Matthew Magnuson1, Kerry Ressler, Mike Davis, Shella Keilholz1

1Georgia Institute of Technology / Emory University, Atlanta, Georgia, USA

In this abstract, we report odor-induced differences in enhancement 42 hours after nasal administration of manganese chloride.

                  2316.     Detection of Thalamocortical Inputs of the Rat Whisker Barrel Field Using Manganese Enhanced MRI

Jason Tucciarone1, Alan Koretsky1

1National Institutes of Health, Bethesda, USA

The goal of this work was to determine if neural track tracing using manganese enhanced MRI (MEMRI) can distinguish individual thalamocortical inputs to whisker barrels of the barrel field cortex of the rat. Three to five hours post injection of manganese into the ventral posteriormedial thalamic nucleus revealed a narrow band of layer four enhancement confined to the whisker barrel field cortex. Additionally, the T1 enhancement had a periodic structure consistent with the size and location of whisker barrels. This technique has potential applications to investigate anatomical changes in the whisker barrel cortex during plasticity in individual rodents.

                  2317.     Reproducible Imaging of Rat Corticothalamic Pathway by Using Longitudinal Manganese-Enhanced
                                 MRI (L-MEMRI)

Guadalupe Soria1, Dirk Wiedermann1, Carles Justicia2, Pedro Ramos-Cabrer3, Mathias Hoehn1

1Max Planck Institute for Neurological Research, Cologne, Germany; 2Institut d'Investigacions Biomediques de Barcelona-Consejo Superior de Investigaciones Cientificas, Barcelona, Spain; 3Hospital Clinico Universitario-Universidad Santiago de Compostela, Santiago de Compostela, Spain

Our objective was to optimize the experimental conditions of MEMRI to study the somatosensory pathway longitudinally, and to provide functional information on rat corticothalamic connectivity in parallel with fMRI. Animals received repetitive MnCl2 injections. Spatiotemporal patterns showed a significant hyperintensity induced by manganese transport in structures related to the somatosensory pathway. Parallel fMRI experiments showed that fMRI studies and longitudinal MEMRI can be performed in the same animals. We demonstrate, for the first time, a reliable and reproducible technique to perform longitudinal MEMRI to study the time-course changes of the corticothalamic connections following stroke in the rat. 

                  2318.     Neural Substrate of Chronic Neuropathic Pain in Mice Revealed by Manganese-Enhanced MRI

Chun-Xia Li1, Wen-Ju Pan1, Hao Lei1

1Wuhan Institute of Physics and Mathematics, Chinese Academy of Science, Wuhan, People's Republic of China

Manganese-enhanced magnetic resonance imaging (MEMRI) was used to mapping and assessing brain activation pattern of chronic neuropathic pain induced by the chronic constriction injury (CCI) in waken, free moving mice. The data obtained indicated that chronic neuropathic pain induced by CCI involves not only neural activation of the supraspinal structures participating in pain perception and modulation, but also deactivation of descending antinociceptive system and the reward system.

                  2319.     Optic Nerve Damage of EAE Mice Detected by DTI But Not by MEMRI

Shu-Wei Sun1, Sheng-Kwei Song1

1Washington University School of Medicine, St Louis, Missouri, USA

In this study, the feasibility of using MEMRI to detect the optic nerve (ON) damage induced by experimental autoimmune encephalomyelitis (EAE), an animal model for human MS, was evaluated. Since axial and radial diffusivities derived from diffusion tensor imaging (DTI) have been reported to detect ON injury in the EAE mice, these parameters were also measured to compare with MEMRI findings.  Our results showed that although axonal and myelin damage was detected by significantly decreased axial and increased radial diffusivities in ON from EAE mice, MEMRI showed no significant difference between EAE and control mice.

                  2320.     Negative MEMRI in Optic Nerve After Transient Retinal Ischemia

Shu-Wei Sun1, Matthew D. Budde1, Sheng-Kwei Song1

1Washington University School of Medicine, St Louis, Missouri, USA

In this study, the feasibility of using MEMRI to detect optic nerve damage after transient retinal ischemia was evaluated.  The results showed that although intensive Mn2+ accumulated in the vitreous space was noticeable in MEMRI, no passive diffusion of the ion into the intra- and inter-cellular space of visual pathway was observed. Damage manifested as significantly reduced MEMRI enhancement in the optic nerve as well as the decreased axial diffusivity without changes in radial diffusivity derived from DTI.  This study demonstrated that the uptake of Mn2+ requires functional neuronal cells (the retinal ganglion cells) and the intact axonal transport system.

                  2321.     Glial Tissue Imaging at Ischemic Legion by MEMRI Using Manganese Oral Administration

Yuko Kawai1, Masahiro Umeda1, Yasuharu Watanabe1, Toshihiko Higuchi1, Chuzo Tanaka1

1Meiji University of Oriental Medicine, Kyoto, Japan

We succeeded to detect of brain signal enhancement at the ischemic lesion after oral administration of manganese as drinking water continuously after onset of ischemia. We made the temporary middle cerebral artery occlusion (MCAO) model. After MCAO, we started oral administration of manganese solution. T1-W and DWI were acquired during one month after MCAO using a 4.7T-MRI. The signal enhancement of ischemic region was confirmed in oral administration group. With the method of continuous oral dosage of a little manganese, it was suggested that the manganese was accumulated and changed a signal of the brain.

                  2322.     Utilizing MEMRI to Screen Drug Therapies in Mouse Models:  the Effect of an Aβ 1-42 Lowering Drug,
                               R-Flurbiprofen, on Axonal Transport Rates in an Alzheimer's Disease Mouse Model

Karen Dell Brown Smith1, Robia G. Pautler1

1Baylor College of Medicine, Houston, USA

R-Flurbiprofen is a non-steroidal anti-inflammatory drug (NSAID) that has been shown to reduce A[beta] 1-42 levels and is currently being employed in clinical trials as a potential therapy for Alzheimer’s Disease (AD). Utilizing MEMRI, we report that treatment of the Tg2576 mouse model AD with R-Flurbiprofen shows marked improvement of previously reported axonal transport deficits.  These data implicate A[beta] 1-42 as having a deleterious effect on axonal transport and support the use of MEMRI as a pharmacological screening tool in mouse models.

                  2323.     Variations of Intensity Patterns of Manganese-Labeled Corticospinal Tract with Spinal Levels

Mehmet Bilgen1

1Medical University of South Carolina, Charleston, USA

Manganese-enhanced MRI (MEI) offers a novel neuroimaging tool to anterogradely trace corticospinal tract (CST) in live rats and detect axonal fiber connectivity in injured spinal cord (SC).  Anatomically, the transverse size and shape of SC as well as its gray matter white matter intensity pattern varies in cervical, thoracic, lumbar and sacral levels.  The same is true for the CST.  Our goal is to establish baseline intensity patterns of manganese-labeled CST in different levels of SC in normal rat.  This normative data would allow detecting any changes due to dysfunctional axonal fibers as a result of SCI or neuropathological alterations.

                  2324.     Signal Enhancement Achieved Through Hypotonic Bath Application of Manganese Chloride in
                                MR Microscopy of the Rat Hippocampal Brain Slice Model

Jeremy J. Flint1, Choong H. Lee1, Timmothy M. Shepherd1, Stephen J. Blackband1, 2

1University of Florida, Gainesville, USA; 2Natonal High Magnetic Field Laboratory , Tallahassee, USA

The present study investigates our ability to achieve signal to noise increases and contrast enhancement in the brain-slice model using bath application of hypotonic solutions containing low concentrations of manganese chloride (10μM to 100μM). Manganese concentrations above 10μM elicited significant signal increases compared to control groups. These signal enhancement effects were still present 24 hours following the initial exposure to manganese. Concentrations above 60μM resulted in non-native contrast enhancement of specific hippocampal lamina while concentrations above 100μM resulted in drastic signal loss due to manganese's T2-shortening effects. Future studies will concentrate on optimizing manganese concentration as a function of TR.

 

Novel fMRI Techniques

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  2360.     A New Real-Time Functional Magnetic Resonance Imaging Method for Neurofeedback

Audrey Yu Ching Kuo1, Charles H. Cunningham1, Simon James Graham1

1University of Toronto, Toronto, Canada

As an alternative to commonly used fMRI methods for on-line visual feedback during an fMRI neurofeedback (NF) experiments such as EPI or spiral imaging, an imaging technique is developed that localizes a column of tissue using outer volume suppression and provides multi-echo (ME) acquisition to sample T2* decay in great detail. The advantages of this technique are enhanced BOLD contrast sensitivity by echo summation and reduced data processing time due to reduced data size.  These advantages were confirmed by experiment, indicating that the implementation and validation of the prototype ME acquisition technique has favorable features for performing fMRI NF experiments.

                  2361.     Enhanced BOLD Effect in the Mouse Brain with Fast CRAZED Imaging at High Magnetic Fields

Johannes Thomas Schneider1, Cornelius Faber1

1University of Wuerzburg, Wuerzburg, Germany

A fast CRAZED sequence detecting the signal from intermolecular multiple-quantum coherences (iMQC) was implemented at 17.6 T to observe the BOLD effect in the mouse brain. Signal readout as echo train employing a four-step phase cycle for the refocusing pulses and an intensity-ordered k-space sampling allowed for acquisition of CRAZED images in 30 seconds. In the CRAZED images the BOLD effect was more pronounced than in RARE images but smaller than in gradient echo images. Combination of iMQC with T2*-effects may provide larger signal changes than conventional BOLD methods.

                  2362.     Efficient High Resolution FMRI at 7T

Anders Nordell1, Samantha Holdsworth2, Rexford Newbould2, Roland Bammer2, Stefan Skare2

1Karolinska University Hospital, Stockholm, Sweden; 2Stanford University, Palo Alto, California , USA

In this work we perform a high resolution fMRI experiment at 7T using a gradient echo Short Axis propeller readout EPI (SAP-EPI) sequence. GRAPPA accelerated SAP-EPI is much less susceptible to image distortion than conventional single shot EPI and has further properties that enable high resolution while maintaining good temporal resolution and volume coverage. The echo time was chosen sufficiently long so that the bulk of the BOLD response originated from extravascular tissue.

                  2363.     Increased Specifity in Functional Magnetic Resonance Imaging from Vessel-Size Estimates

Thies H. Jochimsen1, Harald E. Moeller1

1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

A general problem with the BOLD contrast is its inability to properly localize the region of activity. Rather, the contrast reflects changes in blood oxygenation which can be distant from the activated site, e.g. in the presence of large veins. In this work, the approach of vessel-size imaging was employed using deoxygenated hemoglobin as the contrast agent to increase the specifity of the BOLD contrast. This was achieved by classifying activated voxels according to their microstructure, i.e. the average vessel radius, in order to filter out voxels which contain predominantly large vessels.

                  2364.     Optimized Acquisition of Susceptibility Weighted Imaging (SWI) at 7T

Andreas Deistung1, Alexander Rauscher2, Jan Sedlacik1, Jürgen R. Reichenbach1

1Hospital of the Friedrich Schiller-University, Jena, Germany; 2UBC MRI Research Centre, Vancouver, Canada

Since the relaxation times of blood and brain tissues at 7T are very different from the values obtained at lower field strengths a linear relationship between SWI contrast, echo time (TE) and field strength cannot be assumed. To determine the optimum echo time for SWI at 7T we simulated the complex signal decay of venous vessels in the subvoxel regime as well as the contrast to WM for different aspect ratios (slice thickness : inplane resolution) and blood volume fractions. The simulation and in vivo measurements revealed an optimum SWI contrast for TE»14ms with voxel aspect ratios larger than 2.

                  2365.     Integration of Generalized Series and Parallel Imaging (GS-Parallel) for High-Resolution FMRI

Sungdae Yun1, Sung Suk Oh1, Yeji Han1, HyunWook Park1

1Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea

BOLD fMRI is a technique to study brain function, which requires a high spatiotemporal resolution. To satisfy this requirement, the EPI has been widely used. While the resolution of EPI is sufficient for most fMRI, it is inadequate for studying brain function at the millimeter level. With the EPI technique, it is very difficult to increase the resolution of the fMRI data due to the T2* decay. In this study, we propose a high spatiotemporal resolution MRI technique that combines the parallel MRI and the generalized series techniques with the conventional gradient-echo sequence for fMRI at high magnetic fields.

                  2366.     fMRI with 16 Fold Reduction Using Multibanded Multislice Sampling

Steen Moeller1, Eddie Auerbach1, Pierre-Francois van de Moortele1, Gregor Adriany1, Kamil Ugurbil1, 2

1University of Minnesota, Minneapolis, Minnesota, USA; 2Max Planck Institute for Biological Cybernetics, Tubingen, Germany

Multiband multislice acquisition with a 16 channel head coil at 7Tesla is investigated for parallel imaging performance and reconstructions using both GRAPPA and SENSE.  With GE-EPI,   functional MRI studies with 16 fold reduction, and maximal aliasing of 12 is demonstrated for combined visual and motor studies.

                  2367.     Single-Shot Echo-Volumar Imaging Using Highly Parallel Detection

Thomas Witzel1, 2, Jonathan R. Polimeni2, Graham C. Wiggins2, FaHsuan Lin, 23, Stephan Biber4, Michael Hamm5, Ravi Seethamraju5, Lawrence L. Wald2

1Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, USA; 2Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, USA; 3National Taiwan University, Taipei, Taiwan; 4Siemens Medical Solutions AG, Erlangen, Germany; 5Siemens Medical Solutions Inc., Malvern, Pennsylvania, USA

Volumetric imaging holds intrinsic sensitivity advantages. FMRI, however, benefits from single-shot acquisition, which reduces the influence of physiologic noise and head motion. Single-shot Echo-Volumar Imaging (EVI) has been proposed to address these issues, but requires excessive amounts of encoding for conventional spatial resolutions. We address this by using high acceleration in the two phase encoding directions made possible by a 32-channel receive coil array.  We demonstrate highly-accelerated single-shot EVI with functional studies at 1.5 T. Although susceptibility distortions are larger than those in EPI, the single-shot 3D technique promises increased SNR, vastly improved temporal resolution, and more benign motion effects.

                  2368.     Parallel Imaging Accelerated Multi-Echo FMRI at 7T

Heiko Schmiedeskamp1, Rexford David Newbould1, Roland Bammer1

1Stanford University, Stanford, California , USA

At 7T, EPI suffers from severe image distortions due to off-resonance effects. This is particularly critical for fMRI experiments, where accurate localization of functional activation is desired. Image distortions can be reduced using parallel imaging to R-times undersample k-space, therefore reducing the echo spacing in phase-encoding direction and shorten the EPI readout. The loss in SNR from parallel imaging can be compensated by the acquisition of multiple echo images per excitation pulse. Consequently, parallel imaging leads to greatly reduced image distortions at 7T, while maintaining SNR by multi-echo acquisitions.

                  2369.     Distortion Free, BOLD-Contrast FMRI Using a K-T Accelerated Spin-Echo Based Approach at 7 Tesla
 [Not Available]

Jane Frances Utting1, 2, Uwe Heinrichs1, Sebastian Kozerke2, Roger Luechinger2, Ralph Schnitker1, René Vohn1, Thoralf Niendorf1

1RWTH-Aachen, Aachen, Germany; 2University and ETH Zuerich, Zuerich, Switzerland

In order to maximally exploit the advantages of ultra high magnetic fields for BOLD - fMRI without suffering the gross geometric distortion and signal drop-out intrinsic to echo planar imaging, k-t accelerated displaced UFLARE was performed at 7 Tesla. Activation induced signal changes were measured and mapped, using a functional motor paradigm in normal subjects with and without k-t BLAST factors 2, 5, 8 and 16. The sensitivity to BOLD contrast of k-t accelerated displaced UFLARE is shown to be comparable to that of EPI, promising possibilities such as high resolution fMRI with freely selectable T2 or T2* weighting.

                  2370.     Distortion-Free FMRI in the Orbitofrontal Cortex Using RASER

Ute Goerke1, Ryan Chamberlain1, Essa Yacoub1, Michael Garwood1, Kamil Ugurbil1, 2

1Radiology/University of Minnesota Medical School, Minneapolis, USA; 2Max-Planck-Institute for Biological Cybernetics, Tuebingen, Germany

In fMRI with conventional gradient-echo (GE) EPI, macroscopic magnetic field variations near air-filled cavities result in signal loss and geometric distortions in the images. T2-weighted sequences mitigate such problems. In this paper, a novel T2-weighted sequence, RASER, is applied to fMRI of brain regions, which are challenging to image with GE-EPI. It is demonstrated that activation in the orbitofrontal cortex is fully recovered using RASER.

                  2371.     Statistical Significance of the BOLD Response Probed by RASER

Ute Goerke1, Ryan Chamberlain1, Michael Garwood1, Kamil Ugurbil1, 2

1Radiology/University of Minnesota Medical School, Minneapolis, USA; 2Max-Planck-Institute for Biological Cybernetics, Tuebingen, Germany

T2-weighted fMRI sequences provide advantages with respect to specificity to the site of neuronal activity at ultrahigh magnetic field since they are dominated by signal components originating from the tissue in the capillary bed. However, in conventional implementations, they suffer from inaccurate non-T2 (i.e. T2*) contributions that arise from EPI which is typically used for spatial encoding. In this paper, it is demonstrated that a novel T2-weighted sequence RASER, which eliminates this complication, is able to detect activation as well as the more conventional spin echo-EPI method although its maximal relative signal change is lower.

                  2372.     BOLD FMRI Using T2* Weighted Selective Parity Single Shot 3D GRASE Imaging

Benedikt Andreas Poser1, 2, Matthias Günther3, 4, David Gordon Norris1, 2

1Radboud University, Nijmegen, Netherlands; 2University Duisburg-Essen, Essen, Germany; 3Neurological Clinic, University Hospital Mannheim, University Heidelberg, Germany; 4mediri GmbH, Heidelberg, Germany

A single-shot T2* weighted 3D-GRASE sequence is implemented based on the principles of the recently presented method for selective parity RARE imaging; this removes the CPMG constraint and furthermore reduces the energy deposition by introduction of a variable flip angle scheme. Attractions of the multiply refocused sequence include potentially higher SNR due to 3D excitation, and very high acquisition speed.  Initial functional experiments using visual checkerboard stimulation suggest that brain activation can be detected with high BOLD sensitivity.

                  2373.     Sub-Millimeter Single-Shot 3D GRASE with Inner Volume Selection for T2 Weighted FMRI
                                Applications at 7 Tesla

David A. Feinberg1, Noam Harel2, Sudhir Ramanna1, Kamil Ugurbil2, Essa Yacoub2

1Advanced MRI Technologies, Sebastopol, California , USA; 2Center for Magnetic Resonance Research, Minneapolis, Minnesota, USA

Sub-millimeter resolution fMRI will facilitate probing the human brain for a better understanding of the functional organization of cerebral cortex.  To date, inner-volume segmented 2D SE-EPI has been used for sub-millimeter resolutions at 7T, but limited to single slice acquisitions due to cross-irradiation. A novel sequence, inner volume 3D GRASE is developed for single-shot imaging to obtain multiple slices. Results show 0.5 mm in-plane resolution 3D single-shot fMRI activation maps in human brain similar to 2D maps. The spin echo refocusing minimized less specific large vessel BOLD effects, and enhanced sensitivity to signals from smaller vessels within tissue.

                  2374.     T2 Weighted FMRI Simultaneously Acquired in Two Distinct Areas of the Human Brain at Ultra-High Field

Johannes Ritter1, Pierre-Francois Van de Moortele1, Kamil Ugurbil1

1University of Minnesota, CMRR, Minneapolis, Minnesota, USA

In this study, a Slab wise magnetization Preparation for Functional Imaging with a T2 weight (SPIF-T2) [1] is used. Fifteen oblique slices were positioned to go through the visual- as well as the motor-cortex. This technique is used in conjunction with Parallel Imaging (PI) methods with a one-dimensional reduction factor of four, a half-Fourier technique and a sixteen-channel geometrically adjustable (“flex”) volume coil [2] to allow for whole brain coverage while maintaining short acquisition times, necessary to keep Gradient Echo (GE) contributions small. Specific absorption rate (SAR) is reduced by ~4 fold for 15 slices when compared to a standard multi slice Spin Echo (SE) sequence. This makes it possible to use the more accurate Spin Echo (SE) fMRI (see for instance [1],[3],[4]). Robust activation can be seen in both the visual and motor areas of the brain. This technique can now be applied towards cognitive paradigms corresponding to regions of the brain not previously studied at 7T. 

                2375.     Improved BOLD Detection at 3T Using High-Resolution GRAPPA EPI FMRI

Dionyssios Mintzopoulos1, 2, Loukas G. Astrakas1, Graham C. Wiggins1, Lawrence L. Wald1, Bruce R. Rosen1, A Aria Tzika1

1Massachusetts General Hospital, Boston, Massachusetts, USA

Parallel-imaging (pMRI) enables whole-brain fMRI at increased resolution. pMRI penalties include reduced image SNR and spatially correlated noise; gains include reduced susceptibility artifacts and improved BOLD from higher spatial resolution at optimal TE. We performed a motor fMRI experiment with GRAPPA EPI (factor 3) and with a no-GRAPPA EPI sequence at lower spatial resolution. Detected BOLD values were consistently and significantly higher using GRAPPA versus the no-GRAPPA sequence. Since high spatial resolution is impossible unless severely limiting the FOV and/or increasing TE beyond the optimal range for BOLD detection, we conclude that GRAPPA fMRI benefits may outweigh its disadvantages.

                  2376.     Monitoring Tissue Volume Fraction and T1 Changes During Brain Activation Using a Look-Locker
                                 EPI Sequence

Wanyong Shin1, Hong Gu1, Yihong Yang1

1National Institute on Drug Abuse, NIH, Baltimore, Maryland, USA

We have developed an EPI-based Look-Locker sequence running at a steady-state to monitor physiological and biophysical changes during brain activation. Tissue volume fractions (gray matter, white matter, and cerebral spinal fluid) and T1 were measured every 10 sec, during which a block-design visual stimulation paradigm was presented. Following the stimulation, GM fraction was increased and WM fraction was decreased, while CSF fraction remained the same. T1 was decreased during activation. This new method provides a powerful tool for observing signal changes in tissue components, and would help understand and interpretate fMRI signals.

                  2377.     Turbo Z-Shimmed UNFOLD EPI

Gaohong Wu1, Shi-Jiang Li1

1Medical College of Wisconsin, Milwaukee, USA

Susceptibility differences around the air/bone-tissue boundaries in the human brain induce static field inhomogeneities and result in two major artifacts: image distortion and signal dropout. Most of the studies related to reduction of the susceptibility-induced artifacts attacked one of these two artifacts. An fMRI pulse sequence is proposed to simultaneously reduce both of the artifacts while achieving high spatial coverage with typical imaging parameter settings. The UNFOLD technique and selective z-shim strategy are employed and combined in a framework of the turbo segmented imaging technique. This sequence could be a solution to susceptibility-effect reduction in ultra-high field for fMRI.

                  2378.     Optimizing 3D EPI with K-Space Energy Spectrum Analysis (KESA)

Ming-Long Wu1, Larry Panych1, Nan-Kuei Chen2

1Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; 2Duke University, Durham, North Carolina, USA

In phase-encoded 3D EPI, the k-space energy may shift along the z-direction as a result of local susceptibility field gradients. When the k-space energy is shifted outside of the k-space sampling range, the signal loss artifacts occur. To address this issue, we use the recently developed k-space energy spectrum analysis (KESA) to optimize both acquisition and reconstruction strategies for 3D EPI. The k-space sampling scheme is chosen based on the energy distribution patterns quantified by the KESA. 3D z-shim method is incorporated to further improve the signal-to-noise ratio of the reconstructed 3D EPI.

                  2379.     Asymmetric Spin-Echo Reduces Susceptibility Distortion Without Loss of BOLD CNR

Kimberly D. Brewer1, 2, James Rioux1, 2, Xiaowei Song1, Ryan C.N. D'Arcy1, 2, Chris V. Bowen1, 2, Steven D. Beyea1, 2

1National Research Council of Canada, Halifax, Canada; 2Dalhousie University, Halifax, Canada

Recently the Asymmetric Spin-Echo (ASE) Spiral technique has been proposed for overcoming susceptibility induced field gradients (SFG).  Using a breath-hold task to elicit whole brain activation, we evaluate the use of this sequence for fMRI.  ASE Spiral permits acquisition of up to three spiral images with equivalent R2’-weighting (where R2’ = R2*-R2 and R2 = 1/T2) and k-space filtering (equal to spiral-in). This results in combined images with the reduced image distortion seen in Dual Spiral-In/In, but since all images have matched R2’-weighting, the BOLD CNR is equivalent (or better in regions of SFG) to that of the Dual Spiral-In/Out method.

                  2380.     Single Shot Partial Dual Echo (SPADE) EPI - An Efficient Acquisition Scheme for Whole Brain FMRI

Christian Schwarzbauer1, 2, David Porter3

1MRC Cognition and Brain Sciences Unit, Cambridge, UK; 2University of Cambridge, Cambridge, UK; 3Siemens Medical Solutions, Frimley, UK

SPADE is a new acquisition scheme for fMRI based on dual-echo EPI. As in previous work, additional spin-echo EPI images are used to recover signal in regions of susceptibility-related sensitivity losses in the gradient echo images. However, with SPADE the additional spin-echo images are only acquired for the affected slices in the lower part of the brain, reducing the time required to image each volume. This provides an efficient acquisition scheme for fMRI applications where whole brain coverage (and sensitivity) is required. Our preliminary experimental results demonstrate the feasibility of this approach.

                  2381.     Silent Echoplanar Imaging for Auditory FMRI

Sebastian Schmitter1, Eugen Diesch2, Michael Amann3, Alexander Kroll1, Maurice Moayer2, Lothar Rudi Schad4

1German Cancer Research Center, Heidelberg, Germany; 2Central Institute of Mental Health, Mannheim, Germany; 3University Hospital of Basel, Switzerland; 4University of Heidelberg, Mannheim, Germany

A new low-noise EPI-sequence is presented that is optimized for auditory fMRI measurements. The sequence produces a narrow-band acoustic frequency spectrum by using a sinusoidal readout echo train, which is adapted to the frequency response function of the MR scanner. Compared to a standard EPI-sequence the acoustic noise reduction amounts up to 20 dBA. Statistical parametric mapping of a simple block-design fMRI experiment with a pure-tone stimulus results in higher levels of significance of auditory activation for the low-noise sequence compared to a standard EPI sequence. These findings strongly suggest that the low-noise sequence generates enhanced BOLD contrasts.

 

fMRI: Animal Models

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  2434.     BOLD and Blood Volume-Weighted FMRI of Rat Lumbar Spinal Cord During Non-Noxious and Noxious
                               Hindpaw Stimulation

Fuqiang Zhao1, Mangay Williams1, Xiangjun Meng1, Denise Welsh1, Alexandre Coimbra1, Eric Crown1, Catherine Abbadie1, Jacquelynn Cook1, Mark Urban1, Richard Hargreaves1, Donald Williams1

1Merck Research Laboratories, West Point, Pennsylvania, USA

This study investigates the reproducibility, robustness, and spatial accuracy of fMRI of lumbar spinal cord activation due to transcutaneous noxious and non-noxious electrical stimulation of the hindpaw in á-chloralose anesthetized rats. BOLD and Blood Volume-weighted fMRI data were acquired without and with intravenous injection of USPIO, respectively. Neuronal activation in the spinal cord induced by noxious stimulation can be robustly detected by both fMRI techniques with excellent reproducibility. Spatially, the fMRI signal extended ~5 mm in the longitudinal direction, covering L3-L5 segments. In the cross-sectional direction, the highest signal change of BV-weighted fMRI was in the middle of the ipsilateral dorsal horn, which roughly corresponds to laminae V and VI, while the highest signal change of BOLD fMRI was in the ipsilateral dorsal surface. This study demonstrates that spinal cord fMRI can be performed in anesthetized rats reliably and reproducibly offering it as a potential tool for analgesic drug discovery.

                  2435.     BOLD and Blood Volume-Weighted FMRI of Rat Cervical Spinal Cord with GE and SE EPI

Fuqiang Zhao1, Mangay Williams1, Xiangjun Meng1, Denise Welsh1, Eric Crown1, Alexandre Coimbra1, Catherine Abbadie1, Jacquelynn Cook1, Mark Urban1, Richard Hargreaves1, Donald Williams1

1Merck Research Laboratories, West Point, Pennsylvania, USA

fMRI results of cervical spinal cord with regard to the spatial extension, in both longitudinal and cross-sectional direction, of neuronal activation are inconsistent and inconclusive. Previous cervical spinal cord fMRI experiments were mainly performed using a fast spin echo (RARE) sequence because of it is less sensitive to magnetic field inhomogeneities, but compromising fMRI sensitivity. In this study, we investigate the feasibility of pain fMRI in the cervical spinal cord by BOLD and Blood Volume-weighted fMRI using gradient echo (GE) and spin-echo (SE) EPI in á-chloralose anesthetized rats at 7T In BOLD and BV-weighted fMRI, the largest signal changes occur at the spinal cord segments of C4 to C8 in rostral-caudal direction, and in the ipsilateral dorsal horn in cross-sectional direction. An advantage compared to a RARE sequence is EPI's better temporal resolution allowing acquisition of more data to improve the statistical power of fMRI signal detection.

                  2436.     BOLD FMRI Investigation of Trigeminal Nerve Stimulation at 9.4T

Nathalie Just1, Hanne Frenkel, Rolf Gruetter2

1UNIL,EPFL, Lausanne, Switzerland; 2UNIL,EPFL, University of Geneva, Lausanne, Switzerland

The vibrissal system of the rat is an interesting system to explore structure, function, development and plasticity within the somatosensory cortex because of the functional and morphological correlation between the vibrissae and the barrels. In the present study, single shot EPI gradient echo fMRI of the rat brain at 9.4T was used to map barrel activation during electrical stimulation of the trigeminal nerve. The aim of this study is to establish a reproducible paradigm to measure the BOLD_fMRI response to trigeminal nerve stimulation and determine a relationship between neuronal activity and BOLD changes in the rat somatosensory cerebral cortex.

                  2437.     CBV-Weighted FMRI Study of Neurovascular Coupling in the Caudate Putamen Following Graded
                                Electrical Stimulation in the Forepaw of Rats

Yen-Yu Shih1, 2, You-Yin Chen3, Chiao-Chi Chen2, Bai-Chuang Shyu2, Tiing-Yee Siow2, Zi-Jun Lin2, Jyh-Cheng Chen4, Fu-Shan Jaw1, Chen Chang2

1National Taiwan University, Taipei, Taiwan; 2Academia Sinica, Taipei, Taiwan; 3National Chiao-Tung University, Hsinchu, Taiwan; 4National Yang-Ming University, Taipei, Taiwan

This is the first imaging study that demonstrates the role of caudate putamen in pain-induced neurovascular processing. By evaluating CBV responses following graded electrical stimulation (5 ¡V 60V), salient bilateral vasoconstriction effect was observed specifically in the caudate putamen, while vasodilation only appeared in the contralateral somatosensory cortex.

                  2438.     Mapping Plasticity in the Forepaw Digit Barrel Subfield of Rat Brain Using Functional MRI

Jun-Cheng Weng1, 2, Kai-Hsiang Chuang1, Artem Goloshevsky1, Stephen Dodd1, Jyh-Horng Chen2, Alan P. Koretsky1

1National Institutes of Health, Bethesda, Maryland, USA; 2National Taiwan University, Taipei, Taiwan

This well-defined relationship between the cortical barrels and the forepaw digit makes this system a good model for the study of neuronal function and plasticity. Although the representation of digit columns has been previously investigated by optical imaging of intrinsic signal, mapping this topographically organized representation non-invasively remains challenging. Functional MRI (fMRI) has been shown to map columns in cat visual as well as in rodent whisker barrels. The goal of this study was to test the feasibility of and to optimize fMRI to map the forepaw digit representations in the SI of the rat. Further, this technique was applied for mapping brain plasticity after digit amputation.

                  2439.     Assessment of Functional Cortical Plasticity with BOLD FMRI Mapping of Adjacent Somatosensory
                                 Representations in Rat

Artem G. Goloshevsky1, Stephen J. Dodd1, Alan P. Koretsky1

1National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, USA

Assessment of the reorganizational capacity of adult brain is important for the investigations of the mechanisms of functional cortical plasticity. In this work, a three-dimensional BOLD fMRI mapping of somatosensory limb representations was used to study cortical reorganization in adult rat brain, 2-3 weeks following the peripheral nerve deafferentiation (5 weeks old rats underwent an excision of the sciatic and saphenous nerves in a hindpaw). A sufficient data averaging significantly improved the delineation of the fMRI maps, and the alteration of the map profiles demonstrated an expansion of the forepaw representation into the cortical area corresponding to the hindpaw. Thus, the technique allowed a detailed mapping of the induced plasticity of the cortical somatosensory representations when employed in rats.

                  2440.     Somatotopic Plasticity of the BOLD Response Following Spinal Cord Injury in Rats: Use of Anatomical
                                Landmarks on EPI Images for Accurate Topological Mapping

Esther Gertrud Sydekum1, Christof Baltes1, Arko Ghosh2, Thomas Mueggler1, Martin Schwab2, Markus Rudin2, 3

1University and ETH , Zurich, Switzerland; 2University of Zurich, Switzerland; 3University and ETH, Zurich, Switzerland

Assessment of changes in functional topology of the cortex with fMRI depends on the quality of the reference coordinate system. We have used a highly reproducible artifact caused by the Bregma line on coronal EPI images recorded at 9.4T as geometrical reference to map fMRI data to Paxinos brain atlas. The accuracy of the method was evaluated by analyzing the sensory representation of fore and hind paw derived from BOLD-fMRI using electrical stimulation. As application we studied plastic events in cortical area S1 after spinal cord injury: both the temporal profile and the spatial extent of the response were altered.

                  2441.     Cortical Plasticity of the Brain After Median Nerve Transection Using FMRI at 9.4T by Direct Nerve Stimulation

Seth Reuben Jones1, Rupeng Li1, Chris Pawela1, Daniel L. Shefchik1, Hani Matloub1, Ji-Geng Yan1, Safwan Jaradeh1, James S. Hyde1

1Medical College of Wisconsin, Milwaukee, Wisconsin, USA

A clinical observation provided by our peripheral nerve surgeons is that after transection of a single nerve, in many cases the median nerve, the patient will get partial return of sensory function at the borders between adjacent nerve sensory distributions.  We hypothesize this is a form of brain plasticity and the adjacent nerves will show an expansion of cortical signal with direct nerve stimulation.  In a mulidisciplinary effort we created a rat model that we believe shows plasticity while providing a clinical correlate

                  2442.     Longitudinal FMRI in Rats Following Spinal Cord Lesion and Spontaneous Functional Improvement

Dirk Wiedermann1, Veronica Estrada2, Nicole Brazda2, Anreas Beyrau1, Pedro Ramos-Cabrer3, Hans-Werner Mueller2, Mathias Hoehn1

1Max Planck Institute for Neurological Research, Cologne, Germany; 2Heinrich Heine University, Düsseldorf, Germany; 3Hospital Clínico Universitario, Universidad de Santiago de Compostela, Santiago de Compostela, Spain

After spinal cord injury (SCI) axonal regeneration is impeded, but previous studies have also reported spontaneous regeneration of motor function. Here, we present an investigation on the recovery of the somatosensory system in female rats after SCI using longitudinal fMRI studies.  The main challenge of longitudinal fMRI is a suitable anesthesia.  Therefore we developed an anesthesia protocol for female rats suitable for robust and repetitive fMRI, with a measurement protocol to perform reliable, longitudinal fMRI in SCI and followed up of the spontaneous recovery after SCI with fMRI up to 11 weeks post injury.

                  2443.     Invasion of Whisker Cortical Maps by Adjacent Forepaw Representations Visualized with BOLD FMRI

Benito de Celis Alonso1, Andrew S. Lowe2, John P. Dear3, Kalok C. Lee4, Gerald T. Finnerty5

1King´s College London, London, UK; 2UCL London, UK; 3Imperial College, London, UK; 4King’s College London, UK; 5MRC Centre for Neurodegeneration Research, UK

The adult brain is not hard-wired, but changes with experience. We reported recently that reorganization in adult rodent somatosensory cortex induced by whisker trimming can be visualized with BOLD fMRI. Here, we use BOLD fMRI to ask whether plasticity is restricted to the sensory input that is altered, i.e. the whiskers, or whether other non-deprived sensory maps, e.g. forepaw, reorganize. Our findings indicate that non-traumatic sensory deprivation is sufficient to cause expansion of adjacent representations that are not directly modified by the deprivation protocol. This suggests that cortical representations compete with adjacent representations for cortical space in the normal brain.

                  2444.     11.74T FMRI of Cortical and Subcortical Visual Networks in the Rat

Christopher Bailey1, 2, Basavaraju Sanganahalli1, Alyssa Siefert3, Peter Herman1, Albert Gjedde2, Fahmeed Hyder1

1MRRC, Yale University, New Haven, Connecticut, USA; 2CFIN, Aarhus University, Aarhus, Denmark; 3Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA

Though a predominantly nocturnal animal, the rat has a fully functional visual system. Here we developed methods to probe this sensory system with both high field fMRI and electrophysiological techniques. Our design of stimulus delivery differs from the stroboscopic-based or dark-light adapted systems which generate very robust intensity stimuli. We demonstrate that our stimulus delivery method elicits weak but reproducible brain responses to track hemodynamic and electrophysiological signal changes in cortical and subcortical structures of the rat visual pathway. We demonstrate stimulus frequency-dependent correlations between electrical and BOLD signal changes in the primary visual cortex.

                  2445.     fMRI of Delay and Trace Eyeblink Conditioning in the Visual Cortex of the Rabbit

Michael J. Miller1, 2, Craig Weiss3, Gheorghe Iordanescu2, 3, Xiaomu Song2, 3, John F. Disterhoft3, Alice M. Wyrwicz2, 3

1Northwestern University, Evanston, Illinois, USA; 2Evanston Northwestern Healthcare Research Institute, Evanston, Illinois, USA; 3Northwestern University Feinberg Medical School, Chicago, Illinois, USA

We used fMRI in parallel with delay and trace eyeblink conditioning to image learning-related functional activation within the primary visual cortex (V1).  Our results indicate that these paradigms produce distinct patterns of functional change in V1 with learning.  Trace conditioning produced an expansion of activated area, without any change in maximum BOLD magnitude, whereas the simpler delay paradigm showed an increase in maximum BOLD magnitude but no accompanying change in area.  These differences suggest that the recruitment of additional neurons in V1 is necessary to support the more demanding memory of the trace paradigm.

                  2446.     Post-Oral Nutritive Substances Elicit Brain Activation in Rats

Tomokazu Tsurugizawa1, Takashi Kondoh1, Kunio Torii1

1Ajinomoto Co., Inc., Kawasaki, Japan

Recent studies have shown that post-oral nutritive taste substances are critical in determining preference and appetite for foods. We showed spatio-temporal activation in the higher center of the brain by sweet (glucose), umami (MSG) or salty (NaCl) substances. Subdiaphragmatic total vagotomy (TVX) eliminated the activation by MSG and NaCl. While, glucose was affected little by TVX. These results indicated that post-oral nutritive taste substances activate higher center of the brain via vagal or non-vagal (humoral or spinal) pathway.

                  2447.     Functional Magnetic Imaging of Neural Activity in Rat CNS in Response to Chromatic Stimuli

Christopher Paul Pawela1, Matt C. Mauck1, James Kuchenbecker2, Anthony G. Hudetz1, Jay Neitz1, James S. Hyde1

1Medical College of Wisconsin, Milwaukee, USA; 2Marquette University, Milwaukee, USA

For the first time the response to chromatic stimuli was studied in the visual system of the rodent. This study is an important first step toward developing a CNS model to evaluate the functional consequences of newly introduced therapeutic opsin molecules targeted to either M- or S- photoreceptors.

                  2448.     BOLD FMRI of Sensory Forepaw Stimulation in Mice Using a Cryogenic RF Probe Operating at 400 MHz

Simone Claudia Bosshard1, Christof Baltes1, Thomas Mueggler1, Markus Rudin1

1ETH and University of Zürich, Zürich, Switzerland

The feasibility of BOLD fMRI in mouse after somatosensory forepaw stimulation was investigated using the highly sensitive cryogenic RF transceiver probe. The experiment was performed under isoflurane anesthesia in artificially ventilated and constantly monitored mice. GLM (general linear model) analysis of sequential bilateral forepaw stimulation at 1.5mA and 3Hz showed statistically significant activation in the sensory cortex. BOLD signal changes peaked at 0.85±0.21% on the contralateral and at 0.82±0.23 on the ipsilateral side. This study demonstrates that the use of a cryogenic RF probe provides the high sensitivity required for detection of BOLD changes in small rodents such as mice.

 

phMRI

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  2492.     Cerebral Response to Electrical Stimulation at the Different Anesthetic Intervals: An FMRI Study
 [Not Available]

Xiao-yun Fu1, 2, Tian Yu1, Peng Xie1, 2, Ye Tu1, 3, Su lui2, Huafu Cheng4, Ti-jiang Zhang2, Xiao-Qi Huang2, Qi-yong Gong2, 5

1Zunyi Medical Collge, Zunyi, People's Republic of China; 2Huaxi Hospital,Sichuan University, Chengdu, People's Republic of China; 3 Huaxi Hospital,Sichuan University, Chengdu, People's Republic of China; 4University of Electronic Science and Technology, Chengdu, People's Republic of China; 5University of Liverpool, London, UK

It is still unclear how anesthesia affects such cerebral function during pain processing. Our study aims to investigate functional imaging of brain responses to electrical stimulation in rats at different anesthetic intervals. Our results show that incidence and amplitude of activation in the brain vary across the sequential anesthetic intervals The fuctional MRI can therefore provide further evidence for brain processing of nociceptive stimulation at the various anesthetic intervals. It is likely that increasing incidence and amplitude of activation indicates decreased anesthetic depth. Further study is necessary to clarify the relationship between activation map of brain and anesthetic depth.

                  2493.     A Comparison of Alpha-Chloralose and Propofol as Anaesthetic Regimes for BOLD-FMRI

Nachiket Abhay Nadkarni1, Benito de Celis Alonso2, Jimmy David Bell1

1Hammersmith Hospital, Imperial College London, London, UK; 2Kings College London, London, UK

Most pre-clinical BOLD-fMRI protocols use anaesthesia with the terminal agent alpha-chloralose. This study investigated the use of propofol anaesthesia instead from which recovery is possible- a crucial advantage for many studies. Using a whisker movement stimulation protocol at 9.4 T, we observed a reduced BOLD response under propofol anaesthesia compared to alpha-chloralose (0.49±0.2% vs. 0.91±0.2% signal intensity change, 19.5±8 vs. 130±47 voxels extent size, threshold p<0.05). This reduction agrees with previous observations using propofol for BOLD-fMRI. However, the attenuation of response is an acceptable compromise for studies where recovery is essential.

                  2494.     Levo-Tetrahydropalmatine Modulates Activities in Dopaminergic Circuits of Naïve Rat Brain

Xiping Liu1, Zheng Yang2, Jun Xie1, Qian Yin1, Shi-Jiang Li1

1Medical College of Wisconsin, Milwaukee, USA; 2Beijing Institute of Basic Medical Science, Beijing, People's Republic of China

L- tetrahydropalmatine (l-THP), a D1, D2 receptor antagonist purified from traditional Chinese herb Stephanie [1], has long been used as an analgesic and anti-anxiety agent in China. Recent study has demonstrated that l-THP can significantly attenuate heroin craving and relapse in heroin addicts [2]. Animal behavior experiments also demonstrated this compound can inhibit cocaine’s rewarding effect in terms of self-administration, reinstatement, and brain stimulation reward [3].  Being such a promising treatment for addiction, the baseline action sites and neuronal effect of l-THP, however, have yet to be fully understood.  To further understand neuropharmacological mechanisms of l-THP, here, we employed high-field pharmacological MRI (phMRI) to detect activation induced by acute l-THP administration in naïve rat brain.

                  2495.     Remifentanil-Induced Activation Pattern in Rat Brain Detected with PhMRI and Independent Component Analysis

Wim Otte1, Jan M. van Ree2, Kajo van der Marel1, Annette van der Toorn1, Rick M. Dijkhuizen1

1Image Sciences Institute, Utrecht, Netherlands; 2Rudolf Magnus Institute of Neuroscience, Utrecht, Netherlands

Analysis of phMRI data is often complicated by lack of knowledge about thepharmacological activation model. We have applied a model-freeprobabilistic independent component analysis to assess a pharmacologicalstimulation paradigm in rats that received repetitive injections withincreasing dose of the µ-opioid receptor agonist remifentanil, with orwithout prior administration of its antagonist naloxone. Our analysisdemonstrated significant remifentanil-induced BOLD responses insubcortical regions. The spatial activation pattern was unaffected bynaloxone pretreatment, which blocked the activation responses to the firstlower doses of remifentanil. This model-free analysis demonstrates itspotential for phMRI studies with complex drug adminstration patterns.

                  2496.     CBV FMRI in Conscious Animals Using USPIO: Development of a Tool for Measuring Pharmacodynamic
                                Activity in Drug Development

Denise C. Welsh1, Alexandre Coimbra1, Fuqiang Zhao1, Mangay Williams1, Richard Hargreaves1, Donald S. Williams1

1Merck & Co.,Inc, West Point, Pennsylvania, USA

The ability to assess drug-induced cerebral activity in awake animals allows investigation of neurologic processes under true physiologic conditions, and provides more clinically relevant information during the drug development process.  In conscious animals, we benchmark CBV changes elicited by administration of the carbonic anhydrase inhibitor, acetazolamide(ACZ), and compare it to isoflurane-anesthetized rats.  Improved sensitivity is achieved with USPIO and washout signal changes have successfully been detrended.  ACZ administration produces a greater CBV response in awake animals compared to anesthetized animals. Thus, conducting fMRI in conscious animals may allow for an increased dynamic range to detect small stimulus-induced changes in activity.

                  2497.     Systemic Infection Alters 5-HT Function in the Rodent Brain as Demonstrated by PhMRI

Josephine Raley1, 2, Andrew E. Davis1, Trevor Sharp1, Daniel C. Anthony1, Nicola R. Sibson1

1University of Oxford, Oxford, UK

It is well established that the neurotransmitter 5-hydroxytryptamine (5-HT) is important in key brain functions such as mood regulation, cognition, sleep and pain processing. Furthermore, dysfunction of the 5-HT system has been implicated in the pathophysiology and treatment of a range of psychiatric disorders including major depression. Here we show that activation of 5-HT2A receptors mediates BOLD responses induced by the 5-HT-releasing agent fenfluramine, and that a systemic inflammatory response can markedly alter 5HT function in the brain. Our findings strongly support a role for peripheral infection in the pathogenesis of mood disorders associated with the 5-HT system.

                  2498.     Early Life Stress Impairs Serotonergic Neurotransmission Specifically in the Prefrontal Cortex Revealed by
                                Pharmacological FMRI in Mice

Florence Razoux*1, Holger Russig*1, Thomas Mueggler1, Christof Baltes1, Isabelle M. Mansuy1, Markus Rudin1, 2

1University & ETH Zurich, Zurich, Switzerland; 2University Zurich, Zurich, Switzerland

Early life stress is a risk factor of depression. We are investigating the role of serotonergic neurotransmission in this transition using fMRI in a mouse model of early life stress (MSUS) by analyzing changes in cerebral blood volume (CBV) after injection of a 5HT1A receptor agonist. In MSUS and control mice, a decrease in CBV was detected in regions with 5-HT1A receptor expression. The decrease in the prefrontal cortex was significantly lower in MSUS than in control mice. Cross-correlation of 30 brain areas further identified subcortical structures with large differences in inter-regional correlation between the MSUS and control mice.

                  2499.     Changes in BOLD Signaling Induced by Local Chemical Activation of the Dorsal Midbrain in Rats

Jason Berwick1, Aneurin Kennerley1, Christopher Martin1, Myles Jones1, Luke Boorman1, Ying Zheng1, John Mayhew1, Peter Redgrave1

1University of Sheffield, Sheffield, UK

In human brain imaging studies, it is rarely possible to explore the consequences of direct manipulations of relevant circuitry.   The purpose of the present study was, therefore, to establish technology and procedures for measuring the effects of direct, local chemical stimulation of the brain with fMRI.  Using an established model of subcortical visual processing the present study demonstrated that regional changes in neural responses to light stimuli evoked by local chemical stimulation of the midbrain superior colliculus can be measured with fMRI.

                  2500.     Mechanisms of a Negative BOLD Response to Acute Cocaine Administration in Rat Brain

Junfang Xian1, 2, Gaohong Wu2, Qian Yin2, Zhilin Wu2, Chunming Xie2, Xiping Liu2, Shi-Jiang Li2

1Beijing Tongren Hospital, Capital Medical University, Beijing, People's Republic of China; 2Medical College of Wisconsin, Milwaukee, USA

The negative BOLD responses after systemic administration of cocaine have been reported, but the detailed mechanisms remain unclear.  We observed significant negative BOLD signals, large vessel dilation in the rat brain and significant MABP decrease after cocaine administration during the transient period of the negative BOLD signal.  Further, a significant correlation existed between the changes in the negative BOLD and the changes in the vessel size.  In conclusion, our results demonstrated that the transient negative BOLD signals could result from cocaine-induced dilation of large vessel in the rat brain observed by using high-resolution fMRI study at high field strength

 

Spine & Bone

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  2525.     Decay from Diffusion in Internal Field (DDIF) and R2* Contrast in Bovine Tibiae Samples at 3 T and 7 T

Eric Edward Sigmund1, Edward X. Guo2, Yi-Qiao Song3

1New York University, New York, New York, USA; 2Columbia University, New York, New York, USA; 3Schlumberger-Doll Research, Cambridge, Massachusetts, USA

An in vitro study of 8 mm bovine tibiae trabecular bone (TB) samples was conducted as part of an implementation on clinical scanners of a recently developed TB structural contrast, based on decay due to diffusion in the internal field (DDIF).  Both DDIF and R2* contrast were measured in 10 samples, varying in strength by a factor of 10, as a function of field strength (3 T vs. 7 T) and field angle relative to the bone axis.  Both contrasts show sensitivity to scale and anisotropy information., and provide valuable data for the  optimization of DDIF for in vivo imaging.

                 2526.     MR Imaging at 3T of Trabecular Bone Structure InType 2 Diabetes Patients: Comparison with
                                In-Vivo Micro-CT

Markus B. Huber1, Ben Hyun1, Roland Krug1, Umesh Masharani1, Sharmila Majumdar1, Thomas M. Link1

1University of California, San Francisco, San Francisco, USA

Type 2 diabetes patients have elevated bone mineral density (BMD) but an increased risk of fracture of the e.g. hip. To assess the differences in bone quality, we performed high resolution MRI at 3T of the calcaneus, the distal tibia and the distal radius and in-vivo micro-CT imaging of diabetes patients and a age- and BMI-matched control group. We found differences in the trabecular bone structure between the two groups which were very site dependant. We conclude that the general model for fracture risk prediction might not be accurate for type 2 diabetes patients

                  2527.     In Vivo Trabecular Bone Micro-Imaging at Isotropic Resolution Using 3D FLASE with Parallel Imaging at 3T

Jeremy F. Magland1, Michael J. Wald1, Rostislav Lemdiasov2, Felix W. Wehrli1

1University of Pennsylvania Medical Center, Philadelphia, Pennsylvania, USA; 2InsightMRI, LLC., Worcestor, Massachusetts, USA

A modified 3D FLASE pulse sequence tailored for micro-imaging at 3T field strength is shown to be able to generate images in vivo of trabecular bone with 160 µm3 isotropic voxel size at the distal tibia. Unlike past studies that involve highly anisotropic acquisitions (anisotropy factor of 3 or more), the present methodology provides detailed insight into the plate-rod architecture of the trabecular network in all three dimensions. The higher resolution, acquired in 16 minutes scan time, was achieved with a custom-built 4-element phased array in conjunction with partial parallel imaging.

                  2528.     Image Resolution and SNR in 2D Radial Ultrashort TE Imaging

Mark Bydder1, Jiang Du1, Atsushi Takahashi2, Matthew D. Robson3, Graeme Bydder1

1University of California, San Diego, California , USA; 2GE Healthcare, Menlo Park, California , USA; 3Oxford University, UK

The optimal SNR in radial imaging is obtained with a short readout duration.  However this also limits the attainable resolution. Various trade-offs of SNR and resolution are considered.

                  2529.     Clinical Evaluation of the Compact MRI System for Trabecular Bone Microstructure Measurements
                                of the Finger

Katsumi Kose1, Nachiko Iita1, Shinya Handa1, Kazuki Ohya1, Tomoyuki Haishi2, Masako Ito3

1University of Tsukuba, Tsukuba, Japan; 2MRTechnology Inc., Tsukuba, Japan; 3Nagasaki University, Nagasaki, Japan

A compact MRI system developed for trabecular bone (TB) microstructure measurements was applied to 51 normal subjects and 230 patients to evaluate its clinical efficacy. 3D MR images with 180 microns x 180 microns x 160 microns spatial resolution of 46 normal subjects and 119 patients were successfully acquired with negligible motion blur and used to calculate bone microstructure parameters. The obtained results have suggested that the structure model index (SMI) is the most sensitive parameter to characterize the pathological status of the TB.

                  2530.     Evaluation of the Detection Sensitivity of Simulated Trabecular Bone Loss in μMRI

Charles Qingchuan Li1, Jeremy F. Magland1, Chamith S. Rajapakse1, X Edward Guo2, Xiaohui Henry Zhang2, Felix W. Wehrli1

1University of Pennsylvania, Philadelphia, Pennsylvania, USA; 2Columbia University, New York City, New York, USA

Patients suffering from osteoporosis or other osteodegenerative diseases experience loss of trabecular bone mass and structural integrity, leading to a decrease in the overall mechanical strength of the bone. The development of the “virtual bone biopsy” (VBB), a combination of magnetic resonance micro-imaging (μMRI) and digital image processing techniques, has been shown to quantify topology and scale of human trabecular bone noninvasively. Through digital simulation of trabecular bone loss at resolutions and SNR levels typically achievable in clinical μMRI, it is shown that VBB processing techniques are capable of quantifying structural changes caused by two different forms of bone loss.

                  2531.     Optimized Partial Parallel Imaging of Trabecular Bone Microstructure in the Distal Tibia

Michael J. Wald1, Jeremy Magland1, Felix W. Wehrli1

1University of Pennsylvania Medical Center, Philadelphia, Pennsylvania, USA

Micro-MRI of trabecular bone requires high resolutions leading to long scan times.  At higher fields, the gain in signal to noise can be traded for shorter scan times using partial-parallel imaging.  Noise inflation and reconstruction artifacts of partial-parallel imaging can adversely affect the derived structural parameters.  In this work, a generalized partial-parallel acquisition (GRAPPA) with multi-column multi-line interpolation (MCMLI) is optimized for the fast large angle spin echo (FLASE) pulse sequence in the distal tibia at 3T for an approximate two-fold acceleration.  The optimal acquisition and reconstruction are evaluated using an empirical approach to measuring the signal to noise performance and through measuring the derived structural parameters in both the accelerated and non-accelerated acquisitions.

                  2532.     Magnetic Resonance Microscopy of Collagen Mineralization

Ingrid E. Chesnick1, Jeffrey T. Mason1, Naomi Eidelman2, Kimberlee Potter1

1Armed Forces Institute of Pathology Annex, Rockville, Maryland, USA; 2National Institute of Standards & Technology, Gaithersburg, Maryland, USA

A model mineralizing system was subjected to magnetic resonance microscopy (MRM), to study how water proton relaxation times and magnetization transfer ratios (MTR) can be used to monitor the replacement of water around collagen fibrils with mineral. Our model system was mineralized with polymer-stabilized amorphous calcium carbonate. X-ray diffraction data and MRM-derived parameter maps established that the mineralization process can be sub-divided into 3 phases: (i) water displacement by amorphous calcium carbonate, (ii) mineral accretion, and (iii) collagen encapsulation. Our results support the use of MTR as a surrogate measure of collagen mineralization.

                  2533.     Magnetic Resonance Microscopy of a Novel Mineralizing System

Ingrid E. Chesnick1, Francis A. Avallone2, Kimberlee Potter1

1Armed Forces Institute of Pathology Annex, Rockville, Maryland, USA; 2Armed Forces Institute of Pathology, Washington, District Of Columbia, USA

We present a novel mineralizing system in which a polymer scaffold is seeded with osteoblasts isolated from chick calvarial bones and the scaffold is implanted onto the allantochorial membrane of a developing chick embryo. Seven days post-implantation there was a notable reduction in the water proton T2 values and a marked increase in water proton MTR values compared to non-implanted controls. These results were attributed to the generation of bone-like tissue within the polymer scaffold, which was later confirmed by fluorescence microscopy. This novel model system can be used to gain further insights into the bone formation process in vivo.

                  2534.     T2*-Relaxometry and 1H-MRS at 3T Applied to Healthy and Osteoporotic Subjects: Preliminary Data
                                Supporting a New Procedure to Evaluate Bone Fracture Risk

Silvia Capuani1, 2, Mauro Rebuzzi3, Fabrizio Fasano4, 5, Gisela E. Hagberg4, 6, Marco Di Mario4, Vincenzo Vinicola4, Bruno Maraviglia, 67

1CNR-INFM CRS SOFT, Rome, Italy; 2Enrico Fermi Center, Rome, Italy; 3Physics Dpt Univ. "La Sapienza", Italy; 4IRCCS Santa Lucia Foundation, Rome, Italy; 5CNR-INFM CRS SOFT, Italy; 6Enrico Fermi Center, Italy; 7Univ. "La Sapienza", Rome, Italy

Bone Mineral Density (BMD) accounts only for 60% of the global risk of bone fracture due to the partial information that BMD provides on bone tissue. Other components, such as bone marrow, constitutes principally by lipids and water, are present in spongy bone, and may contribute in determining its resistance to fracture. We evaluated T2* as function of both lipids-water content (from 1H-spectra) and trabecular bone density in calcanei of healthy and osteoporotic subjects to investigate the individual variability which affects T2* measurements. The goal is optimize the  procedure based on spongy bone T2*-measurements, to be used in clinical practice.

                  2535.     Magnetic Resonance Imaging in Murine Spondyloarthropathy: A Longitudinal Study

Marleen Verhoye1, 2, Peggy Jacques3, Dirk Elewaut3, Eric Achten4, Nadja Van Camp1, Annemie Van der Linden1

1Bio-Imaging Lab, University of Antwerp, Antwerp, Belgium; 2Vision Lab, University of Antwerp, Belgium; 3Lab. for Molecular Immunology and Inflammation, Dept. of Rheumatology, Ghent University Hospital, Ghent, Belgium; 4Department of Neurology, Department of Radiology and Medical Imaging, Ghent University Hospital, Ghent, Belgium

In vivo longitudinal MRI was used to evaluate the sacroiliac joints in relation to disease duration in a TNF-ÄARE mouse model of SpA. During the course of the disease, MRI demonstrated that the sacroiliac joints become gradually affected. Joint space narrowing can be very well appreciated on T1-weighted images, eventually leading to joint bridging. Furthermore, as compared to controls, both sacrum and iliac bones remain very poorly mineralized (demonstrated by T2-weighted MRI) until 7 months of age. We conclude that in addition to an inflammatory syndrome strongly resembling SpA, chronic TNF exposure also has detrimental effects on normal bone mineralization.

                  2536.     Spinal Versus Whole Body MRI in Patients with Multiple Myeloma and Monoclonal Gammopathy of
                                Undetermined Significance

Tobias Baeuerle1, Kerstin Fechtner, Jens Hillengass, Hans-Ulrich Kauczor, Hartmut Goldschmidt, Lars Grenacher, Stefan Delorme

1German Cancer Research Center, Heidelberg, Germany

The aim of our study was to evaluate if a spinal MRI is sufficient for evaluation of patients with newly diagnosed multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS) or if a whole body MRI is necessary to detect all focal lesions. In 100 patients with MM and MGUS the majority of focal lesions was detected in the extra-axial skeleton which would not have been seen in spinal MRI only. Although spinal MRI is the standard examination in these patients, whole body MRI is needed for detection of focal lesions in patients with newly diagnosed MM and MGUS.

                  2537.     Reproducibility of a Novel 3D Pulse Sequence for Mapping T in Inter-Vertebral Disc

Matthew Fenty1, Walter Witschey1, Chenyang Wang1, Ravinder Reddy, PhD1, John Bruce Kneeland, MD2, Arijitt Borthakur, PhD1

1University of Pennsylvania, Philadelphia, Pennsylvania, USA; 2Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA

We measured the reproducibility of mapping T with a novel 3D MRI pulse sequence called SLIPS, which is based on the steady-state free precession. We are now able to generate 3D biochemical maps of tissue hydration and proteoglycan content in the discs of the entire lumbar spine in vivo in less than 15 minutes.  The total mean coefficient of variation for the study was 10%.

                  2538.     Quantitative Assessment of Normal and Degenerative Intervertebral Discs Using Apparent Diffusion
                                Coefficient with GRAPPA
 [Not Available]

Eito Kozawa1, Waka Mizukoshi2, Youichi Sato2, Naoko Nishi2, Fumiko Kimura2

1Saitama Medical University, 1397-1, Yamane, Hidaka-shi, Japan; 2Saitama Medical University, Japan

We examined 62 subjects with 1.5-T MR imaging units on b factors of 0, 400, and 800 msec of diffusion-weighted images. We divided our subjects into two groups, those normal intervertebral disc and those degenerative intervertebral disc, and we  compared the apparent diffusion coefficients (ADC) in the two group. The ADCs of the groups were significantly different according to Mann-Whitney’s U test (P < 0.01).   In conclusion, a statistically significant decreased in the ADC values of degenerated lumbar disc compared with the ADC values of normal disc.

                  2539.     Bone Structural Analysis on Different Resolutions in Magnetic Resonance Imaging

June-Goo Lee1, 2, Gyunggoo Cho1, Youngkyu Song1, Jee-Hyun Cho1, Jong Hyo Kim2

1Korea Basic Science Institute, Cheongwon, Republic of Korea; 2Seoul National University College of Medicine, Seoul, Republic of Korea

It is known that trabecular bone structure gives additional information to bone mineral density (BMD) in the prediction of bone strength in vitro and in the discrimination of patients with without osteoporotic vertebral and femur fractures. The trabecular bone structure has been studied using MR images. But for in vitro MR imaging, the resolution of the image is limited by scan time. Thus, we developed bone structural analysis program and investigated the effect of different resolutions of magnetic resonance image on the calculation of trabecular bone parameters

 

Renal

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  2599.     Magnetic Resonance Detection of Kidney Iron Deposition in Sickle Cell Disease: A Marker of Chronic
                                Hemolysis

Aaron Schein1, 2, Cathleen Enriquez2, Thomas D. Coates2, John Wood2

1Keck School of Medicine, Los Angeles, California , USA; 2Children's Hospital Los Angeles, Los Angeles, California , USA

T2* signal, which decreases near tissue iron deposits, serves as a surrogate for tissue iron in magnetic resonance images (MRI). We found that R2* (1000/T2*) signal increased linearly in the kidneys of sickle cell disease (SCD) patients with the hemolytic marker lactate dehydrogenase, demonstrating here that chronic hemolysis is coupled to renal hemosiderosis. Kidney iron load, unlike in the heart and liver, was not related to chronic blood transfusions. Though prospective studies are needed, renal R2* as a noninvasive biomarker of chronic hemolysis in SCD patients may correlate with other hemolytic sequelae such as pulmonary hypertension and systemic vasculopathies.

                  2600.     Evaluation of Venous Extension in Renal Cell Carcinoma Using a 2D Fat-Saturated Steady State Free
                                Precession Sequence

David W. Stanley1, Christine U. Lee2, James F. Glockner2

1GE Healthcare, Rochester, Minnesota, USA; 2Mayo Clinic, Rochester, Minnesota, USA

Evaluation of abdominal-pelvic venous disease with MRI is widely accepted.  Conventional contrast-enhanced 2D and 3D SPGR sequences are very accurate in detecting venous thrombus; however, given growing concerns regarding the use of gadolinium-based contrast media in patients with renal dysfunction, non-contrast techniques have become increasingly important.  We investigated venous staging of 14 patients with renal cell carcinoma using an overlapping fat-saturated steady state free precession sequence, and compared the results with a more traditional contrast-enhanced 3D SPGR sequence.

                  2601.     Quantification and Validation of Kidney Perfusion Imaging in the Cortex and Medulla with DCE-MRI Using
                                a Blood Pool Contrast Agent in a Swine Model

Lutz Lüdemann1, Benno Nafz1, Franz Elsner1, Michael Meißler1, Nicola Kaufels1, Christian Große-Siestrup1, Pontus Persson1, Matthias Gutberlet2, Philipp Lengsfeld3, Matthias Voth3

1Charité, Berlin, Germany; 2Universitätsklinik Leipzig, Leipzig, Germany; 3Bayer Schering Pharma AG, Berlin, Germany

The aim of this animal study was to show the feasibility of quantification of total as well as cortical and medullary renal perfusion with DCE-MRI using an approved blood pool agent. A total of 18 female pigs were investigated. A modified ultrasound transit time flow probe was used o measure absolute renal blood flow and compared with blood flow determined by DCE-MRI. The kidney blood flow measured by ultrasound highly correlated with the total kidney perfusion determined by DCE-MRI, P<0.001. Cortical and medullary flow were also highly correlated with the degree of flow reduction, P<0.001. The DCE-MRI technique presented allows absolute quantification of total kidney perfusion as well as separate determination of cortical and medullary flow.

                  2602.     Improvement of Functional MRI Measurement with Automatic Movement Correction in Native and
                               Transplanted Kidneys

Baudouin Denis de Senneville1, Iosif Mendichovszky2, Sébastien Roujol1, 3, Isky Gordon2, Chrit Moonen1, Nicolas Grenier4

1CNRS, Bordeaux, France; 2UCL Institute of Child Health, London, UK; 3Ecole Nationale Supérieure d’Electronique, Informatique et Radiocommunications de Bordeaux, Bordeaux, France; 4Groupe Hospitalier Pellegrin, Bordeaux, France

Non-invasive and accurate measurement of renal perfusion and glomerular filtration rate (GFR) could have a major impact on understanding renal physiopathology and for serial monitoring of the course of many acute and chronic kidney diseases. Dynamic contrast-enhanced magnetic resonance imaging can now be used for the evaluation of these functional parameters. This study describes a suitable method for 2D correction of kidney motion during the passage of the bolus of contrast with subpixel accuracy. The Patlak-Rutland model was used to calculate GFR in the kidney cortex on a voxel-by-voxel basis.

                  2603.     Influence of Oxygen and Carbogen Breathing on Renal Oxygenation Measured by BOLD- Imaging
                                 at 3.0 Tesla

Andreas Boss1, Petros Martirosian, Margit Jehs, Cristina Rossi, Klaus Dietz, Claus D. Claussen, Fritz Schick

1University Hospital of Tübingen, Tübingen, Germany

The aim of the present study was to assess whether carbogen (95% O2, 5% CO2) or pure oxygen breathing can influence renal oxygenation. Changes in the renal tissue oxygenation were measured using blood oxygenation level dependent (BOLD) magnetic resonance imaging. It was demonstrated in this study, that renal tissue oxygenation may be influenced with carbogen or oxygen breathing. The changes can be assessed with T2*-weighted MRI at high field strength. The effects are in the expected range for the BOLD effect of 3-4% at 3.0 Tesla.

                  2604.     Renal Blood Oxygen Level Dependent (BOLD) Magnetic Resonance Imaging in a Rodent Model
                                of Hypertension Mediated End Organ Damage

Stephen C. Lenhard1, Amy Grill1, karpagam Aravindhan1, Ross Bentley1, Kristeen Maniscalco1, Chris P. Doe1, Robert N. Willette1, Beat Michael Jucker1

1GlaxoSmithKline, King of Prussia, Pennsylvania, USA

Changes in the renal BOLD MRI signal can be interpreted as changes in tissue pO2 in hypoxic environments such as the renal medulla and possibly cortex.  In this study, we have implemented BOLD MRI in the renin dTg (double transgenic overexpressing both human angiotensinogen and human renin) rat model of hypertension to characterize changes in renal tissue oxygenation during the progression of renal dysfunction.  Additional relationships between medullary and cortical BOLD signal with urine microalbumin excretion was examined.

                  2605.     Importance of T1-Correction in T1-Weighted MR Renal Perfusion Measurements

Christian Kremser1, Mohamed Abd Ellah1, Leo Pallwein-Prettner1, Christian Wolf1, Ferdinand Frauscher1, Georg Bartsch1, Werner Jaschke1, Michael Schocke1

1Innsbruck Medical University, Innsbruck, Austria

To obtain reliable renal perfusion values from dynamic contrast enhanced MRI, signal calibration has to be performed to avoid errors due to non-linear signal behavior. It was the purpose of this study to demonstrate how the omission of signal calibration may influence the results and conclusions of clinical studies.

                  2606.     3D Respiratory Triggered T2-Weighted Imaging of the Kidneys with 3D-FSE-Cube

Jonathan William Currie1, Reed F. Busse, Thomas Winter1, Anja C. Brau, Philip J. Beatty, Jean H. Brittain, Scott B. Reeder

1University of Wisconsin, Madison, Wisconsin, USA

T2 weighted FSE imaging of the kidneys, renal collecting system and ureters provides excellent contrast for evaluation of cystic renal neoplasms as well as other urological abnormalities, and is an important component of a complete evaluation of the kidneys.  However, 2D methods are limited by partial volume averaging effects.  MR evaluation of the kidneys would greatly benefit from 3-dimensional imaging and improved spatial resolution.  3D-FSE-Cube is a volumetric technique that provides high quality near isotropic resolution imaging of solid abdominal organs such as the kidneys.  The purpose of this work is to demonstrate 3D FSE T2 weighted imaging of the kidneys using 3D-FSE-Cube.

                  2607.     23Na MRI of In Vivo Rat Kidneys at 3.0 T: Preliminary Experience

Pottumarthi Vara Prasad1, Alexander Ivanishev2, Robert Greenman2, Lu Ping Li1, Ying Wu1, Joann Carbray1, Jeffrey Stainsby3, Andres Carrillo4, Robert E. Lenkinski2

1Evanston Northwestern Healthcare, Evanston, Illinois, USA; 2Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; 3GE Healthcare, Toronto, Canada; 4GE Healthcare, Evanston, Illinois, USA

In vivo 23Na MRI has shown to be useful for functional evaluation of the kidneys.   We present our preliminary experience in implementing 23Na MRI on a clinical whole body 3.0 T scanner equipped with multinuclear capability.  Using custom developed quadrature transmit/receive volume coil we have demonstrated feasibility of obtaining 23Na MRI of in vivo rat kidneys.  In combination with standard proton extremity coil, position matched high resolution proton images were obtained with relative ease.  Data demonstrating acute spatio-temporal changes in sodium concentration following administration of furosemide are also presented.

                  2608.     Optimization of the Determination of the Corticomedullary Sodium Gradient from Na-23 Images
                                 of the Human Kidney

Robert E. Lenkinski1, Yael Rosen1, Ananth Madhuranthakam2, Alex Ivanishev1

1Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; 2GE Healthcare, Boston, Massachusetts, USA

We have evaluated a combination of an acquisition weighted pulse sequence and Fermi filtering to determine the sodium concentration gradient in a phantom. We found that it was possible to improve the SNR by a factor of 1.7 while preserving the ability to determine the sodium concentration gradient. We also applied this approach to data obtained on a human kidney and found similar results

                  2609.     The Influence of Tissue Composition on Signal to Noise Ratio of MR Measurements

Zhengyu Yang1, Tuhin Kumar Sinha1, John C. Gore1

1vanderbilt institute of imaging science, nashville, Tennessee, USA

All MRI image contain some spatial variance of signal because of the presence of additive random noise. However, at high spatial resolution some of this variance may reflect not only thermal noise  (temporal variance, which averages incoherently as more images are acquired) but also microscopic inhomogeneities in tissue composition (spatial variance),which comes from variations in tissue composition. We have developed methods to quantify and examine the nature of these spatial variances in MR images. The ultimate goal of this research is to determine how these systematic variances correlate with the underlying macro-molecular composition of tissues.

 

Hyperpolarized Gas Lung MRI

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                   2643.     Sequence Considerations for 2D Radial MRI of Hyperpolarized Gases

Jim M. Wild1

1University of Sheffield, Sheffield, UK

Radial MRI of hyperpolarized (HP) 3He gas has shown to be effective in imaging ventilation dynamics in the human lungs. With angular undersamping, the number of views, can be reduced in favour of increased temporal resolution, provided the streak artifacts (spatially correlated noise) can be tolerated. In this work, factors effecting the SNR, spatial resolution and streak prevalence in undersampled short TE spoiled radial imaging are considered for HP gas MRI. Simulations of the effect of gradient diffusion dephasing and RF undersampling for constant and variable flip angle radial schemes are presented and compared with experiments in gas phantoms and human lungs with HP 3He.

                  2644.     Rapid Three-Dimensional Hyperpolarized 3He Imaging of the Lung Using an Optimized Steady-State
                               Free-Precession Pulse Sequence: Increased SNR Without Off-Resonance Banding Artifacts

John P. Mugler, III1, G Wilson Miller1, Talissa A. Altes, 12, Jaime F. Mata1, Eduard E. de Lange1, William A. Tobias3, Gordon D. Cates, Jr1, 3, James R. Brookeman1

1University of Virginia School of Medicine, Charlottesville, Virginia , USA; 2Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA; 3University of Virginia, Charlottesville, Virginia , USA

This work describes an optimized implementation of a 3D-SSFP pulse sequence for ventilation imaging of the lung using hyperpolarized helium-3. By using a TR less than 2 ms, this optimized technique suppresses intensity banding artifacts that were seen with earlier 2D implementations of SSFP imaging.  In addition, the 3D-SSFP sequence yields 3-4 times higher SNR than widely-used low-flip-angle spoiled-GRE methods, and thus requires a much lower dose of hyperpolarized gas than a comparable spoiled-GRE acquisition. High-quality reconstructions in any image plane are obtained in an acquisition time of less than 10 s.

                  2645.     Airway Measurement in 3D Using Dynamic Hyperpolarized He-3 Multi-Echo VIPR

Eric T. Peterson1, James H. Holmes1, Sean B. Fain1

1University of Wisconsin - Madison, Madison, Wisconsin, USA

A high temporal resolution VIPR (3D PR) acquisition using hyperpolarized helium-3 was combined with a multi-step airway measurement algorithm combining airway segmentation, calculation of the centerline axis, lung airway measurement of diameter and branch angle. The high temporal resolution and high contrast of the acquisition allows for similar measurement of airways to the 3rd generation with values within 25% of those measured with multi-detector CT. Results approach the quality of commercially available CT airway segmentation packages for the large airways.

                  2646.     Diffusion Tensor Imaging of the Rat Lung Using Hyperpolarized 3He

Timothy Mark Taves1, 2, Alexei V. Ouriadov1, Giles Edmund Santyr1, 2

1Robarts Research Institute, London, Canada; 2University of Western Ontario, London, Canada

Gas diffusion anisotropy and magnitude information may be valuable in the specification of lung disease. Diffusion Tenor Imaging (DTI) provides full diffusion information.  DTI of a capillary phantom and a rat lung was performed using hyperpolarized 3He.  Diffusion ellipsoid maps were reconstructed to verify that the gas diffuses predominantly along the capillaries and airways as expected.  Trace maps of the lungs were also reconstructed to show that the magnitude of diffusion is greatest in the upper airways as expected.

                  2647.     Three Dimensional Imaging of Ventilation Dynamics in Asthmatics Using HYPR ME-VIPR

James H. Holmes1, Rafael L. O'Halloran1, Eric T. Peterson1, Ethan K. Brodsky1, Janet E. Kuhlman1, Nizar N. Jarjour1, Sean B. Fain1

1University of Wisconsin-Madison, Madison, Wisconsin, USA

The use of a multi-echo vastly undersampled isotropic projection acquisition (ME-VIPR) is used to accelerate data acquisition in hyperpolarized (HP) He-3 lung imaging of asthma patients. This technique coupled with a HYPR reconstruction allowed 3D dynamic lung imaging. Further, this technique can retrospectively accommodate lost patient breath-holds to maximize image quality. Imaging results are quantified using the percent ventilated volume and validated with spirometry and MDCT. Further, detection of differential filling is shown.

                  2648.     Simulation of Temporal Resolution for Non-Cartesian K-Space Sampling Strategies to Trace Fast Dynamic
                               Changes of Helium-3 Spin Density

Maxim Terekhov1, Julien Rivoire1, Wolfgang Schreiber1

1Mainz University Medical School, Mainz, Germany

The increase of the temporal resolution is for many years one of the issues in dynamic MRI -imaging of lung ventilation with hyperpolarized gases.  One of the ways known to solve this problem is the use of non-cartesian schemes of k-space sampling (radial or spiral). However, the artefacts originated from the sophisticated image reconstruction schemes of these methods makes unclear their real timing efficiency. Additional complications also come from using of the “sliding-window” technique. To examine the time resolving effectiveness of different sampling strategies under conditions of dynamic imaging, the numerical simulations were done.  The generated initial spin density matrix was affected by the temporal modulation of intensity. Different interleaving strategies were tested to provide the closest tracing of spin density modulation function with intensity of reconstructed images.

                  2649.     Validation of Regional Compliance Measurement Using Hyperpolarized 3He MRI in a Syringe Lung
                                 Phantom

Vahid Vadhat1, Kiarash Emami1, John MacDuffie Woodburn1, Robert V. Cadman1, Jiangsheng Yu1, Hans Hyonchang Kim1, Masaru Ishii, 12, Rahim R. Rizi1

1University of Pennsylvania, Philadelphia, Pennsylvania, USA; 2Johns Hopkins University, Baltimore, Maryland, USA

A phantom study was performed for preliminary validation of a regional compliance measurement technique using dynamic ventilation method. Using this measurement technique, the fractional ventilation value, in a 10-mL glass syringe simulating a single lung voxel was obtained. The validity of the fractional ventilation value through direct measurement is used to calculate compliance and was tested by comparing it to the theoretical value.

                 2650.     The Role of Collateral Pathways in Long-Range 3He Diffusion  [Not Available]

Jason C. Woods1, Seth-Emil Bartel1, Susan E. Haywood1, Yulin V. Chang2, Dmitriy A. Yablonskiy1, David S. Gierada1, Mark S. Conradi1

1Washington University, St Louis, Missouri, USA; 2Children's Hospital of Pennsylvania, Philadelphia, Pennsylvania, USA

In order to determine the role of collateral routes in measurements of the long-range 3He diffusion coefficient (LRDC), we simulated LRDC in a human lung with no collateral pathways, made closed-form calculations in a simple lung model, and measured LRDC in human lungs and porcine lungs (with little collateral ventilation).  The robustly-tested simulations resulted in an LRDC 20 times lower than measured in human lungs; calculations revealed that a surprisingly small number of holes through alveolar walls can increase LRDC to measured values, and LRDC in porcine lungs was 4x smaller than in humans, confirming the role of collateral pathways in health.

                  2651.     A Theory of Diffusion Time Dependence of ADC in Hyperpolarized 3He Lung MRI. Millisecond Range

Alexander L. Sukstanskii1, Dmitriy A. Yablonskiy1

1Washington University, St. Louis, USA

Lung diffusion MRI with hyperpolarized 3He gas provides information on lung structure and function. Substantial increases in ADC have been reported in emphysema suggesting that 3He gas ADC could serve as a biomarker for disease progression. However, even in healthy human lungs ADC exhibits rather broad variability, with different studies reporting results between 0.15 cm2/s and 0.25 cm2/s. Here we provide a theoretical analysis demonstrating a significant diffusion time dependence of ADC, even for diffusion times on the order of several milliseconds, which can explain the observed ADC variability. 

                  2652.     Anatomical Trends in Coregistered ADC and T2* Maps of 3He Gas in the Lungs of Healthy Normals

Salma Ajraoui1, Rob Ireland1, Kuan J. Lee1, Neil Woodhouse1, Jim M. Wild1

1University of Sheffield, Sheffield, UK

Measurement of the 3He gas ADC with pulsed gradient methods can be used to infer spatial dimensions at the alveolar level, and a gradient in the 3He ADC in the anterior-posterior direction has previously been reported in healthy normals. The 3He T2* is a second parameter which will depend upon the alveolar dimensions as these define the microscopic susceptibility gradients in which the gas is diffusing. Field strength, macroscopic B0 field homogeneity, adjacent blood perfusion (microscopic susceptibility difference) and degree of gas diffusion will also play a role in T2*. In previous work at 1.5T the 3He T2* was found to increase with lung volume (inflation of the alveoli). In this work 3He ADC and T2* data was collected from spatially registered 2D slices in four volunteers and the spatial trends within the lungs of the two parameters was investigated.

                  2653.     Diffusion Weighted ³He-MRI in the Assessment of Pulmonary Emphysema: A Regional Evaluation
 [Not Available]

Klaus Kurt Gast1, Christa Gast1, Trine Stavngaard2, Jim M. Wild3, Lise Vejby Soegaard4, Joerg Schmiedeskamp5, Christoph Dueber1, Wolfgang Guenter Schreiber1, Hans-Ulrich Kauczor6, Edwin JR van Beek7, Claus Peter Heussel8

1Johannes Gutenberg University Hospital, Mainz, Germany; 2Rigshospitalet Copenhagen University Hospital, Copenhagen, Denmark; 3University of Sheffield, Sheffield, UK; 4Hvidovre University Hospital, Hvidovre, Denmark; 5Max Planck Institute for Polymer Research, Mainz, Germany; 6German Cancer Research Center, Heidelberg, Germany; 7Carver College of Medicine, University of Iowa Hospitals and Clinics, Iowa City, USA; 8Thoraxklinik Heidelberg, Heidelberg, Germany

Although the utility of diffusion weighted ³He-MRI in pulmonary emphysema has been shown, correlation to HR-CT was limited. A possible reason for this discrepancy may be related to regional inhomogeneity of the disease. In this regional evaluation, correlation between ADClocal and MLDlocal was r=0.24 in COPD, r=0.71 in alpha-1-antitrypsin deficiency and r=0.48 in healthy volunteers. Local hyperinflation with collapse of neighbouring alveoli, overlying infections and perfusion inhomogeneity are possible explanations for the methods’ unequivocal results. It is postulated that diffusion weighted ³He-MRI shows the function of a lung area while CT provides morphologic information with possible influence of concomittant disease.

                  2654.     Lung Function Decline Over 5 Years as Measured by the Hyperpolarized Helium-3 ADC in Smokers

Talissa A. Altes1, 2, Chengbo Wang1, Michael Salerno3, Eduard E. de Lange2, Kai Ruppert1, 2, John P. Mugler, III2

1Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA; 2University of Virginia, Charlottesville, Virginia , USA; 3Duke University, North Carolina, USA

Six subjects at risk for or with mild COPD underwent hyperpolarized helium-3 diffusion MRI and spirometry on two occasions separated by 5.4 to 6.7 years.  The average percent change in mean ADC, FEV1 %predicted and FEV1/FVC was 10%, 5% and -11%, respectively. The average rate of decline was 0.031cm2/s/yr for mean ADC, and 23mL/yr for FEV1. There was a strong correlation between mean ADC at baseline and percent change in mean ADC, FEV1, and FEV1/FVC (r = -0.83, -0.86, and -0.92, respectively), suggesting that elevated baseline mean ADC values are associated with a more rapid decline in lung function. 

                  2655.     Assessment of Longitudinal Changes of Lung Function and Structure Pre– and Post– Lung Volume
                                Reduction Surgery in a Rat Elastase Model of Emphysema

Masaru Ishii1, 2, Kiarash Emami2, Jianliang Zhu2, John MacDuffie Woodburn2, Stephen Kadlecek2, Michael E. Friscia2, Jiangsheng Yu2, Hans Hyonchang Kim2, Joseph B. Sharger2, Warren B. Gefter2, Rahim R. Rizi2

1Johns Hopkins University, Baltimore, Maryland, USA; 2University of Pennsylvania, Philadelphia, Pennsylvania, USA

Lung volume reduction surgery (LVRS) is used to improve respiratory mechanics in severe forms of emphysema. Proper patient selection schemes still remain unclear. We show using hyperpolarized helium MRI measures of lung function and microstructure and a longitudinal cohort study that LVRS’s improvement in function is a macroscopic phenomena and that it is applicable to subjects with homogenous forms of emphysema.

                  2656.     Assessment of Peripheral Airways Development After Preterm Birth by Hyperpolarised 3He

Marius Ovidiu Mada1, John R. Owers-Bradley1, Manjith Narayanan2, Mike Silverman2, Jau-Yi Wang1, Caroline S. Beardsmore2

1University of Nottingham, Nottingham, UK; 2University of Leicester, Leicester, UK

Premature born children suffer from altered lung development and function. We compared (in vivo) measurements of acinar structure in children born preterm with healthy controls using the techniques of hyperpolarised 3He MR (HPHe3MR) and Multiple Breath Nitrogen Washout (MBNW). When compared to controls, children born preterm have a trend towards differences in spirometry but have markedly higher ventilatory inhomogeneity in their acinar airways. Lung damage at the alveolar level normally leads to higher ADC as the gas can diffuse more freely so we hypothesised that ADC would be higher in children born preterm. The lack of a difference between preterm and control groups suggests that the acinar changes are not related to abnormal structure at the alveolar level. The ADC sometimes exhibits an inhomogeneous distribution across the lungs, more commonly in girls. Extending the study to children of other age groups could clarify whether this inhomogeneity is related to puberty.

                  2657.     Diffusion Time: A Tuning Parameter for Lung Airspace Size Selection with Hyperpolarized 3He
                               Gas Diffusivity Measurements?

Dattesh D. Shanbhag1, Talissa A. Altes2, Jack Knight-Scott3

1GE Global Research, Bangalore, India; 2The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA; 3Children's HealthCare of Atlanta, Atlanta, Georgia, USA

The diffusion signal attenuation, in restricted environments of lung airspaces is function of the effective observation time or diffusion time (δ) and the diffusion gradient area. If the latter is fixed, then δ can be possibly used to traverse different geometrical structures. In present work, we investigated the effects of variable δ on diffusion measurements of 3He gas in vivo in lungs. In all volunteers (N = 3), it was noticed that rms displacements (indicative of airspace sizes) increased in quadratic manner with increasing δ. No asymptotic value was reached, suggesting diffusion in lung airspaces is hindered, not restricted.

                  2658.     Reliability Evaluation of Hyperpolarized 3He Gas Diffusion Models in Lungs in Vivo: Wide Range
                                 B-Value Space

Dattesh D. Shanbhag1, Talissa A. Altes2, Jack Knight-Scott3

1GE Global Research, Bangalore, India; 2The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA; 3Children's HealthCare of Atlanta, Atlanta, Georgia, USA

The study was aimed to evaluate the reliability and failure modes of various models currently used to obtain information about lung microstructure in vivo using hyperpolarized 3He gas diffusion as probe. The models were tested for wide range of b-values from 0.2 s/cm2 to 52 s/cm2 in 14 healthy volunteers and 3 COPD patients. A critical cutoff b-value of 20 s/cm2 was identified, which separated the performance of most models in two regions.  1.b < 20 s/cm2 : Greater differences observed between healthy volunteers and COPD patients 2.b > 20 s/cm2 increased confidence for diffusion measurements  albeit with reduced sensitivity.

                  2659.     Effect of Finite Gradient Width on Hyperpolarized 3He Gas Lung Q-Space Diffusion Spectroscopy in Vivo

Dattesh D. Shanbhag1, Talissa A. Altes2, Jack Knight-Scott3

1GE Global Research, Bangalore, India; 2The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA; 3Children's HealthCare of Atlanta, Atlanta, Georgia, USA

Q-space diffusion formalism assumes SGP condition, which is violated on clinical scanners due to the finite rise time of gradient systems. In this work, we examined effects of diffusion gradient width (δ) on q-space parameters and its implication on measurements of lung airspaces in healthy volunteers and COPD patient. As the δ increased, it was noticed that the displacement probability profile became narrower, with concomitant decrease in rms displacement. On an average, the rms displacements decreased by 11-15% for a change in δ by 1 ms. We conclude that on clinical systems, the measured lung airspace sizes are typically under-estimated.

                  2660.     S/V Measurements in a 3He Bead Phantom Using a Short-Time-Scale NMR Diffusion Sequence

Michael Carl1, G Wilson Miller1, John Paul Mugler III1, William Al Tobias1, Gordon Dell Cates1

1University of Virginia, Charlottesville, Virginia , USA

We used a specialized short-time-scale diffusion NMR technique to measure S/V. The pulse sequence is based on a technique introduced by our group last year and involves concatenating a large number of bipolar diffusion-sensitizing gradients to increase the diffusion attenuation of the MR signal while maintaining a fundamentally short diffusion time. Periodic refocusing RF pulses were added to the sequence to extend the signal duration in more hostile environments with short T2*. The features of this technique are explored using Monte-Carlo simulations of gas diffusion in various geometries and experimental diffusion measurements in a bead phantom containing 3He gas.

                  2661.     Posture Dependent Effects on Human Pulmonary Oxygen Partial Pressure

Rachel Nora Scheidegger1, 2, Dan Chonde, 12, Leo Lee Tsai, 23, Matthew Scott Rosen1, 4, Samuel Patz, 35, Ross William Mair1, Ronald Lee Walsworth1, 4

1Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA; 2Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts, USA; 3Harvard Medical School, Boston, Massachusetts, USA; 4Harvard University, Cambridge, Massachusetts, USA; 5Brigham and Women's Hospital, Boston, Massachusetts, USA

The lung is exquisitely sensitive to gravity and posture, yet current imaging systems restrict subjects to horizontal positions only. Our open-access human MRI system permits the study of pulmonary function with subjects in a variety of postures.  Using this system, we have studied human pAO2 in subjects in both vertical and supine positions.  Our results show clear gradients in pAO2 from the top to bottom of the lung, in agreement with the “zones of the lung” model of West. The standard deviation of pAO2 values when vertical was higher than that when horizontal (11.6 torr vs. 6.4 torr, respectively).

                  2662.     Multi-Slice PO2-Weighted 3He Imaging in a Rabbit Model of Regionally Impaired Perfusion

G. Wilson Miller1, Ugur Bozlar1, Jaime F. Mata1, Colleen M. Schamber1, John P. Mugler III1, Gordon D. Cates1, Klaus D. Hagspiel1

1University of Virginia, Charlottesville, USA

PO2-weighted 3He MRI was performed in a rabbit model of reversible pulmonary embolus. The goal was to observe PO2-weighted contrast, rather than obtain quantitative measurements of absolute PO2, allowing multiple 2D slices to be acquired in the same breath hold without concern that inter-slice gas diffusion would corrupt the PO2 measurement. Images clearly showed regions of elevated PO2 corresponding to the location of obstructed perfusion. These lesions resolved when perfusion was restored.

                  2663.     Measurement of Pulmonary Partial Pressure of Oxygen and Oxygen Depletion Rate with Hyperpolarized
                                Helium-3 MRI: A Preliminary Reproducibility Study on Pig Model

Jiangsheng Yu1, Sheeva Rajaei1, Michelle Law1, Masaru Ishii, 12, Stephen Kadlecek1, Kiarash Emami1, Vahid Vadhat1, John MacDuffie Woodburn1, Richard A. Guyer1, Hans Hyonchang Kim1, Warren Gefter1, Rahim R. Rizi1

1University of Pennsylvania, Philadelphia, Pennsylvania, USA; 2Johns Hopkins University, Baltimore, Maryland, USA

Pulmonary partial pressure of oxygen (pO2) and oxygen depletion rate (R) are two important parameters of lung function. This work presents a preliminary reproducibility study on a pig model. In the in-vivo animal experiments, four normal Yorkshire pigs were scanned. The global statistical analyses show that average variation of global mean is 9.7% for pO2 and 28.9% for R, and that the average variation of percentiles (10th, 25th, 50th, 75th and 90th) and inter-quartile range is 15.0% for pO2 and 34.9% for R. The region-of-interest analysis on the manually-selected regions shows that the average variation of mean is 11.3% for pO2 and 23.4% for R.

                  2664.     A New Acquisition Scheme for Simultaneous Measurement of Fractional Ventilation, Apparent Diffusion
                               Coefficient  and Partial Pressure of Oxygen

Jiangsheng Yu1, Stephen Kadlecek1, Kiarash Emami1, Masaru Ishii, 12, Vahid Vadhat1, John MacDuffie Woodburn1, Michelle Law1, Richard A. Guyer1, Hans Hyonchang Kim1, Warren Gefter1, Rahim R. Rizi1

1University of Pennsylvania, Philadelphia, Pennsylvania, USA; 2Johns Hopkins University, Baltimore, Maryland, USA

In this work, we present a new acquisition scheme for simultaneously measuring fractional ventilation, apparent diffusion coefficient (ADC) and partial pressure of oxygen (pO2) with hyperpolarized 3He MRI. The new acquisition scheme consists of two parts. The first part is a typical ventilation sequence, in which several breaths of 3He gas are used for fractional ventilation measurement; at the end of the last inhalation of 3He, the breath is held for a single acquisition measurement of ADC and pO2. The ventilation measurement ends with a high concentration of 3He gas in the lung, which yields a high signal-to-noise ratio for ADC and pO2 measurement. We demonstrated this technique on an in-vivo rabbit experiment.

                  2665.     High Resolution Measurement of Regional Alveolar Partial Pressure of Oxygen in the Mouse Lung by
                                Hyperpolarized 3He MRI

Kiarash Emami1, John MacDuffie Woodburn1, Richard A. Guyer1, Stephen Pickup1, Stephen Kadlecek1, Masaru Ishii, 12, Robert V. Cadman1, Jiangsheng Yu1, Hans Hyonchang Kim1, Michael Stephen1, Warren B. Gefter1, Rahim R. Rizi1

1University of Pennsylvania, Philadelphia, Pennsylvania, USA; 2Johns Hopkins University, Baltimore, Maryland, USA

An implementation of a technique for measurement of regional alveolar partial pressure of oxygen in the mouse lung with an unprecedented resolution using hyperpolarized 3He MRI is demonstrated.

                  2666.     High Resolution Measurement of Regional Ventilation in the Mouse Lung by Hyperpolarized 3He MRI

Kiarash Emami1, John MacDuffie Woodburn1, Richard A. Guyer1, Stephen Pickup1, Stephen Kadlecek1, Masaru Ishii, 12, Robert V. Cadman1, Jiangsheng Yu1, Hans Hyonchang Kim1, Michael Stephen1, Warren B. Gefter1, Rahim R. Rizi1

1University of Pennsylvania, Philadelphia, Pennsylvania, USA; 2Johns Hopkins University, Baltimore, Maryland, USA

An implementation of a technique for high-resolution measurement of regional ventilation in the mouse lung using hyperpolarized 3He MRI is demonstrated and results are compared to an earlier technique.

                  2667.     Measurement of Regional Ventilation in Large Animals by Hyperpolarized 3He MRI: One Step Closer
                                  to Human Studies

Kiarash Emami1, Stephen Kadlecek1, John MacDuffie Woodburn1, Jiangsheng Yu1, Vahid Vadhat1, Masaru Ishii, 12, Robert V. Cadman1, Hans Hyonchang Kim1, Michael Stephen1, Warren B. Gefter1, Rahim R. Rizi1

1University of Pennsylvania, Philadelphia, Pennsylvania, USA; 2Johns Hopkins University, Baltimore, Maryland, USA

A new method to measure regional ventilation using hyperpolarized 3He MRI is proposed and its application in large animals is demonstrated. Small quantities of helium-3 gas and much shorter acquisition time compared to earlier methods promotes imminent implementation of this noninvasive technique in humans.

                  2668.     Hyperpolarized Helium-3 Ventilation Imaging Under Spontaneous Breathing Conditions in Mice

Hasan ALSAID1, Elise Bannier1, Vasile Stupar1, Katarzyna Cies´lar1, Sophie Gaillard1, Emmanuelle Canet-Soulas1, Yannick Crémillieux1

1Université Lyon1, Creatis-LRMN, CNRS, UMR 5220, U630 INSERM, ESCPE,, Villeurbanne, France

Hyperpolarized 3He ventilation imaging studies in mice have been performed using either animal tracheotomy or intubation protocols combined with assisted ventilation. These approaches are invasive and traumatic for animals and might not be suited for multiple, longitudinal assessments of animal lung function. Recently, Hyperpolarized 3He ventilation imaging was demonstrated in rabbits and rats under free breathing conditions. This approach is more challenging in mice because of small lung tidal volume and high respiratory rates. In this work, we developed and applied a non-invasive imaging protocol based on retrospective radial Cine imaging and sliding window technique under spontaneous mouse breathing conditions.

                  2669.     Hyperpolarized 3He MR Imaging of Ventilation After Bacterial Lipopolysaccharide Exposure in Mice:
                                A Model for Image-Guided Sampling of Ventilation Defects

Abraham Thomas1, 2, James Voltz2, Boma Fubara1, Darryl Zeldin2, Bastiaan Driehuys1

1Duke University Medical Center, Durham, North Carolina, USA; 2National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA

Hyperpolarized 3He MRI is a powerful tool for visualizing ventilation defects in human subjects with asthma. Though ventilation defects have many postulated causes, their etiology is often unclear. To directly probe the origins of ventilation defects we utilized a lipopolysaccharide(LPS) instillation mouse model. LPS inhalation has been associated with the development of asthma and severity of the disease. In this study we created high-resolution 3He MR images to reveal defects associated with LPS-instillation and then used these images to specifically guide tissue sampling.  We found that ventilation defects are dose-dependent and occur within 2 hours of LPS dosing.

                  2670.     3He MR Ventilation Imaging Under Spontaneous Breathing Condition in a Rodent Model of Broncho-
                                Constriction Induced by Serotonin

Karim Mosbah1, Vasile Stupar1, Yves Berthezène1, Nicolau Beckmann2, Yannick Crémillieux1

1Université Lyon 1, Lyon, France; 2Novartis Institutes for BioMedical Research, Basel, Switzerland

The purpose of this work is to assess in spontaneously breathing rats the bronchoconstriction induced by serotonin using a hyperpolarized 3He MR ventilation protocole.the SA (signal amplitude) and MSDR (maximum signal decay rate) parameters representing respectively the tidal volume and the expiratory gas rate were derived from dynamics image series.The findings of this study reflect the expected effects of the serotonin injection (decrease of the expiratory flow associated with a decrease of the tidal volume).

                  2671.     1H and HP 3He MR Imaging of LPS Treated Mice

Lars E. Olsson1, Per Ola Önnervik2, Amir Smailagic2, Paul D. Hockings1

1AstraZeneca, Mölndal, Sweden; 2AstraZeneca, Lund, Sweden

The lungs of mice were examined 48 hours after LPS treatment using both 1H and hyperpolarized 3He MR imaging. Lesions on 3He images were characterized by ventilation defects. Correspondingly, lesions on 1H images were edema. The ventilation defects were often larger than the corresponding edema. The functional data provided by 3He add new information about the inflammation but in this study the imaging methods were equally sensitive.

                  2672.     Hyperpolarized 3He Magnetic Resonance Imaging of Cystic Fibrosis :Initial Findings in Adults with 
                              Moderate and Good Lung Function and Comparison to Spirometry
 [Not Available]

Yara Hosein1, Lindsay Mathew1, Andrew Wheatley1, Giles Edward Santyr1, Nigel Angus Morgan Paterson2, Grace Parraga1

1Robarts Research Institute, London, Canada; 2The University of Western Ontario, London, Canada

The overarching goal of this study is to identify new imaging intermediate endpoints of cystic fibrosis (CF) and then validate these as outcome measures for CF clinical trials.  A number of new CF therapies are in development and feasible, sensitive, specific and precise measurements are now urgently required.  While lung function parameters typically have been used as the primary endpoints in therapy development studies, the specific improvement in lung function in patients with CF (as a result of mucolytic therapy) has rendered these measurements less sensitive to potential effects of novel therapies.  Therefore, the aim of this observational pilot study was to assess the precision and specificity of candidate intermediate endpoints of CF measured using hyperpolarized helium-3 (3He) magnetic resonance imaging (MRI).  Accordingly we are assessing the measurement reproducibility of 3He MRI phenotypes in adults with CF and the relationship of MRI-derived CF lung phenotypes to established measurements of lung function.

                  2673.     Ventilation and Heterogeneity in Mild-To-Moderate and Severe Asthmatics Using Hyperpolarized 3He MRI

Yanping Sun1, Sanaz Zhalehdoust Sani2, Haihua Bao1, Yang-Sheng Tzeng1, Joey Mansour1, Jessica Gereige1, Xiangzhi Zhou1, Lindsey R. Madison1, Michael Hyosang Cho1, Elliot Israel1, Kenneth Lutchen2, Mitchell S. Albert1, 3

1Brigham and Women's Hospital, Boston, Massachusetts, USA; 2Boston University, Boston, Massachusetts, USA; 3University of Massachusetts Medical School, Worcester, Massachusetts, USA

Hyperpolarized 3He MRI was performed to investigate the ventilation heterogeneity response of mild-to-moderate and severe asthmatics, compared to healthy subjects at baseline,  Methacholine(Mch) challenge, deep inspirations(DI), and Albuterol administration. Mch challenge produced a ventilation heterogeneity score change from baseline that was largest in the healthy subjects, smaller in the mild-to-moderate asthmatics, and least in the severe asthmatics. The healthy subjects and mild-to-moderate asthmatics showed a recovery of the heterogeneity score following DIs, suggesting a bronchodilation effect, while the severe asthmatics had impaired bronchodilation. Albuterol was shown to reverse the induced heterogeneity from Mch in both healthy subjects and asthmatics.

                  2674.     A Method of Regional Assessment of Lung Structure and Function Using MDCT and Helium-3 MRI

Eric T. Peterson1, Guillermo Gonzalez-Fernandez1, Sean B. Fain1

1University of Wisconsin - Madison, Madison, Wisconsin, USA

A high temporal resolution VIPR (3D PR) acquisition using hyperpolarized helium-3 was combined with a multi-step airway measurement algorithm combining airway segmentation, calculation of the centerline axis, lung airway measurement of diameter and branch angle. The high temporal resolution and high contrast of the acquisition allows for similar measurement of airways to the 3rd generation with values within 25% of those measured with multi-detector CT. Results approach the quality of commercially available CT airway segmentation packages for the large airways.

                  2675.     Administration Unit for ³He

Manuela Güldner1, Stefan Becker2, Andreas Friesenecker2, Klaus K. Gast3, Werner Heil1, Ernst Wilhelm Otten1, Alexander Scholz4, Wolfgang Schreiber3

1Institut für Physik, Mainz, Germany; 2ic-automation, Mainz, Germany; 3Klinik und Poliklinik für Radiologie, Mainz, Germany; 4Anästhesie, Mainz, Germany

An administration unit for hyperpolarized noble (HP) gases is presented which fulfills the safety requirements given by the Medical Devices Law. This device allows to administer gas boli (accuracy: ÄV / V < 3%) in a pre-defined time during the inspiration cycle. It enables to use gas mixtures and can be equipped with an on-line polarimeter to monitor the HP gas polarization.

                  2676.     Effect of Reduced Pressure on the Polarization of 129Xe in the Production of Hyperpolarized 129Xe Gas:
                                 Development of a Simple Continuous Flow Mode Hyperpolarizing System Working at Pressures as
                                 Low as 0.15 Atm

Hirohiko Imai1, Junko Fukutomi1, Atsuomi Kimura1, Hideaki Fujiwara1

1Osaka University, Suita, Japan

The effect of reduced pressure on the polarization of 129Xe has been examined in batch and continuous flow modes to produce hyperpolarized 129Xe in a simple way. The polarization of 129Xe was enhanced by reducing the total gas pressure down to near 0.1 atm in both modes, being enhanced to about twice of that observed near atmospheric pressure. Also, the stability of polarization in the continuous production of hyperpolarized 129Xe was sufficiently established in different flow rates. The technique developed in the present work is expected to provide a simple and handy type of 129Xe hyperpolarizing system.

                  2677.     Impact of a Simulated Pulmonary Embolism in a Rabbit Model as Detected by XTC MRI

Kai Ruppert1, 2, Jaime F. Mata2, Talissa Altes1, 2, Ugur Bozlar2, James R. Brookeman2, Klaus D. Hagspiel2, John P. Mugler III2

1The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA; 2University of Virginia, Charlottesville, Virginia , USA

Previous studies have demonstrated the feasibility of indirectly detecting a pulmonary embolism (PE) using hyperpolarized helium-3 MRI. In this work we investigated whether Xenon polarization Transfer Contrast (XTC) MRI can detect changes in pulmonary blood volume, and whether this method is sensitive enough to detect the impact of a simulated PE in a rabbit model. Our findings indicate that XTC MRI, despite being insensitive to perfusion, permits the observation of the regional redistribution of the pulmonary blood volume secondary to the PE.

                  2678.     Detection of Interstitial Lung Disease in Humans with Hyperpolarized 129Xe

Samuel Patz1, James P. Butler2, Iga Muradyan1, Mirko I. Hrovat3, Hiroto Hatabu1, Paul F. Dellaripa, Isabel M. Dregely4, Iulian Ruset4, F. William Hersman4

1Brigham and Women's Hospital, Boston, Massachusetts, USA; 2Harvard School of Public Health, Boston, Massachusetts, USA; 3Mirtech, Inc, Brockton, Massachusetts, USA; 4University of New Hampshire, Durham, New Hampshire, USA

Quantitation of the diffusion of hyperpolarized 129Xe from alveolar gas spaces to septal tissue allows one to measure functional pulmonary parameters. Here we demonstrate the ability to measure increased septal thickness in subjects with mild to moderate interstitial lung disease.

                  2679.     High-Resolution Chemical Shift Imaging of the Lungs with Xe-129 During a Single 6 Second Breath-Hold:
                                Results from a Rabbit Model of Pulmonary Embolism

Jaime Mata1, Ugur Bolzar1, Kai Ruppert2, 3, Klaus Hagspiel1, Talissa Altes2, 3, Anthony Soltis1, Wilson Miller1, William Tobias1, Gordon Cates1, James Brookeman1, John Mugler III1

1University of Virginia, Charlottesville, USA; 2University of Pennsylvania, Philadelphia, USA; 3Children's Hospital of Philadelphia, USA

Previous implementations of Chemical Shift Imaging (CSI) of the lung with hyperpolarized xenon-129 (hpXe-129) required imaging for 8minutes, which is not practical for application in humans. We developed an optimized version of CSI that yields images of hpXe-129 with high in-plane spatial-resolution during a single breath-hold.  We report the evaluation of this technique using a rabbit model of pulmonary embolism.  From the CSI data we directly calculate images reflecting the amount of Xe-129 in the airspaces, and dissolved in the lung tissue and blood, and thus obtain spatial information regarding how Xe-129 is distributed in the different compartments, providing regional information about lung physiology.

                  2680.     Detecting Simulated Pulmonary Embolism in a Rabbit Model with Hyperpolarized Xenon-129 Uptake
                                Spectroscopy

Yulin Chang1, Jaime F. Mata2, Ugur Bozlar2, Talissa Altes1, 2, James R. Brookeman2, Klaus D. Hagspiel2, John P. Mugler III2, Kai Ruppert1, 2

1The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA; 2University of Virginia, Charlottesville, Virginia , USA

Previous studies have demonstrated the feasibility of indirectly detecting a pulmonary embolism (PE) using hyperpolarized helium-3 MRI. In this work we investigated whether hyperpolarized Xenon-129 uptake spectroscopy can detect global changes in the xenon uptake dynamics for a simulated PE in a rabbit model. Although the uptake parameters in animals with and without PE differed considerably, the variability of the responses in the individual rabbits was also remarkably high and might indicate the impact of difficult to reproduce systemic responses.

                  2681.     Simulations of the Hyperpolarized 129Xe SSFP and SPGR Pulse Sequence Signal Response

Martin H. Deppe1, Jim M. Wild1

1University of Sheffield, Sheffield, UK

Imaging hyperpolarized (HP) 129Xe in the gas phase is the basis for promising techniques to assess lung function such as XTC, but suffers from an intrinsically lower SNR compared to HP 3He MRI owing to the lower gyromagnetic ratio. Typically, spoiled gradient echo (SPGR) sequences are used, but recently steady-state free precession (SSFP) sequences have attracted interest for imaging hyperpolarized agents, as the transverse magnetization can be recycled by balanced gradients, resulting in higher SNR. In this preliminary work we show computations for in vivo HP 129Xe MRI that suggest an SNR improvement by a factor of 3.2 by using an optimized SSFP sequence instead of a bandwidth matched optimized SPGR sequence.

 

Bowel Imaging

Hall D                                   Monday 14:00-16:00   

                   2707.     Rapid 3D T1-Mapping of Inflamed Bowel in Crohn’s Disease at 3.0 T

Karin Horsthuis1, Aart J. Nederveen1, Marijn-Willem de Feiter1, Pieter CF Stokkers1, Cristina Lavini1, Jaap Stoker1

1Academic Medical Center, Amsterdam, Netherlands

The purpose of our study was to determine the feasibility and value of T1-mapping in abdominal MRI as an objective, quantifiable, and reproducible means of determining disease activity in luminal Crohn’s disease. For 9 patients we acquired T1-maps before and after administration of intravenous Gadolinium (Gd). Subsequently Gd-concentrations were calculated. We found a good correlation between Gd-concentration in inflamed bowel and CRP-values. Mean Gd -concentrations were higher in patients with moderate to severe disease than in patients with mild disease. It is feasible to perform T1-mapping of the abdomen and results are encouraging.

                  2708.     Effect of a 5-HT3 Antagonist on Small Bowel Water Content

Luca Marciani1, Steve Foley1, Caroline L. Hoad1, Eugene Campbell1, John J. Totman1, Eleanor F. Cox1, Alexander Armstrong1, Paul Manby1, Robin C. Spiller1, Penny A. Gowland1

1University of Nottingham, Nottingham, UK

Recent developments in MRI allow non-invasive, patient-acceptable monitoring of small bowel water content. In this placebo controlled, double-blind, randomised, 2-way cross-over study we aimed to assess the effect of a 5-HT3 antagonist (Ondansetron) on small bowel water content in healthy volunteers. 16 subjects were administered placebo or Ondansetron. We found that Ondansetron markedly increased fasting small bowel water content. This may reflect reduction in fasting small bowel migrating motor complex frequency. MRI has potential important clinical application in understanding the role of 5-HT3 antagonists in controlling small bowel water content and transit, and how these mediate gastrointestinal symptoms in IBS-D.

                  2709.     Validating the Potential of 1H MRS in Assessing the Effects of Dietary Fatty Acids on the Modulation of
                                Inflammation in an Animal Model of Inflammatory Bowel Disease (IBD)

Sonal Varma1, 2, Ranjana Bird3, Michael Eskin2, Brion Dolenko1, Jayadev Raju3, Tedros Bezabeh1, 2

1National Research Council Institute for Biodiagnostics, Winnipeg, Canada; 2University of Manitoba, Winnipeg, Canada; 3University of Waterloo, Waterloo, Canada

1H MRS has been shown to be a sensitive tool for the study of colonic inflammation in inflammatory bowel disease (IBD). IBD can progress to colon cancer and this risk increases with the duration of disease. The effects of various dietary agents on colon cancer have been studied; however, knowledge of their effects on IBD and its sequential progression to cancer is very limited. Our study suggests that 1H MRS can accurately assess the effect of dietary fatty acids on inflammation in IBD and may be a suitable tool for chronological studies on IBD and its progression to colon cancer.

                  2710.     In Vivo Detection of Early Colorectal Tumors in Mice Using Contrast-Enhanced Magnetic Resonance
                                 Imaging

Devkumar Mustafi Mustafi1, Urszula Dougherty1, Marc Bissonnette1, Xiaobing Fan1, Marta Zamora1, Gregory S. Karczmar1

1The University of Chicago, Chicago, USA

A novel class of MRI contrast agents containing VO2+-chelated organic ligands has been developed that provide excellent T1 and T2* contrasts in high-resolution MR images of rodent tumors. We have demonstrated that these contrast agents are taken up by cancer cells which are highly glycolytic. These results provide the basis for in vivo MRI studies for early detection of colorectal tumors in mice. Results from in vivo MRI studies in a clinically relevant model demonstrate that small colorectal tumors of ~ 1 mm in size can be detected and MR images can be correlated with in vitro histological images.

                  2711.     T2- And Perfusion-Based MRI Assessment of Colon Wall and Mesenteric Inflammation in the Rat

Andreas Pohlmann1, Lorna Tilling1, Hervé Barjat1, Huw D. Lewis1, Kevin Lee1, Michael F. James1

1GlaxoSmithKline R&D Ltd, Harlow, UK

The TNBS rat model induces marked colon wall thickening and mesenteric inflammation reflecting human inflammatory bowel disease (IBD) and hence providing an opportunity to evaluate potential new treatments. We developed a methodology (T2w, contrast-enhanced T1w) for repeated MRI at 4.7T. Principal component analysis (PCA) applied to the T1w image time series highlighted colon wall and mesenteric inflammation, with the combined cross-sectional area increasing on average by 800% (TNBS-treated vs naïve). Actual T1 changes and gut motion artefacts were distinguished based on the normalized standard deviation. This technique showed a marked effect of a gold standard drug for IBD.

                  2712.     Gadofluorine M Enhanced MR Imaging of Inflammatory Bowel Disease: Quantitative Analysis and
                               Histologic Correlation in a Rat Model
 [Not Available]

Bernd B. Frericks1, Jörg C. Hoffmann1, 2, Birgit Hotz1, Steffi Valdeig1, Bernd Misselwitz3, Karl-Jürgen Wolf1, Frank K. Wacker1, 4

1Charité, Campus Benjamin Franklin, Berlin, Germany; 2St. Marienkrankenhaus, Ludwigshafen, Germany; 3Bayer Schering Pharma, Berlin, Germany; 4Johns Hopkins Hospital, Baltimore, USA

Aim of the study was to analyze the enhancement-pattern of Gadofluorine M in the colonic wall of rats with inflammatory bowel disease (IBD), induced by transrectal DNBS application. T1w-SE-images at 2.4T were acquired before and immediately, and 5, 15, 45, 60, and 90 min after i.v.-application of Gadofluorine M. Signal intensities within the colon wall, S/N- and ER-ratios were obtained. Inflammation was assessed histologically. Based on the ER-ratios, the degree of IBD-inflammation was differentiable beginning at 60 min after contrast application. If reproducible in men, a determination of the inflammation’s degree could finally be achieved with a non-invasive imaging modality.

 

Prostate Cancer

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  2759.     High B-Value Diffusion-Weighted MR Images of Urothelial Cancer

Mayumi Takeuchi1, Kenji Matsuzaki1, Hiromu Nishitani1

1University of Tokushima, Tokushima, Japan

We evaluated urothelial cancers by high b-value diffusion-weighted images (DWI) and corresponding isotropic ADC maps. All 45 urothelial cancers (two renal pelvic, 15 ureteral and 28 bladder cancers) showed very high intensity on DWI (ADC=1.43 +/- 0.29). The fusion images in combination of DWI and MR Urography are useful in tumor detection and in evaluation of tumor extent in the entire urinary tract. In bladder cancers DWI can provide useful information for the evaluation of depth of invasion.

                  2760.     Diffusion-Weighted Imaging for Detection and Staging of Urothelial Neoplasms

Mohit Naik1, Andew D. Hardie1, Hersh Chandarana1, Cristina H. Hajdu1, Vivian Lee1, Bachir Taouli1

1NYU Medical Center, New York, New York, USA

In this study we retrospectively evaluated the performance of DWI for detection and staging of urothelial neoplasms. All lesions were identified on high b-value DWI images and ADC of tumor was significantly lower than ADC of reference organs (urine and kidney). In addition, rADC (relative ADC=ADC tumor/ADC urine) demonstrated strong correlation with tumor stage and 100% accuracy for predicting stage III/IV tumors.

                  2761.     Comparison of Quantification Approaches in Diffusion Tensor Imaging of Prostate Cancer at 3T

Yukihisa Takayama1, Guang Jia1, Steffen Sammet1, Zarine K. Shah1, Ketul K. Shah1, Pankaj P. Dangle1, Wenle P. Wang1, Rafael E. Jimenez1, Vipul R. Patel1, Michael V. Knopp1

1The Ohio State University, Columbus, Ohio, USA

Apparent diffusion coefficient (ADC) values can be approximated by using at least two b-values but actually Diffusion-weighted images acquired with different b-values show an exponential decay, so an appropriate exponential fitting curve to calculate ADC may be more sensitive to differentiate prostate cancer. Diffusion tensor imaging has also been used as a new method to describe the diffusion in the prostate. In this study, we calculated ADC values using mono-exponential data fit and investigated if this method can help to delineate prostate cancer. DTI was also investigated if it can be additional information for prostate cancer diagnosis.

                  2762.     Diffusion-Weighted Imaging of the Prostate at 3T Using High B-Factors

Julie Absil1, Nathalie Hottat1, Thierry Metens1, Celso Matos1

1ULB - Hôpital Erasme, Brussels, Belgium

We investigated the use of DW-imaging of the prostate at 3T without endorectal coil and involving b-values superior to 1000s/mm². 31 patients with suspicious PSA-level or DRE underwent MR examinations on a 3T Philips system, using the cardiac-coil. DWI was applied with 5 b-factors : 0, 1000, 1500, 2000, 2500s/mm². ADCs were calculated with all five b-values, with b=1000 to 2500 and with b=0-1000s/mm², and results were compared to histopathology (TRUS-guided biopsies). DWI had a high sensitivity (87.5%) for the detection of suspicious lesions, but malignant and benign lesions could not be differentiated by their ADC (specificity = 53.3%).

                  2763.     Tumor Volume Measurement in Prostate Cancer Using Diffusion-Weighted Imaging: Initial Results

Yousef Mazaheri1, Amita Shukla-Dave1, Hedvig Hricak1, Samson W. Fine1, Jingbo Zhang1, Victor Reuter1, Glorai Inurrigarro1, Joanna Grater1, Kristen Laura Zakian1, Jason A. Koutcher1

1Memorial Sloan Kettering Cancer Center, New York, New York, USA

We present a method to measure prostate tumor volume using ADC maps generated from DW images.  The method uses a combined statistical ADC threshold and voxel cluster approach to measure prostate tumor volume. Our initial results suggest that tumor volumes measured on ADC maps correlate significantly with tumor volumes measured on histopathology.

                  2764.     Assessment of Prostate Cancer Aggressiveness Using Diffusion Weighted Imaging

Yousef Mazaheri1, 2, Amita Shukla-Dave1, Hedvig Hricak1, Samson W. Fine1, Jingbo Zhang1, Victor Reuter1, Gloria Inurrigarro1, Joanna Grater1, Liang Wang1, Kristen Laura Zakian1, Jason A. Koutcher1

1Memorial Sloan Kettering Cancer Center, New York, New York, USA

We present the results of a lesion-based analysis using whole-mount step-section pathology after radical prostatectomy as the standard of reference to investigate whether the apparent diffusion coefficient (ADC) values calculated from diffusion weighted images of prostate cancer lesions correlate with lesion Gleason scores.

                  2765.     Comparison of Apparent Diffusion Coefficients Derived from Histology-Defined Versus T2-W Defined
                                Regions in Prostate Cancer

 

Geoffrey S. Payne1, Sophie Riches1, Veronica Morgan1, Cyril Fisher2, Sarb Sandhu2, Nandita M. desouza1

1Royal Marsden Hospital and Institute of Cancer Research, Sutton, UK; 2Royal Marsden Hospital, London, UK

Tumours in prostate cancer may be identified directly using T2-weighted MRI, or indirectly by mapping the tumor region on a histological slice on to the T2-weighted image, using suitable warping and landmarks. This study was designed to investigate the degree of overlap and identify the consequent effect on values of tumor ADC. In 20 patients the average lesion size identified by T2w MRI was about half that identified by histology, with just under 50% overlap between them. Compared with peripheral zone, histologically-identified tumor ADC was reduced more than T2w-MRI identified tumor ADC. The mechanistic cause of this deserves further attention.

                  2766.     Spectroscopic Imaging of Prostate Cancer: A Novel Spectrum Processing Approach and Comparison
                                 with the Step-Section Histology

Jan Weis1, Håkan Ahlström1, Peter Hlavcak1, Michael Häggman1, Francsico Ortiz-Nieto1, Antonina Bergman1

1Uppsala University Hospital, Uppsala, Sweden

Verification of findings can be considered as the weakness of many MRSI studies of the prostate cancer. The majority of previous reports have used sextant biopsy. Biopsy is, however, subject to sampling errors. Only a few studies used prostatectomy step section histology as the reference. This work addresses the novel spectrum processing approach based on the combination of vendor optimized spectrum preprocessing in the scanner and user independent time-domain spectrum processing in MRUI. Our objective was quantitation of (Cho+Cr)/Cit ratio in normal and pathologic human prostate and comparison of the results with histopathology after radical prostatectomy.

                  2767.     Improved Prostate MRSI Employing a Conformal Voxel Technique

Niranjan Venugopal1, 2, Boyd McCurdy, 13, Lawrence Ryner, 12

1University of Manitoba, Winnipeg, Canada; 2National Research Council Institute for Biodiagnostics, Winnipeg, Canada; 3CancerCare Manitoba, Winnipeg, Canada

A key component in the clinical utility of prostate MRSI is the effective suppression of periprostatic lipid signal to reduce contamination artifacts. We present the first application of conformal voxel magnetic resonance spectroscopy (CV-MRS) in prostate MRSI to improve the effectiveness of outer volume lipid suppression. This method uses up to twenty Very Selective Saturation (VSS) pulses, automatically positioned in three dimensions, to “conform” the excitation voxel to the shape of the prostate, effectively nulling signal from surrounding tissue. Using this technique results in a ~75% reduction in contaminating lipid and improved quality of spectra throughout prostate.

                  2768.     Automated Prostate Cancer Detection from Magnetic Resonance Spectroscopy (MRS) Using a Hierarchical
                                Non-Linear Dimensionality Reduction Scheme

Pallavi Tiwari1, Mark Rosen2, Jeff Blume3, Jeff Weinreb, Anant Madhabushi4

1Rutgers University, New Brunswick, New Jersey, USA; 2University of Pennsylvania, Philadelphia, Pennsylvania, USA; 3Brown University, Providence, Rhode Island, USA; 4Rutgers, New Brunswick, New Jersey, USA

Automated segmentation of prostate MRS can be used to identify areas of cancer in prostate MRI/MRS at 1.5T.

                  2769.     Quantitative Analysis of Pharmacokinetic Parameters Using DCE-MRI of Prostate from Patients with
                                 Prostate Cancer Before and After Intensity-Modulated Radiotherapy

Patrik Zamecnik1, Christian Zechmann2, Frederik Lars Giesel3, Christian Thieke2, Stefan Delorme2

1German Cancer Research Center (DKFZ), Heidelberg, Germany; 2DKFZ, Heidelberg, Germany; 3DKFZ, heidelberg, Germany

The intensity-modulated radiotherapy (IMRT) is an effective option to treat prostate cancer. The aim of this work was to prove the changes of the dynamic pharmacokinetic parameters (amplitude, kep) in the prostate using DCE-MRI of patients with prostate cancer after IMRT compared to the values prior to radiotherapy in terms of definition of an effective control parameter. 24 men with histologically proved prostate cancer underwent a standardized MRI-examination before and after IMRT. In conclusion, kep showed a significant decrease after IMRT - this parameter is applicable for monitoring of  intraprostatic changes after IMRT. Amplitude showed no significant changes after IMRT.

                  2770.     A Method for Detailed Analysis of Prostate Motion Demonstrated with a Study of Bladder Filling Effect

Ben Brooks1, Steven Yang1, Gary Cowin1, Matt Meredith1, Deming Wang1

1University of Queensland, Brisbane, Australia

As part of a larger study we aim to observe prostate motion under certain conditions. In this study we trial a new registration algorithm to find the translation and rotation of the prostate under bladder filling conditions. The results are compared to Centre of Mass displacments results from litrature and our own COM results.

                  2771.     Significant Changes in Prostate Shape and Volume After Endorectal Coil Introduction, as Observed
                                 by 3T MR Imaging
 [Not Available]

Stijn Wilhelmus Heijmink1, Tom W. Scheenen1, Emile N. van Lin1, Lambertus A. Kiemeney1, Jelle O. Barentsz1

1Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands

Endorectal coil (ERC) introduction as observed by 3T MR imaging changed all prostate diameters and volume significantly. Most particularly, the mean anteroposterior diameter was reduced by approximately one-sixth of its original diameter. The mean total prostate volume was decreased by 18%. This may cause difficulties and should be considered when using ERC-based MR images for MR-CT image fusion and radiation therapy treatment planning.

                  2772.     Prediction of Extracapsular Extension of Of Prostate Cancer  with Endorectal MRI: The Effects of 
                                 Histological Tumor Size, Grade and Zonal Extent

Liang Wang1, Jingbo Zhang1, Yousef Mazaheri Tehrani1, Ishill Nicole2, Chaya Moskowitz1, Hedvig Hricak1

1Memorial Sloan-Kettering Cancer Center, New York, New York, USA; 2Memorial Sloan-Kettering Cancer Center, New York, USA

To determine whether the sensitivity of MRI in detecting extracapsular extension of prostate cancer lesions is significantly affected by any of the following histological characteristics of the lesions: greatest diameter, greatest perpendicular diameter, bi-dimensional diameter product, Gleason grade, and zonal extent.

                  2773.     Application of a “Shutter–Speed” Model to Analysis of Dynamic Contrast Enhancement in Prostate
                                Tumours

Martin Lowry1, Bashar Zelhof1, Martin D. Pickles1, Peter Gibbs1, Lindsay W. Turnbull1

1University of Hull, Hull, UK

DCE-MRI of the prostate at 3T was implemented using multiple flip angles, for T1 determination, and a rapid dynamic 3D acquisition.  Pharmacokinetic analysis using a Fast-eXchange Regime model provided improved fitting accuracy and consistently increased values of Ktrans and Ve when compared to an Fast-eXchange Limit model.  Values of tau, the mean intracellular lifetime of water, were significantly lower in tumour and BPH than in apparently normal peripheral zone.

                  2774.     Computer-Aided Diagnosis of Prostate Cancer: Clinical Utility of Integrating Model-Free and Kinetic-Based
                               Analysis of High Spatial Resolution Dynamic Contrast Enhanced 3 Tesla MRI

B. Nicolas Bloch1, Erez Eyal2, Neil M. Rofsky1, Edna Furman-Haran2, Hadassa Degani2, Elizabeth M. Genega1, William C. Dewolf1, Glenn J. Bubley1, Robert E. Lenkinski1

1Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA; 2Weizmann Institute of Science, Rehovot, Israel

The aim of this work was to assess the clinical utility of principle component analysis (PCA) to analyze DCE images of the prostate, in comparison with model-based analysis (3TP) and whole mount histopathology as the reference standard.  The temporal patterns in DCE MRI of the prostate are a linear combination of 3 orthogonal components, which were identified by PCA in 14 different patients as the three largest eigen vectors. The partition of enhancement patterns performed by PCA was similar to the partition obtained by the model based 3TP algorithm and showed a high spatial correlation with histopathology. PCA offers a computational fast, robust, model independent approach for analyzing DCE MRI and facilitates highly accurate  non-invasive prostate cancer assessment.

                  2775.     Minimizing Inflow Effect in Measured Arterial Input Function for Prostate DCE-MRI

Yuxi Pang1, Marcelino Bernardo2, 3, Baris Turkbey3, Gregory Ravizzini3, David Thomasson4, Peter Choyke3

1Philips Medical Systems, Bethesda, Maryland, USA; 2SAIC-Frederick, Frederick, Maryland, USA; 3Molecular Imaging Program, National Cancer Institute, Bethesda, Maryland, USA; 4National Institutes of Health, Clinical Center, Bethesda, Maryland, USA

Analysis of T1-wighted dynamic contrast enhanced MRI (DCE-MRI) data based on the pharmacokinetic model (Generalized Kinetic Model, GKM) could provide key diagnostic information about prostate tissue perfusion1. In order to derive meaningful pharmacokinetic parameters, it is indispensable to know an accurate arterial input function (AIF) which represents the delivery of intravascular tracer to the tissue of interests. In practice, AIF is normally taken from either right or left femoral artery areas within imaging planes. However, due to the limited scan volume coverage, none polarized blood from outside imaging volume will flow through the imaging planes resulting in apparent decreased longitudinal relaxation times T1 and thus leading to an overestimation of AIF. In this work, we propose to apply an additional RF pulse to extend the imaging volume coverage for reducing this blood inflow effect.

                  2776.     Experiences with the MRI Guided Prostate Biopy in Clinical Routine in Patients with Former Negative
                                TRUS Biopsy
 [Not Available]

Matthias Philipp Lichy1, David Schilling, Aristotelis Anastasiadis, Philipp Wagner, Arnulf Stenzl, Claus D. Claussen, Heinz-Peter Schlemmer1

1University of Tuebingen, Tuebingen, Germany

The MRI guided prostate biopsy is an invaluable add-on to the conventional TRUS biopsy, especially in cases with former negative biopsies, persisting / increasing PSA levels and suspicious MRI findings. It is a save and practical procedure, which can easily be integrated into clinical routine.

                  2777.     Clinical Evaluation of a Novel, Near-Isotropic Resolution Volume Selective 3D FSE Pulse Sequence
                                for Prostate MRI

David W. Stanley1, Manojkumar Saranathan2, Marilyn B. Wood3, James F. Glockner3, Akira Kawashima3

1GE Healthcare, Rochester, Minnesota, USA; 2Global Applied Science Laboratory, GE Healthcare, Rochester, Minnesota, USA; 3Mayo Clinic, Rochester, Minnesota, USA

Conventional multi-slice 2D Fast Spin Echo (FSE) sequences obtained in three orthogonal planes aligned to optimally visualize the prostate are used to outline the contour and zone anatomy of the prostate gland and to reveal gross tumor extension to the seminal vesicles and neurovascular bundles. Until recently, 3D FSE with high spatial resolution has been impractical due to the blurring caused by long echo-trains. In this study, we investigated a novel, volume-selective near-isotropic 3D FSE pulse sequence and its potential as an adjunct and/or replacement to conventional multiplanar 2D FSE imaging.

                  2778.     Diagnostic Accuracy of T2 Weighted MRI for Planning MRI Guided Prostate Biopsies – a Correlation with
                                Whole-Mount Sections in 70 Patients
 [Not Available]

Matthias Philipp Lichy1, Lonard Jurgschat, Joerg Hennenlotter, Ulrich Vogel, Aristotelis Anastasiadis, David Schilling, Arnulf Stenzl, Clauss D. Claussen, Heinz-Peter Schlemmer1

1University of Tuebingen, Tuebingen, Germany

T2w endoMRI can be used for planning and conduction of MRI guided prostate biopsies. Especially tumor lesions down to 0.5 cm, which are not assessable by ultrasound guided transrectal biopsy, can be assessed by this method.

                  2779.     Prostate Magnetic Resonance Imaging (MRI) at 3 Tesla: Prostate Cancer Detection and Localization
                                 in Patients with Repeat Negative Biopsies Using High Spatial Resolution Dynamic Contrast Enhanced
                                 and T2-W MRI in  Routine Clinical Practice

Boris Nicolas Bloch1, Tania Velez1, Robert E. Lenkinski1, Herbert Y. Kressel1, Martin P. Smith1, Ivan Pedrosa1, Long Ngo1, William C. Dewolf1, Elizabeth Genega1, Martin Sanda1, Neil M. Rofsky1

1Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA

The aim of the study was to  prospectively determine the value of high spatial resolution dynamic contrast enhanced (DCE-) with high spatial resolution T2 weighted (T2-W) endorectal(ER) coil magnetic resonance imaging (MRI) at 3 Tesla for detection and localization of prostate cancer in patients with repeat negative biopsies and raising prostate specific antigen (PSA) , using histopathology of the subsequent biopsy as the reference standard. This prospective study demonstrates that high spatial resolution 3 Tesla MRI improves positive prostate biopsy rates substantially by 16-48%, when compared to standard repeat biopsy. This data suggests that MRI can assist in the reduction of repeat negative biopsies in patients with raising PSA, foremost in patients with anterior (central gland) tumors, and can facilitate earlier appropriate treatment.

 

Ex Vivo MRS Studies of Tumor Metabolism

Hall D                                   Monday 14:00-16:00                                                                                                                                             

                  2800.     The Tumor Microenvironment Alters Choline Phospholipid Metabolism Detected by Comparing Cancer
                                 Cells with Tumors

Noriko Mori1, Kristine Glunde1, Tomoyo Takagi1, Zaver Bhujwalla1

1The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA

Both tumor cells in culture and solid tumor models are useful tools to study cancer biology.  Elevated phosphocholine (PC) and total choline (tCho) levels are common features in cancer cells and solid tumors.  To understand the differences in choline phospholipid metabolism between tumor cells in culture and solid tumors, we compared 1H MRS of extracts from human prostate and breast cancer cell lines grown in culture and as solid tumors.  PC/GPC ratios in highly malignant cancer cells in culture were significantly higher than in the corresponding solid tumors, indicating the importance of the tumor microenvironment in choline phospholipid metabolism.

                  2801.     Essential Role of Phospholipase A2 in Phenylbutrate-Induced Activation of Phospholipid Metabolism
 [Not Available]

Daniel-Joseph Leung1, 2, Nancy J. Beardsley1, Theresa M. Mawn1, Edward J. Delikatny1

1University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA

MR spectral changes induced by the differentiating agent phenylbutyrate (PB) in DU145 prostate adenocarcinoma cells include significant increases in mobile lipids, total choline, and glycerophosphocholine (GPC). A specific inhibitor of cytoplasmic phospholipase A2 (cPLA2) was used to determine the contribution of this critical mediator in arachidonic acid dependent cell signaling on the observed metabolic changes. AACOCF3 reversed PB-induced changes, specifically attenuating GPC formation and mobile lipid increases caused by PB. These results suggest that variations of PLA2 activity may play a role in the cellular response to differentiation therapy.

                  2802.     Quantification and Comparison of Time-Dependent Changes in Mobile Lipid Resonances with
                                Cellular Processe

Dominik Zietkowski1, Thomas Eykyn1, Nandita Desouza1, Geoffrey Payne1

1The Institute of Cancer Research, Sutton, UK

This study investigates changes in the nature and degree of saturation of mobile lipid resonances (MLRs) in relation to phases of the cell cycle and to cellular processes such as proliferation, drug-induced apoptosis (paclitaxel, etoposide), growth arrest (apicidin) and necrosis (cytochalasin B) in Hela cells. MLR changes 24h after exposure to these drugs are much more rapid than in unexposed cells. Lipid profiles of growth-arrested and apoptotic cells are almost indistinguishable. Flow cytometry data suggests that MLR changes are not cell cycle dependent as cells arrested in G1 or G2/M phases of the cell cycle display similar lipid profiles.

                  2803.     Multi-Drug Resistant Breast Cancer Cells Exhibit High Choline Kinase and Stem-Like Markers

Marie-France Penet1, Tariq Shah1, Kristine Glunde1, Noriko Mori1, Zaver M. Bhujwalla1

1Johns Hopkins University School of Medicine, Baltimore, Maryland, USA

The two main causes of treatment failure and mortality in cancer patients are multi drug resistance (MDR) and tumor metastasis.  Stem-like cancer cells are known to have increased drug resistance and contribute to tumor recurrence, but their metabolic characteristics are unexplored.  Here we have investigated breast cancer stem-like cell markers and choline metabolism in MCF-7 cells resistant to adriamycin (MCF-7/Adr) that display a MDR phenotype.  We found that MCF-7/Adr cells expressed a higher level of choline kinase with an increased phosphocholine / glycerophosphocholine ratio, and contained a higher fraction of CD44+/CD24- stem-like cells than MCF-7 wild-type cells.

                  2804.     Metabolomic Differentiation of Thyroid Malignancies with Magnetic Resonance Spectroscopy of
                                Tissue and Cytology Samples

William Faquin1, Kate W. Jordan1, Christen B. Adkins1, Leo L. Cheng1

1Massachusetts General Hospital, Boston, Massachusetts, USA

Accurate classification of thyroid malignancies is difficult due to an inability to biochemically characterize tumors. In this study HRMAS 1HMRS is used to examine paired samples of thyroid tissue and cytology from patients with papillary carcinoma, follicular adenoma, and follicular carcinoma. Metabolomic profiles generated were able to accurately identify if cancerous cells were present, and to differentiate between the three malignancies.