Traditional Posters : Other
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Elastography

 
Wednesday May 11th
Exhibition Hall  13:30 - 15:30

1474.   Interleaved Spiral Sequence for MR Elastography of the Brain  
Curtis L Johnson1, Danchin D Chen1, Armen A Gharibans1, William C Olivero2,3, Bradley P Sutton3,4, and John G Georgiadis1,3
1Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 2Department of Neurosurgery, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 3Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 4Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States

 
A spin-echo sequence with interleaved spiral readouts is implemented for Magnetic Resonance Elastography (MRE) of the brain. This novel sequence allows for high-resolution acquisitions with significantly reduced scan times in order to improve subject comfort. To our knowledge, this is the first implementation of such a sequence, and its performance is demonstrated with both phantom and in vivo brain experiments. This sequence will allow for acquisition of data sets necessary for more sophisticated MRE inversion algorithms while maintaining reasonable acquisition times.

 
1475.   Revealing the origin of attenuation in tissue: pure absorption or multiple scattering? 
Ralph Sinkus1, Sverre Holm2, Bojan Guzina3, Sven Peter Näsholm2, Philippe Garteiser1, Sabrina Doblas1, Bernard E. Van Beers1, and Valérie Vilgrain1
1Dept. of Radiology, CRB3, Hôpital Beaujon (U773), INSERM, Clichy, France, 2Dept. of Informatics, University of Oslo, Norway, 3Department of Civil Engineering, University of Minnesota, Minneapolis, United States

 
At present, the origin of the power-law behaviour of the tissues’ complex shear modulus in the frequency domain is not understood. Multiple-scattering theories do provide a physical explanation for this phenomenon but require that very-short-delay multiple reflections do occur. We demonstrate via in-vivo transient MR-Elastography for the first time that that very-short-delay multiple reflections are present in liver tissue and that they are absent in a silicon phantom. This sets the basis for further research investigating whether the predicted link between the spatial distribution of reflection coefficients and the observed dispersive behaviour of G* indeed holds.

 
1476.   MR elastography of mice in experimental autoimmune encephalitis 
Kerstin Riek1, Isabell Hamann2, Jason Millwald3, Caspar Pfueller3, Sebastian Hirsch1, Dieter Klatt3, Jürgen Braun4, Carmen Infante-Duarte3, and Ingolf Sack1
1Department of Radiology, Charité University Medicine, Berlin, Germany, 2Cecilie-Vogt-Klinik für Neurologie, Charité University Medicine, 3Charité University Medicine, 4Institute of Medical Informatics, Charité University Medicine, Berlin, Germany

 
In multiple sclerosis (MS), diffuse brain parenchymal damage exceeding focal inflammation is increasingly recognized as a major cause of clinical disability. Experimental Autoimmune Encephalitis (EAE) is an animal model of MS that enables researchers to study neuronal tissue affected by chronic inflammatory. In this study, cerebral MRE of mice is used to study the relationship between brain viscoelasticity and degree of tissue degradation during EAE. Both symptomatic and asymptomatic EAE mice presented with a significant decrease in the storage modulus with age (p<0.05). In contrast there was no correlation between examination time and complex modulus in healthy controls.

 
1477.   Prostate MRE at 3T: Trans-perineal wave propagation 
Ramin Sebastian Sahebjavaher1, Ali Baghani1, Ralph Sinkus2, and Septimiu E Salcudean1
1Electrical and Computer Engineering, University of British Columbia, Vancouver, British Columbia, Canada, 2Laboratoire Ondes et Acoustique, ESPCI, Paris, France

 
The diagnostic importance of elasticity for prostate cancer is well established; therefore, viscoelastic information acquired from in-vivo prostatic tissue using MR Elastography (MRE) is expected to provide valuable clinical information. A second harmonic MRE approach was performed on healthy subjects in supine position with the transducer applied at the perineum. Initial results show that the waves sufficiently penetrate into the prostate. Applying the mechanical excitation to the perineum is comfortable for the patients even for extended imaging examinations. The reconstructed viscoelastic values visually show a significant correspondence to the anatomy. This study shows that trans-perineal 2nd harmonic MRE is feasible.

 
1478.   Progressive Change in Biomechanical Properties of Ex vivo Prostate with Pathology Fixation as Measured by MR Elastography at 7 Tesla, and Correlation with Changes in T1, T2 and ADC 
Deirdre Maria McGrath1, Warren D Foltz1, and Kristy K Brock1,2
1Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada, 2Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada

 
Validation of medical imaging for disease detection and localization is achieved by correlation with the ‘gold-standard’ of histopathology. For accurate 3D biomechanical registration of the histopathology volume with the imaging volume, the effect of pathology fixation on biomechanical ex vivo tissue properties must be incorporated. A quasi-static MRE method at 7 tesla was applied to measure the progressive effects of formalin fixation in preclinical and clinical prostate tissue, and increases in Young’s modulus with fixation were correlated with decreases in T1, T2 and ADC. This will allow the formulation of predictive models of material property changes using standard MRI parameters.

 
1479.   Combined MRE and SPAMM tagged MRI for the analysis of large strain soft tissue mechanical properties 
Kevin Mattheus Moerman1,2, Andre M.J. Sprengers2, Ciaran Knut Simms1, Anneloes E Bohte2, Rolf M. Lamerichs3, Ralph Sinkus4, and Aart J. Nederveen2
1Trinity Centre for Bioengineering, University of Dublin, Trinity College, Dublin, Ireland, 2Radiology Department, Academic Medical Centre, Amsterdam, Netherlands, 3Philips Research, Eindhoven, Netherlands, 4Radiology Department, CRB3, Hôpital Beaujon (U773), INSERM, Clichy, France

 
The MRI based non-invasive analysis of soft tissue mechanical properties has been the focus of many fields of research. MR Elastography (MRE) allows for the estimation of shear elasticity and viscosity properties and has been shown to be beneficial in the study of liver fibrosis and breast lesions. However, this technique has mainly been limited to microscopic strain levels. Using indentation of a silicone gel soft tissue phantom the current study presents the combination of a fast SPAMM tagged MRI sequence and MRE for the analysis of the large strain mechanical behavior of soft tissue.

 
1480.   Investigation of the Anisotropic Properties of White Matter Tracts in the Human Brain using Waveguide Constrained MR Elastography 
Anthony Joseph Romano1, Michael Scheel2, Sebastian Hirsch3, Juergen Braun4, and Ingolf Sack3
1Physical Acoustics, Naval Research Laboratory, Washington, DC, United States, 2Department of Radiology, Charite Universitatsmedizin, Berlin, Germany, 3Department of Radiology, Charite-Universitatsmedizin, Berlin, Germany, 4Institute of Medical Informatics, Charite-Universitatsmedizin, Berlin, Germany

 
We apply Waveguide Constrained MR Elastography to evaluate the anisotropic properties of white matter tracts in the human brain. Diffusion Tensor Imaging is used to evaluate the pathways of the Cortico Spinal Tracts, and MR Elastography is implemented to measure the dynamic displacements within the same brain. A spatial-spectral filter is applied to the data which provides only those waves which are traveling along the white matter tracts as if they act as zero-order waveguides. A sliding window spatial Fourier transform is applied to this data to provide dispersion analysis and yield local anisotropic shear stiffness values of the tracts.

 
1481.   Magnetic Resonance Elastography of the Cerebellum 
John Zhang1, Michael Green1,2, Ralph Sinkus3, and Lynne Bilston1,4
1Neuroscience Research Australia, Randwick, NSW, Australia, 2University of NSW, Sydney, NSW, Australia, 3Centre de Recherches Biomédicales Bichat-Beaujon, INSERM U773, CRB3, Paris, France,4Prince of Wales Clinical School, University of NSW, Sydney, NSW, Australia

 
The mechanical properties of the cerebellum have never been measured previously, despite the cerebellum's importance in both neurological disease and trauma. This study presents the first measurements of cerebellum viscoelastic properties, made using MR elastography in human volunteers. The results show that the cerebellum is significantly softer than the cerebral hemispheres.

 
1482.   Wide frequency range shear modulus dispersion of soft tissue samples measured by magnetic resonance elastography 
Dieter Klatt1, Kerstin Riek2, Hassan Nuzha1, Susanne Müller3, Ingolf Sack1, and Jürgen Braun2
1Radiology, Charité - Universitätsmedizin Berlin, Berlin, Berlin, Germany, 2Medical Informatics, Charité - Universitätsmedizin Berlin, Berlin, Berlin, Germany, 3Neurology, Charité - Universitätsmedizin Berlin, Berlin, Berlin, Germany

 
Magnetic resonance elastography (MRE) reveals information about biomechanical properties related to mechanical connectivity and micromechanical order in tissue. To develop MRE towards an in vivo rheometry technique an extension of the range of mechanical excitation and a modelling of tissue properties is mandatory. Therefore wide-range modulus-dispersion MRE is introduced and applied to biological tissue samples. A powerlaw simplification was used to model the dispersion function of the complex shear modulus. In this context, brain and liver tissue show very similar viscoelastic properties, while fibrotic liver displays distinctly higher shear modulus values, similar to the anisotropic elastic constants of excised muscle.

 
1483.   Biomechanical Property Quantification of Prostate Cancer by Quasi-static MR Elastography at 7 Telsa of Radical Prostatectomy, and Correlation with Whole Mount Histology 
Deirdre Maria McGrath1, Warren D Foltz1, Navid Samavati1, Jenny Lee1, Michael A Jewett2, Theodorus H van der Kwast3, Cynthia Ménard1, and Kristy K Brock1,4
1Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada, 2Department of Surgical Oncology, Princess Margaret Hospital, Toronto, Ontario, Canada, 3Department of Pathology, University Health Network, Toronto, Ontario, Canada, 4Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada

 
Magnetic resonance elastography (MRE) holds enormous potential as a tool to guide prostate intervention for cancer, such as targeted radiation therapy, MRI-guided biopsy or high dose rate (HDR) brachytherapy. However, to assist in vivo method development quantitative data on the relative increase in biomechanical stiffness of prostate cancer above that of normal tissue is required. A high resolution quasi-static MRE method at 7 tesla has been applied to prostatectomy tissue for which the disease burden was assessed using whole-mount histology. The results revealed a high sensitivity of Young’s modulus to cancer and a strong correlation with pathology.

 
1484.   Magnetic Resonance Elastography with an air ball-vibrator 
Tomokazu NUMANO1, Yoshihiko KAWABATA2, Toshikatsu WASHIO3, Kazuyuki MIZUHARA4, Naotaka NITTA3, and Kazuhiro HOMMA3
1Radiological Science, Tokyo Metropolitan University, Arakawa, Tokyo, Japan, 2Takashima seisakusho Co.,Ltd., Hino, Tokyo, Japan, 3National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan, 4TOKYO DENKI UNIVERSITY, Tokyo, Japan

 
In this work we report on the development of a new technique for MRE vibrator based upon air ball-vibrator. It is compact vibrator that generated powerful centrifugal force vibration in the high-speed revolution of the internal-ball by compressed air. Vibration frequency and centrifugal force are freely changeable by operation of air flow volume, and replacement of internal ball. From performance test, even though the vibration frequency increase, the amount of displacement did not decrease. From agarose-gel phantom experiment, this vibrator can be used to make MR elastogram. This work shows that the use of ball-vibrator for MRE is feasible and can improve MRE image resolution by maintains adequate amount of displacement with high frequency vibrations.

 
1485.   MR elastography of liver transplant patients using parallel imaging techniques 
Dieter Klatt1, Patrick Asbach1, Carsten Kamphues2, Sebastian Hirsch1, Sebastian Papazoglou1, Jürgen Braun3, and Ingolf Sack1
1Institute of Radiology, Charite - University Medicine, Berlin, Germany, 2Dept Gen Visceral & Transplantat Surg, Charite - University Medicine, Berlin, Germany, 3Institute of Medical Informatics, Charite - University Medicine, Berlin, Germany

 
In single shot MR elastography (MRE) a short transient mechanical excitation burst is sufficient for the acquisition of an entire wave image. Single shot MRE of the liver, however, suffers from susceptibility artifacts and low SNR due to fast signal relaxation. Therefore, parallel imaging is combined with single shot MRE which improves image quality and resolution compared to previously used single-shot techniques. The new method was used to assess fibrosis in liver transplant patients. Hepatic fibrosis was diagnosed in four patients. MRE has the potential to replace biopsy for the monitoring of fibrotic changes within liver grafts.

 
1486.   Three dimensional shear wave scattering MR elastography. 
Sebastian Papazoglou1, Sebastian Hirsch1, Dieter Klatt1, Jürgen Braun2, and Ingolf Sack1
1Department of Radiology, Charité University Medicine, Berlin, Berlin, Germany, 2Institute of Medical Informatics, Charité University Medicine, Berlin, Berlin, Germany

 
In magnetic resonance elastography shear elasticity of soft tissues is traditionally determined on basis of measured displacement wave data. Especially in strongly heterogeneous tissues such as the brain, standard inversion techniques may miss diagnostically valuable structural information. In contrast to the displacement field, the information content of intensity is related to characteristic length scales of shear wave scattering. In this study we demonstrate that 3D shear wave scattering MRE based on the distribution of shear wave intensity in gel phantoms is capable of revealing structural information even when wave inversion suggests similar elastic properties.

 
1487.   Validation of Fast Dynamic SPAMM Tagged MRI Based Measurement of Non-linear 3D Soft Tissue Deformation 
Kevin Mattheus Moerman1,2, Andre M.J. Sprengers2, Ciaran Knut Simms1, Rolf M Lamerichs3, Jaap Stoker2, and Aart J. Nederveen2
1Trinity Centre for Bioengineering, University of Dublin, Trinity College, Dublin, Ireland, 2Radiology Department, Academic Medical Centre, Amsterdam, Netherlands, 3Philips Research, Eindhoven, Netherlands

 
Current SPAMM methods typically construct data from many repeated motion cycles. However discomfort and health issues may preclude a large number of repetitions. The current study presents the validation of a novel fast SPAMM sequence for the measurement of dynamic 3D soft tissue deformation following just 3 repeated motion cycles. The techniques were validated using marker tracking in a silicone gel phantom and demonstrated a mean displacement difference of 0.07mm (standard deviation 0.6mm). Since only 3 motion cycles are required the presented methods are the fastest currently available for the dynamic measurement of non-linear 3D soft tissue deformation.

 
1488.   Cross-Platform Comparison of Brain MRE 
Matthew C Murphy1, Kevin J Glaser1, Bradley D Bolster, Jr.2, Daniel V Litwiller3, Scott A Kruse1, and Richard L Ehman1
1Department of Radiology, Mayo Clinic, Rochester, MN, United States, 2MR R&D Collaborations, Siemens Healthcare, Rochester, MN, United States, 3Global Applied Science Laboratory, GE Healthcare, Rochester, MN, United States

 
MRE is a phase-contrast MRI technique for noninvasively measuring tissue stiffness. MRE of the brain is currently under investigation for its potential to aid in the diagnosis of brain diseases. A robust brain MRE exam should be reproducible even when performed on different MR platforms. The purpose of this work was to assess the reproducibility of MRE of the brain on two platforms manufactured by GE and Siemens. The results indicate that the two platforms yield significantly correlated stiffness measurements, and that the mean measurements on each platform do not differ from each other.

Traditional Posters : Other
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Non-Proton MRI

 
Thursday May 12th
Exhibition Hall  13:30 - 15:30

1489.   In Vivo Sodium Imaging of Kidney Using 3D Ultrshort Echo Time Sequence 
Raffi Kalayciyan1, Friedrich Wetterling1, Sabine Neudecker2, and Lothar R. Schad1
1Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany, 2Medical Research Center, Heidelberg University, Mannheim, Germany

 
Tissue sodium concentration (TSC) serving as a biomarker for tissue viability and integrity has been investigated using the 3D-Ultrashort Echo Time (3D-UTE) to explore the corticomedullary sodium concentration gradient in the rat kidney. For the first time, 3D-UTE allowed TE as short as 60µs to record 23Na MR images of rat’s kidneys. Hence, the low SNR in sodium renal MRI has been improved over currently used 3D-GRE imaging technique by factor 3 for in vivo 23Na MRI which will enable the measurement of TSC as a marker for tissue viability and tissue integrity changes after kidney transplant.

 
1490.   High resolution in-vivo measurement of sodium T1 of human knee cartilage 
Rebecca Emily Feldman1, Robb Stobbe1, Ander Watts1, and Christian Beaulieu1
1Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada

 
Sodium MRI is a promising diagnostic technique for assessing cartilage health in vivo. The measurement of the sodium T1 for tissues in the knee is important for the development of optimized pulse sequences. Literature provides in vitro T1 values for sodium in human and bovine cartilage, but no in-vivo values. We have measured sodium T1 for cartilage, blood, and synovial fluid in-vivo at 4.7 T for five healthy subjects. We then use the differences in those T1 values to obtain a high-resolution inversion-recovery fluid-suppressed image of human knee cartilage.

 
1491.   Chemical Shift Sodium Imaging of the Rat Brain during TmDOTP5- Infusion 
Patrick Michael Heiler1, Saema Ansar2, Saskia Grudzenski2, Friedrich Wetterling1, Simon Konstandin1, Stephen Meairs2, Marc Fatar2, and Lothar Rudi Schad1
1Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany, 2Experimental Neurology, Heidelberg University, Mannheim, Germany

 
The paramagnetic lanthanide chemical shift agent TmDOTP5- is used in chemical shift imaging experiments and the technique is applied to an animal model of stroke model. It could be shown that TmDOTP5- induces a large hyperfine shift crossing neither the cell membrane nor the blood brain barrier. In ischemia, induced by occlusion of the MCA, TmDOTP5- shifts parts of the total sodium signal which indicates a disruption of the blood brain barrier.

 
1492.   Intracellular Volume Fraction Measurements using Single Quantum Sodium MRI. 
Lazar Fleysher1, Donatello Arienzo1,2, Niels Oesingmann3, and Matilde Inglese1,4
1Radiology, NYU School of Medicine, New York, New York, United States, 2Biobehavioral SCI, UCLA, United States, 3Siemens Medical Solutions USA, Malvern, PA, United States, 4Neurology, NYU School of Medicine, New York, New York, United States

 
In this work we present a method based on sodium MRI which is capable of assessing intracellular sodium volume fraction (ISVF) in-vivo. We find that ISVFGM=81±5 % and ISVFWM = 91±2% which is in a good agreement with previous invasive studies.

 
1493.   A comparison of imaging sequences for sodium MR imaging on a 9.4T whole body machine 
Sandro Romanzetti1, Christian Carlo Mirkes1, Daniel Fiege1, A. A. Celik1, Jörg Felder1, and N. J. Shah1,2
1Institute of Neuroscience and Medicine, Research Centre Juelich, 52425 Juelich, NRW, Germany, 2Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, 52074 Aachen, Germany

 
Sodium imaging at ultrahigh fields encounters signal-to-noise ratio (SNR) limitations which pose new challenges. Six sequences have been implemented on a 9.4T whole-body scanner and phantom images have been acquired. Individual strengths and weaknesses in SNR, PSF and T2* weighting can be observed. Spiral sequences seem to match the requirements for fast sodium imaging at ultrahigh fields best.

 
1494.   Clinically-Constrained Resolution-Optimized flexTPI Acquisition Parameters for the Tissue Sodium Concentration Bioscale 
Ian C Atkinson1, AIming Lu1, and Keith R Thulborn1
1Center for Magnetic Resonance Research, University of Illinois at Chicago, Chicago, IL, United States

 
Rapid transverse relaxation during signal acquisition results in T2-blurring of 23-sodium MR images. Resolution optimized acquisition parameters for quantitative 23-sodium MR imaging of the human brain are determined and demonstrated at 9.4T and 3.0T

 
1495.   High-Resolution Sodium Imaging of the Human Brain at 4T 
Daniel Pascal Fiege1, Christian Carlo Mirkes1, Ana-Maria Oros-Peusquens1, Sandro Romanzetti1, and N. Jon Shah1,2
1Institute of Neuroscience and Medicine, Forschungszentrum Jülich, Jülich, NRW, Germany, 2Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, NRW, Germany

 
Sodium MR images are usually low in resolution due to an inherently low signal-to-noise ratio. We have optimised a Cartesian gradient echo sequence for a nominal 2mm isotropic resolution. Images of a male volunteer acquired in 16 sessions were co-registered and averaged. The resulting sodium images show detailed anatomy and excellent correspondence to proton anatomical reference images.

 
1496.   Total sodium brain concentrations in compartments of patient with Multiple Sclerosis. A preliminary in vivo 23Na MRI study 
Wafaa Zaaraoui1, Simon Konstandin2, Armin M Nagel3, Tobias Wichmann4, Dominik Berthel4, Sylviane Confort-Gouny1, Patrick J. Cozzone1, Bertrand Audoin1,5, Jean Pelletier1,5, Lothar R. Schad2, and Jean-Philippe Ranjeva1
1CRMBM UMR CNRS 6612, Marseille, France, Metropolitan, 2Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany, 3Department of Medical Physics in Radiology, Heidelberg, Germany, 4Rapid Biomedical GmbH, Rimpar, Germany, 5Pôle de Neurosciences Cliniques, Service de Neurologie, Hôpital de La Timone, Marseille, France, Metropolitan

 
This study aims to compare total sodium signals (tNa) from the various brain compartments (whitte matter (WM) and grey matter (GM)) obtained in healthy controls with those in the normal appearing WM, GM and WM lesions of a patient suffering from multiple sclerosis (MS). Explorations were performed on a 3T Verio Siemens system with a 8-element 23Na receive coil using a 3D density adapted radial projection pulse sequence (TE=550µs). Elevated tNa signals were evidenced in all brain compartments of the patient. This preliminary study suggests that 23Na MRI is a promising marker of diffuse pathophysiological occurring in MS.

 
1497.   Simultaneous single-quantum and triple-quantum filtered sodium images at 4T in vivo 
Daniel Pascal Fiege1, Sandro Romanzetti1, and N. Jon Shah1,2
1Institute of Neuroscience and Medicine, Forschungszentrum Jülich, Jülich, NRW, Germany, 2Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany

 
Triple-quantum filtered sodium imaging suffers from a low signal-to-noise ratio. A sequence to simultaneously acquire tissue sodium concentration weighted images with the triple-quantum filtered images has been developed. The triple-quantum filtered images remain unchanged and additional images are acquired without an extension of the measurement time. In vivo experiments show good results.

 
1498.   In vivo quantification of Tissue Sodium Concentration in the human brain by means of a centric SPRITE sequence at 4T 
Sandro Romanzetti1, and N. J. Shah1,2
1Institute of Neuroscience and Medicine, Research Centre Juelich, Juelich, Germany, 2Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, 52074 Aachen, Germany

 
Centric SPRITE sequences can acquire images at ultrashort echo times and are not greatly affected by T2* effects. This is a fundamental feature for the quantification of tissue sodium concentration (TSC) in the brain. Furthermore, the insensitivity to B0 inhomogeneities and chemical shift artefacts of this sequences reduce corrections to just an acquisition of a single RF excitation map. In this study, a TSC map of the brain of a healthy human brain was obtained for the first time by using this sequence. Application to pathologies where local changes of sodium distribution are indicative of disease status are foreseen.

 
1499.   Intracellular Lithium by 7Li MRS: Effect of Total Li Concentration in Brain 
Richard A Komoroski1, Diana M Lindquist2, and John M Pearce1
1Center for Imaging Research, University of Cincinnati, Cincinnati, OH, United States, 2Imaging Research Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States

 
Intracellular lithium in brain in vivo can be estimated from the biexponential T2 behavior of the localized 7Li MRS signal. We report biexponential 7Li T2 relaxation studies in rat brain at 7 T with isotopically enriched 7LiCl to determine the compartmental distribution of Li as a function of brain Li concentration and to assess reproducibility and performance of a simple linear approximation to estimate intracellular Li from monoexponential T2 decay.

 
1500.   Measurement of CMRO2 changes by somatosensory stimulation in rat using oxygen-17 at 16.4 T 
Hannes Michel Wiesner1, Rolf Pohmann1, David Zsolt Balla1, Wei Chen2, Kâmil Ugurbil2, and Kamil Uludag3
1High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany, 2Radiology, Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, United States, 3MBIC, Department of Cognitive Neuroscience, Maastricht University, Maastricht, Netherlands

 
Cerebral metabolic rate of oxygen (CMRO2) is a key indicator of brain function. We measured oxygen consumption non-invasively by imaging mitochondrial turn-over rate into H217O using inhalations of enriched 17O2 gas combined with 1H-BOLD methods in the same animal and session. We present estimated CMRO2 changes in the rat somatosensory cortex, which are based on chemical shift imaging (CSI) acquisitions colocalized with 1H-BOLD fMRI acquired at a field strength of 16.4 T. The dependence of Capital Greek DeltaCMRO2 and BOLD-signal on the baseline physiology and stimulation parameters are discussed.

 
1501.   Simultaneous 23Na/1H Imaging with Dual Excitation and Double Tuned Birdcage Coil 
Christian Stehning1, Jochen Keupp1, and Jürgen Rahmer1
1Philips Research Laboratories, Hamburg, Germany

 
A simultaneous 1H/23Na MR imaging sequence with dual RF excitation and sampling is presented. Sodium and proton images are acquired simultaneously using a dual tuned coil, which eliminates the need for an additonal 1H scan and eliminates the risk of misregistration.

 
1502.   Application of Compressed Sensing to 19F turbo spin echo chemical shift imaging 
Thomas Christian Basse-Luesebrink1,2, Johannes Beck1, Thomas Kampf1, Andre Fischer1,3, Gesa Weise2, Guido Stoll2, and Peter Michael Jakob1,3
1Experimental Physics 5, University of Wuerzburg, Wuerzburg, Bavaria, Germany, 2Neurology, University of Wuerzburg, Wuerzburg, Bavaria, Germany, 3Magnetic Resonance Bavaria, Wuerzburg, Bavaria, Germany

 
The application of compressed sensing (CS) to 19F steady-state free precession chemical shift imaging (ssfp-CSI) was recently introduced for fast acquisition of spatially resolved spectral 19F data. Turbo spin echo-based CSI (TSE-CSI) was previously used to allow an accelerated acquisition of multiple 19F markers. The current work focuses on combining CS with TSE-CSI to (A) increasingly accelerate the acquisition process; (B) take advantage of the long T2 relaxation times of certain perfluorocarbon (PFC) 19F markers; and (C) retain the ability of CSI to distinguish between different 19F markers.

Traditional Posters : Other
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Hyperpolarized C13

 
Monday May 9th
Exhibition Hall  14:00 - 16:00

1503.   Comparison of Models for Analysis of Flux Through Lactate Dehydrogenase in Glioblastoma Cells Using Hyperpolarized [1-13C]Pyruvate 
Crystal Harrison1, Ralph J. DeBerardinis2,3, Chendong Yang2, Ashish K. Jindal1, A. Dean Sherry1,4, and Craig R. Malloy1,5
1Advanced Imaging Research Center, UT Southwestern, Dallas, TX, United States, 2Pediatrics, UT Southwestern, Dallas, TX, United States, 3McDermott Center for Human Growth and Development, UT Southwestern, Dallas, TX, United States, 4Chemistry, UT Dallas, Richardson, TX, United States, 5Veterans Affairs, North Texas Health Care System, Dallas, TX, United States

 
Combining data collected by hyperpolarization (HP) and mass spectrometry (MS) in identical model systems allows greater insight into the metabolic exchange of pyruvate and lactate through lactate dehydrogenase (LDH). Glioblastoma cells were investigated with these two techniques following addition of [1-13C]pyruvate or [3-13C]pyruvate. Various first-order models were investigated utilizing the pyruvate C2 and lactate C1 HP signals acquired with selective excitations and the intracellular and extracellular lactate labeling provided by MS. A three-pool bidirectional model is an accurate description of pyruvate metabolism in these cells; however the initial flux through LDH can be measured accurately regardless of the model chosen.

 
1504.   In situ polarization measurement of hyperpolarized solutions prior to in vivo 9.4T MR experiments 
Tian Cheng1, Mor Mishkovsky1,2, and Arnaud Comment1,2
1Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, 2Department of Radiology, Université de Lausanne, Lausanne, Switzerland

 
In vivo hyperpolarized MR via dissolution DNP necessitates the transfer of the hyperpolarized solutions from the DNP polarizer to the imager prior to in vivo measurements. This process leads to unavoidable losses in polarization which are difficult to evaluate once the solution is infused into the animal. We propose a method to measure the polarization of the hyperpolarized solutions inside the imager bore at the time of the infusion. This in situ calibration allows to decouple potential problems linked to the hyperpolarization and transfer processes from in vivo acquisition issues and can lead to accurate analyses of in vivo SNR.

 
1505.   Hyperpolarized [1-13C]-Lactate as a Tool for the In Vivo Investigation of Cardiac Metabolism 
Dirk Mayer1,2, Yi-Fen Yen3, Ralph Hurd3, Sonal Josan1,2, Jae Mo Park2, Adolf Pfefferbaum1,4, and Daniel Spielman2
1Neuroscience Program, SRI International, Menlo Park, CA, United States, 2Radiology, Stanford University, Stanford, CA, United States, 3GE Healthcare, 4Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, United States

 
The feasibility of both polarizing [1-13C]-lactate and detecting its metabolic conversion in vivo has previously been demonstrated. As lactate serves as an important energy source for the heart, hyperpolarized lactate could potentially be used as an alternative to pyruvate for probing heart metabolism. The aim of this work was to apply hyperpolarized [1-13C]-lactate to the measurement of cardiac metabolism and compare it to [1-13C]-pyruvate as a substrate. The presented data demonstrate that bicarbonate as a secondary product of hyperpolarized [1-13C]-lactate can be detected in the heart.

 
1506.   Design and Performance of a Multi-Sample Dissolution Dynamic Nuclear Polarization Setup 
Michael Batel1, Marcin Krajewski2, Kilian Weiss2, Oliver With1, Alexander Däpp1, Andreas Hunkeler1, Martin Gimersky3, Matthias Ernst1, and Sebastian Kozerke2
1Laboratory of Physical Chemistry, ETH Zürich, Zürich, Switzerland, 2Institute for Biomedical Engineering, University and ETH Zürich, Zürich, Switzerland, 3Laboratory for Electromagnetic Fields and Microwave Electronics, ETH Zürich, Zürich, Switzerland

 
A multi-sample dissolution DNP system compatible with commercial wide-bore magnets is presented. The system is designed to accommodate up to six samples on a revolver-style sample changer permitting exchange at liquid Helium temperatures. The system includes EPR and NMR capabilities for monitoring purposes. 13-C DNP enhancements for pyruvic acid with the trityl radical OX63 are reported. In the solid-state 21% polarization is reached and in the dissolved liquid-state the enhancement factor measured is more than 12000 at 7 T.

 
1507.   Multi-band Frequency Encoding Method for Metabolic Imaging with Hyperpolarized [1-13C]Pyruvate 
Cornelius von Morze1, Galen Reed1, Peter J Shin1, Peder E Larson1, Robert Bok1, Simon Hu1, and Daniel B Vigneron1
1Department of Radiology and Biomedical Imaging, UCSF, San Francisco, CA, United States

 
We describe a new method for metabolic imaging of multiple hyperpolarized 13C compounds based on frequency encoding of a single echo. This approach capitalizes on the large chemical shifts between 13C resonances to achieve comparable or faster speeds than previous fast MRSI approaches, while avoiding complex acquisition and reconstruction methods. The method was tested in application to metabolic imaging studies of [1-13C]pyruvate and its metabolic products lactate and alanine in preclinical normal and transgenic murine models of prostate cancer. Elevated lactate signals were observed in the prostatic regions of the tumor mice corresponding to regions of T2-weighted signal changes.

 
1508.   The Spin-Lattice Relaxation of Hyperpolarized 89Y Complexes 
Ashish K Jindal1, Lloyd Lumata1, Yixun Xing2, Matthew E Merritt1, Piyu Zhao2, Craig R Malloy1, A Dean Sherry1,2, and Zoltan Kovacs1
1Advanced Imaging, UT Southwestern Medical Center, Dallas, Texas, United States, 2Department of Chemistry, University of Texas at Dallas, Richardson, Texas, United States

 
The extremely long T1 (up to 10 minutes) and T 2 (up to 15 seconds) of 89Y, coupled with 100% natural abundance, ½ spin, and narrow linewidth, make it an attractive nucleus for hyperpolarized in vivo imaging. Here we present accurate T1 measurements of hyperpolarized 89Y – DTPA, DOTA, EDTA, and deuterated EDTA complexes. Results suggest that substitution of low-gamma nuclei on the ligand backbone as opposed to that of the solvent most effectively increase the 89Y T1. These results are encouraging for in vivo applications as the presence of bound water may not dramatically affect the T1.

 
1509.   Novel contrast mechanism via ParaHydrogen SElf Rfocussing 
Jan Falk Dechent1,2, Lisandro Buljubasich2, Laura Maria Scheiber1, Hans Wolfgang Spiess2, and Kerstin Münnemann2
1Section of Medical Physics, Johannes Gutenberg University Medical Center, Mainz, Germany, 2Max Planck Institute for Polymer Research, Mainz, Germany

 
A major challenge in molecular imaging is the detection of tiny amounts of interesting molecules. Hyperpolarization can overcome the problem of low sensitivity in Nuclear Magnetic Resonance (NMR) or Magnetic Resonance Imaging (MRI). For the most widely used nucleus 1H, however, this strategy is limited due to the high number of background protons inside the body. By using the antiphase character of Parahydrogen Induced Polarization we developed a novel 1H NMR contrast. It allows for the selective detection of a small number of hyperpolarized protons with antiphase NMR/MRI signal in the presence of a large number of thermally polarized protons.

 
1510.   The Effect of Hyperpolarized [1-13C]Pyruvate Concentration on Metabolism in the Perfused Heart 
Daniel Ball1, Marie Schroeder1, George Radda1, Kieran Clarke1, and Damian Tyler1
1Department of Physiology, Anatomy and Genetics, Oxford University, Oxford, Oxfordshire, United Kingdom

 
Hyperpolarized 13C-pyruvate is widely used in assessing cardiac metabolism in the perfused rat heart. Typically large concentrations are infused (~2mM) when compared to physiological levels (~60µM). This is done to achieve sufficient signal-to-noise in the acquired spectra. Given that pyruvate is used as a real-time measure of enzymatic flux, it is important to understand the effect of high pyruvate concentrations on the kinetics observed. The aim of this study was to assess varying concentrations of pyruvate to determine when enzyme kinetics become unrepresentative of the physiological state and to find a suitable compromise between high signal and accurate metabolic assessment.

 
1511.   In Vivo Measurement of Normal Rat Intracellular Pyruvate and Lactate Levels after Injection of Hyperpolarized [1-13C]Alanine 
Simon Hu1, Hikari Yoshihara1, Robert Bok1, Peder E Larson1, John Kurhanewicz1, and Daniel B Vigneron1
1Dept. of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, CA, United States

 
The most commonly used in vivo agent in hyperpolarized 13C metabolic imaging thus far has been [1-13C]pyruvate. In preclinical studies, not only is its uptake detected but also its intracellular enzymatic conversion to metabolic products including [1-13C]lactate. However, the ratio of 13C-lactate/13C-pyruvate measured in this data does not accurately reflect cellular values since much of the [1-13C]pyruvate is extracellular depending on timing, vascular properties and extracellular space and monocarboxylate transporter activity. In order to measure the relative levels of intracellular pyruvate and lactate, in this project we hyperpolarized [1-13C]alanine and monitored the in vivo conversion to [1-13C]pyruvate and [1-13C]lactate.

 
1512.   Effect of Lanthanide Ions on Dynamic Nuclear Polarization Enhancement and Liquid State T1 Relaxation 
Jeremy Gordon1, Ian Rowland1,2, Eric Peterson3, and Sean Fain1,2
1Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, 2Department of Radiology, University of Wisconsin-Madison, Madison, WI, United States,3Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States

 
Gadolinium has been previously reported to increase the solid-state polarization of 1-13C pyruvate. However, gadolinium is a potent relaxation agent in the liquid state, decreasing the time available for imaging experiments for polarized nuclei. This work studies the effects of doping pyruvate solutions with lanthanides on the solid-state polarization, buildup time, and liquid-state T1. Holmium, another paramagnetic lanthanide, was found to increase the solid-state polarization at low (0.5mM) concentrations with favorable relaxation properties in the liquid state.

 
1513.   Probing the relaxation mechanism that interferes with polarization measurement using the C2 doublet of 1,2-[13C]2-pyruvate 
Justin Yat Cheong Lau1,2, Albert P Chen3, Jianfeng Zhu4, Gang Wu4, and Charles H Cunningham1,2
1Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada, 2Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada, 3GE Healthcare, Toronto, Ontario, Canada, 4Department of Chemistry, Queen's University, Kingston, Ontario, Canada

 
A current challenge with tracking C1 polarization by selective small tip angle excitation of C2 in 1,2-[13C]2-pyruvate is the observed evolution of the C2 doublet beyond AB asymmetry. We hypothesize that cross coupling between the dipolar field and chemical shift anisotropy (CSA) may, at least in part, be responsible for this behaviour. This study shows that solution pH has an effect on the relaxation mechanism that currently interferes with polarization measurement using C2 asymmetry of 1,2-[13C]2-pyruvate, suggesting that the C2 CSA of the protonated form may be less effective at coupling with the dipolar field.

 
1514.   The Influence of Bovine Serum Albumin on the T1 Relaxation of [1-13C]Pyruvate – A Study at Low Fields 
Benjamin M. Pullinger1, Stephen J. Kadlecek1, Nicholas N. Kuzma1, and Rahim R. Rizi1
1Radiology, University of Pennsylvania, Philadelphia, PA, United States

 
The effects of bovine serum albumin (BSA) on the T1 relaxation of DNP-hyperpolarized [1-13C]Pyruvate are studied as a function of magnetic field at varying concentrations of BSA and the DNP radical OX063 trityl. At low fields of 27.0 and 15.8 gauss the carbon-13 relaxation times are shortened by factors of 3 and 4 after addition of only 3% BSA. Our data suggests that caution should be taken in transporting hyperpolarized [1-13C]Pyruvate in the presence of albumin.

 
1515.   Optimisation of Murine Cardiac Hyperpolarized Magnetic Resonance Spectroscopy Using Dynamic Nuclear Polarization 
Michael Samuel Dodd1, Beat Schuler1, Vicky Ball1, Daniel Ball1, George K Radda1, Houman Ashrafian2, Hugh Watkins2, Kieran Clarke1, and Damian J Tyler1
1Physiology, Anatomy and Genetics, Oxford University, Oxford, United Kingdom, 2Cardiovascular Medicine, Oxford University, Oxford, United Kingdom

 
Alterations in cardiac metabolism underlie many diseases of the heart. The advent of cardiac hyperpolarized magnetic resonance spectroscopy, via dynamic nuclear polarization, has enabled a greater understanding of the in vivo metabolic changes seen as a consequence of heart disease. This study demonstrates for the first time a slice selective approach to investigate the in vivometabolism of [1-13C]pyruvate in the murine heart. There is a significant 64% reduction in PDH flux in the fasted murine heart, similar to previous findings in the rat. This work validates the method for detecting changes in transgenic murine models of cardiovascular disease.

 
1516.   Hepatic Hyperpolarized 13C Pyruvate Studies: Origin of Additional in vivo Pyruvate Resonances 
Eric T Peterson1, Jeremy W Gordon2, Sean B Fain2, and Ian J Rowland2
1Biomedical Engineering, University of Wisconsin - Madison, Madison, WI, United States, 2Medical Physics, University of Wisconsin - Madison, Madison, WI, United States

 
Hepatic metabolism studies using hyperpolarized 13C pyruvate often yield additional resonances associated with pyruvate and pyruvate hydrate. To investigate the origin of these additional resonances, we have used spectrally sensitive imaging and intravenous gadolinium-based contrast agent. Spectral information strongly suggested that the additional resonances derive from the vena cava. This is attributed to bulk magnetic susceptibility effects due to alignment parallel with B0. Intravenous contrast diminished the additional high field but not the low field resonances, supporting the conclusion that the additional peaks arise predominantly from an intravascular compartment.

 
1517.   Retaining Polarization by exploiting reduced T1 relaxation of hyperpolarized spins at low field in solution 
Mark Van Criekinge1, Kayvan R. Keshari2, Daniel Vigneron2, and John Kurhanewicz2
1UCSF, San Francisco, CA, United States, 2UCSF

 
An important consideration for performing hyperpolarized (HP) 13C-MR studies is matching the T1 relaxation time of the HP 13C-labeled probe with the time scale of the metabolic process being investigated. By evolving the hyperpolarized spins in low field (<0.1T), a dramatic increase in [1-13C]pyruvate relaxation rate was indirectly observed as a 50% increase in residual polarization. For in vivo studies, it is possible that hyperpolarized spins could be allowed to evolve inside of animals at low field, in the fringe field of the magnet, and subsequently transport them into the magnet at a later time to observe slower enzyme kinetics.

 
1518.   Determination of Optimal Model Sampling Parameters for Hyperpolarized Contrast Agents 
Eric T Peterson1, Matthew R Smith2, Joseph J Grudzinski2, Jeremy W Gordon2, and Sean B Fain1,2
1Biomedical Engineering, University of Wisconsin - Madison, Madison, WI, United States, 2Medical Physics, University of Wisconsin - Madison, Madison, WI, United States

 
Hyperpolarized carbon metabolic imaging and spectroscopy have been shown to non-invasively probe in vivo metabolic and transport parameters. This work presents a method which can be used to determine the optimal sampling times and flip angles for any symbolically represented parametric model, or any model where the Fisher Information Matrix may be calculated, in order to maximize the parametric SNR of the acquisition. This allows a substantial increase in the parametric SNR for any imaging or spectroscopy sequence.

 
1519.   Generation of hyperpolarised materials for magnetic resonance using high-field cryogenics 
David G Gadian1, Kuldeep S Panesar2, Angel J Perez Linde3, Waldemar Senczenko3, Anthony J Horsewill2, Walter Kockenberger3, and John R Owers-Bradley2
1Imaging & Biophysics Unit, UCL Institute of Child Health, London, United Kingdom, 2School of Physics & Astronomy, University of Nottingham, Nottingham, United Kingdom, 3Sir Peter Mansfield MR Centre, School of Physics & Astronomy, University of Nottingham, Nottingham, United Kingdom

 
There is increasing interest in the development of techniques for hyperpolarising nuclei, with a wide range of potential applications, both in vivo and in vitro. Here, we show that high-field cryogenics (ie the so-called brute-force approach), when applied in conjunction with relaxation switches and low-field thermal mixing, can be used to generate large increases in nuclear polarisation on a realistic timescale. Among the technical advantages of this approach, the polarisation process does not involve any resonance phenomena or radiofrequency irradiation. In addition, the process is completely broadband; thus a wide range of nuclear species could be polarised simultaneously.

 
1520.   Surface coils for cardiac imaging using Hyperpolarized 13C at 3 T 
William Dominguez-Viqueira1, Angus Z Lau1,2, Albert P Chen3, and Charles H Cunningham1,2
1Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada, 2Medical Biophysics, University of Toronto, Toronto, Ontario, Canada, 3GE Healthcare, Toronto, Ontario, Canada

 
Hyperpolarized-13C substrates has become a promising tool to study real-time cardiac-metabolism in-vivo. For such fast imaging it is important to optimize the RF-coils to obtain the best signal-to-noise ratio possible. A single-channel transmit/receive surface-coil for hyperpolarized-13C was characterized with benchtop and in-vivo measurements. SNR of up to 40 units was measure in-vivo, and further improvement throughout the volume of interest can be achieved by using the dual-channel surface-coil simulated in this work. This will allow imaging of the different metabolite signals even in the posterior regions of the myocardium, which is not possible at this moment with the single-channel surface-coil.

 
1521.   First step to 19F Hyperpolarization of Biocompatible Substrates Generated via Parahydrogen-Transfer 
Ute Bommerich1, Thomas Trantzschel2, Joachim Bargon3, Gerd Buntkowsky4, and Johannes Bernarding2
1SLNIB, Leibniz Institute for Neurobiology, Magdeburg, Germany, 2IBMI, University of Magdeburg, Magdeburg, Germany, 3Institute of Physical Chemistry, University of Bonn, Bonn, 4Eduard-Zintl-Institute for Inorganic and Physical Chemistry, Technical University Darmstadt

 
The generation of hyperpolarized substrates for sensitivity enhancement in MRI and MRS investigations is an emerging field. Hyperpolarization methods lead to a strong signal enhancement enabling the detection of even low concentrated substrates. As 19F nuclei do not appear in soft tissue, hyperpolarized 19F reporter molecules can provide optimal contrast for MR examinations. PHIP (ParaHydrogen Induced Polarization) is successfully applied for sensitivity enhancement but so far only a few substances are proven to exhibit 19F hyperpolarization. In this contribution we present spectra of hyperpolarized 19F nuclei detected from the first hydrogenation step to a biocompatible substrate.

 
1522.   Advanced Parallel Imaging Techniques for Metabolic Imaging with Hyperpolarised 13C 
Rolf F Schulte1, Jonathan I Sperl1, Axel Haase2, Marco Irkens3, Michael Manglberger3, Eliane Weidl4, Guido Kudielka1, Markus Schwaiger4, and Florian Wiesinger1
1GE Global Research, Munich, Germany, 2IMETUM, Technische Universitaet Muenchen, Munich, Germany, 3Rapid Biomedical, Würzburg, Germany, 4Department for Nuclear Medicine, Technische Universitaet Muenchen, Munich, Germany

 
Metabolic imaging of hyperpolarised [1-3C]pyruvate and its downstream metabolites requires efficient encoding methods. Parallel imaging is widely applied to 1H MRI, but not yet to hyperpolarised MRI. In this work, IDEAL spiral CSI was combined with parallel imaging and advanced reconstruction methods. CG SENSE and SPIRiT were compared to gridding reconstruction and regular SENSE unfolding. Results in kidney show high quality dynamic data with improved SNR for SPIRiT and CG SENSE.

Traditional Posters : Other
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Perfusion & Permeability Methodology

 
Tuesday May 10th
Exhibition Hall  13:30 - 15:30

1523.   Classification of two-site exchange models for DCE-MRI 
Steven Sourbron1, and David L Buckley1
1Division of Medical Physics, University of Leeds, Leeds, United Kingdom

 
The Tofts models have long been regarded as a standard approach to tracer-kinetic analysis of DCE-MRI, but recent technological advances have improved DCE-MRI data quality to a point where more complex models are required. Several alternatives have been proposed, but analytical solutions are either not available or too complex to offer much physical insight. Here, a generalisation is proposed which offers a transparent way of representing the architecture of existing alternatives, and constructing approximations with any desired accuracy. In addition, it allows modelling of more realistic tissues intermediate between the ideals of a compartment or a plug-flow model.

 
1524.   Effect of T1 and flip angle errors on hepatic arterial fraction calculation 
Daniel Wilson1
1Medical Physics, Leeds Teaching Hospitals, Leeds, West Yorkshire, United Kingdom

 
Hepatic arterial fraction is often measured from dynamic contrast enhanced MRI data collected using a 3D spoiled gradient echo sequence. Errors in hepatic arterial fraction measurements as a consequence of flip angle and pre contrast T1 measurement errors are minimized if higher flip angles are used. The small errors found suggest that if a flip angle of 30° is prescribed then it is possible to use an assumed T1 rather than measure it.

 
1525.   Quantification of blood-brain barrier permeability in the mouse brain in vivo: a longitudinal study 
Jieun Kim1, Nancy Berman2, and Phil Lee1
1Hoglund Brain Imaging Center, University of Kansas Medical Center, Kansas City, KS, United States, 2Department of Anatomy & Cell Biology, University of Kansas Medical Center, Kansas City, KS, United States

 
We have overcome the difficulty of measuring blood-brain barrier (BBB) permeability in mice longitudinally by combining T1 mapping and using i.p. administration of Gd-DTPA. We have successfully quantified BBB permeability from the signal changes associated with uptake of Gd-DTPA following traumatic brain injury for 2weeks using T1 map. Results show that significant entry of Gd-DTPA into the brain was evident in the injury site at P3&P7 but almost return to normal level at P14. This study demonstrates that the technique can be employed in longitudinal study of BBB permeability in mice brain in vivo.

 
1526.   Utility of Cardiac Gating for Pulmonary Perfusion MRI 
Kang Wang1, Mark Schiebler2, Christopher Francois2, Alejandro Munoz Del Rio1,2, Frank Korosec1, Sean Fain1, and Scott Nagle2
1Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, 2Radiology, University of Wisconsin-Madison, Madison, WI, United States

 
Cardiac motion is a common source of artifact on MR images of the thorax. Traditionally, ECG-gating has been employed to minimize these artifacts, at the expense of decreased scan efficiency and increased complexity in patient set-up. This trade-off is application-specific, with some imaging techniques more sensitive to cardiac motion artifacts than others. The purpose of this study was to determine whether or not ECG-gating improves image quality for pulmonary perfusion MRI using a recently developed pulmonary perfusion method that results in high isotropic spatial resolution, high temporal resolution, and whole chest coverage.

 
1527.   In vitro skin penetration measurement with contrast-enhanced MRI at 7 Tesla 
Maximilian N Voelker1, Jan M Burg2, Peggy Schlupp3, Ulf Maeder2, Alexander M Koenig1, and Johannes T Heverhagen1
1Diagnostic Radiology, Philipps University Marburg, Marburg, Hessen, Germany, 2Institute of Medical Physics and Radiation Protection, University of Applied Sciences Giessen-Friedberg, Giessen, Germany, 3Institute of Biopharmaceutical Technology, University of Applied Sciences Giessen-Friedberg, Giessen, Germany

 
The penetration of MRI contrast agents into the skin can be measured directly by MRI. With a submicron emulsion as carrier system the efficiency and the dynamics of a Drug Carrier System on the penetration of a topically applied contrast agent can be assessed. Skin penetrating contrast agents could be a new diagnostic tool for the staging of skin tumours or can also be useful as a marker for topically applied drugs

 
1528.   Series expansion of multi-compartment models for DCE-MRI 
Steven Sourbron1
1Division of Medical Physics, University of Leeds, Leeds, United Kingdom

 
A physically intuitive approach is presented for generating approximations to multi-compartment models for DCE-MRI, and illustrated by application to the two-compartment exchange model. Using this method, the analytical solution for arbitrary multi-compartment models can be written out to any desired accuracy simply by listing in order the paths that a tracer particle can follow through the system. The method increases the physical insight into the behaviour of more complicated compartmental models, and will allow more freedom and flexibility in the design of advanced compartment models for particular applications.

 
1529.   Pulsed arterial spin labelling perfusion imaging at 3T: estimating the number of subjects required in common designs of clinical trials 
Kevin Murphy1, Ashley D Harris1, Ana Diukova1, Christopher John Evans1, David J Lythgoe2, Fernando Zelaya2, and Richard G Wise1
1CUBRIC, School of Psychology, Cardiff University, Cardiff, Wales, United Kingdom, 2King’s College London, Institute of Psychiatry, Centre for Neuroimaging Sciences, DeCrespigny Park, Denmark Hill, London, United Kingdom

 
Pulsed ASL is likely to find a place in clinical trials and, in particular, the investigation of the action of pharmaceutical agents on neural activity. This study determines the sample sizes necessary to detect regional changes in CBF in common types of clinical trial design: between groups, a two period crossover and within-session. Power calculations suggest that comparatively small cohorts, for example, 7-15 subjects in a crossover can be used to detect a 15 % increase or decrease in CBF. Such sample sizes make feasible the use of CBF measurements in clinical trials of drugs in small cohorts.

 
1530.   Approximating Water Exchange in vivo in a Rat Model 
Colleen Bailey1,2, Firas Moosvi1,2, and Greg J Stanisz1,2
1Sunnybrook Health Sciences Centre, Toronto, ON, Canada, 2Medical Biophysics, University of Toronto, Toronto, ON, Canada

 
Intracellular-extracellular water exchange is an important marker of apoptotic cell death. In this study, the feasibility of measuring exchange in nude rats was examined. Data from three separate steady-state gadodiamide concentrations and an SPGR sequence with at four flip angles were fit to a two-pool model with exchange. The lower case Greek chi2 value was 55% lower than a similar model with the same number of parameters that assumed fast exchange. The exchange value in muscle, 0.24 ± 0.10 s-1, was consistent with that found in previous studies.

 
1531.   The impact of water exchange on dynamic contrast enhanced MRI: can we estimate tissue water residence times in vivo? 
Lauren Jean Bains1,2, Josephine H Naish1,2, and David L Buckley3
1Imaging Sciences Research Group, University of Manchester, Manchester, Greater Manchester, United Kingdom, 2Biomedical Imaging Institute, Manchester, Greater Manchester, United Kingdom, 3Division of Medical Physics, University of Leeds, Leeds, United Kingdom

 
In this study, a T1 weighted dynamic contrast enhanced (DCE) MRI acquisition with two bolus injections and two flip angles (30° and 5°) was used to create a DCE timecourse with varying sensitivity to water exchange. The results from using a two compartment model of tracer kinetics incorporating water exchange effects (the WX-2CXM) to fit these data showed that the low flip angle portion of the timecourse had significantly greater sensitivity to water exchange than the 30° portion. The acquisition was sufficiently sensitive to water exchange to provide preliminary estimates of the residence times of water in three tissue compartments.

 
1532.   Correction of base-line [Gd] offsets due to effective saturation pulse flip-angle variations in 3T liver DCE-MRI 
Andrew Brian Gill1,2, Andrew N Priest2, Richard T Black1, David J Bowden2, Martin J Graves2, and David J Lomas2
1Medical Physics, Addenbrooke's Hospital, Cambridge, United Kingdom, 2Radiology, University of Cambridge, Cambridge, United Kingdom

 
[Gd] base-line discrepancies in liver DCE-MRI data have been recorded when using a dual acquisition, saturation-prepared fast gradient echo sequence at 3T, recording images in two separate slice orientations in each heartbeat. Pre-contrast discrepancies in [Gd] are thought to be due to flip-angle variation in the saturation pulses. A theoretical correction is derived to estimate the flip-angle at each region of interest and hence determine the true [Gd] curve. Volunteer data has been analysed using a dual-input pharmacokinetic model. Results show correction of the base-line discrepancy, consistent values for pharmacokinetic indices and improved values for the tissue arrival times.

Traditional Posters : Other
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Drug Discovery

 
Thursday May 12th
Exhibition Hall  13:30 - 15:30

1533.   Pharmacological MRI with continuous ASL in conscious rats: characterizing the relationship between CBF response to CNS compounds and plasma concentration levels 
Alexandre Coimbra1, Denise Welsh1, Diane Posavec1, Amy Vanko1, Richard Baumgartner2, Christopher Regan3, Andrew Danziger3, Matthew Baran3, Kristina Groover3, Jacquelynn Cook1, Joseph Lynch3, Jason Uslaner3, and Donald Williams1
1Imaging, Merck & Co, Inc, West Point, PA, United States, 2Biometrics, Merck & Co, Inc, Rahway, NJ, United States, 3Central Pharm, Merck & Co, Inc, West Point, PA

 
Pharmacological functional MRI techniques have been used to assess drug effects in the central nervous system, however little has been done to characterize the relationship between the phMRI pharmacodynamic (PD) response and plasma concentration (pharmacokinetics, PK) of the compound being evaluated. This study aimed at exploring PK/PD relationships of phMRI response to two CNS acting compounds in conscious rats, donepezil and lorazepam using arterial spin labeling (ASL) measurements of CBF. Overall, these results provide insight into CBF PK/PD relationships and suggest potential use of conscious rat ASL as a platform providing translational biomarkers for CNS compound dose selection.

 
1534.   Assessment of DCEMRI with gadoxetate as a biomarker of drug induced cholestasis 
Jose Ulloa1, Simone Stahl2, Neil Woodhouse1, Guy Healing2, Gerry Kenna2, John C Waterton1, and Paul Hockings1
1Translational Sciences, AstraZeneca, Macclesfield, Cheshire, United Kingdom, 2Safety Assessment, AstraZeneca, Macclesfield, Cheshire, United Kingdom

 
DCEMRI with gadoxetate is a suitable biomarker of transient cholestasis. However, its utility for characterising the potential cholestatic effects of investigational new drugs has not yet been established. Our aim was to evaluate DCEMRI biomarkers of drug-induced cholestasis using an investigational chemokine agonist as a model compound. Dose-dependent inhibition of gadoxetate transport into bile indicated the model compound inhibits Mrp2. Inhibition of hepatic uptake suggests competition with gadoxetate for Oatp1 binding. Gadoxetate transport may be a sensitive, specific and translatable marker of transporter function which may aid in drug evaluation and increase patient safety

 
1535.   Antibiotic minocycline suppressess the phMRI response to acute ketamine challenge 
Duncan Jack Hodkinson1, Diana Cash2, Steve C R. Williams2, Shane McKie3, John Francis W. Deakin3, and Steve R Williams1
1Imaging Science & Biomedical Engineering, University of Manchester, Manchester, United Kingdom, 2Neuroimaging Research Group, Institute of Psychiatry, King's College London, London, United Kingdom, 3Neuroscience & Psychiatry Unit, University of Manchester, Manchester, United Kingdom

 
Minocycline is a safe, widely prescribed antibiotic which has beneficial effects against apoptosis, inflammation, and microglial activation. Increasing clinical evidence suggests minocycline improves negative symptoms in schizophrenia if added adjunctively to usual therapy. However, the precise neuropharmacological mechanisms underlying these effects remain to be fully elucidated. Here, we applied pharmacological MRI (phMRI) to investigate the modulatory effects of minocycline on regional BOLD signal changes induced by acute ketamine challenge in the rat brain. Pre-treatment with minocycline (50mg/kg s.c.) produced widespread inhibition of ketamine-induced functional activation. These findings suggest direct involvement of minocycline in modulating glutamate neurotransmission.

 
1536.   In Vivo Target Analysis by MRI in a Murine Model of Pulmonary Fibrosis 
Nicolau Beckmann1, Anna L Babin2, Christelle Gerard1, Catherine Cannet1, Helmut Sparrer3, Pierre Saint-Mezard4, Gabor Jarai5, and Tetsuya Matsuguchi6
1Global Imaging Group, Novartis Institutes for BioMedical Research, Basel, Switzerland, 2Sackler Institute of Pulmonary Pharmacology, Kings College London, London, United Kingdom,3Autoimmune Diseases Department, Novartis Institutes for BioMedical Research, Basel, Switzerland, 4Developmental and Molecular Pathways Department, Novartis Institutes for BioMedical Research, Basel, Switzerland, 5Respiratory Diseases Department, Novartis Institutes for BioMedical Research, Horsham, United Kingdom, 6Department of Developmental Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan

 
Bleomycin-elicited injury is often adopted to investigate in small rodents pathological mechanisms of lung fibrosis and for preclinical evaluation of novel therapies. Here, a long lasting response, up to day 70 following repeated bleomycin dosing, was detected non-invasively by MRI in the lungs of male C57BL/6 mice. Following a biological evaluation, the model was used to investigate two knockout mouse lines with the aim of providing potential therapeutic targets. MRI and histology demonstrated a protection against bleomycin insult in female heterozygous and male homozygous cancer Osaka thyroid kinase knockout animals. In contrast, no protection was seen in cadherin-11 knockout mice.

 
1537.   Cerebral amyloid angiopathy in APP23 mice modelling Alzheimer’s disease studied non-invasively by MRI: Application to passive amyloid-beta immunotherapy 
Nicolau Beckmann1, Christelle Gerard1, Dorothee Abramowski2, Catherine Cannet1, and Matthias Staufenbiel2
1Global Imaging Group, Novartis Institutes for BioMedical Research, Basel, Switzerland, 2Neuroscience Discovery, Novartis Institutes for BioMedical Research, Basel, Switzerland

 
With about 20 antibodies and vaccines currently in clinical trials amyloid-¥â (A¥â) immunotherapy is the most heavily studied novel treatment approach for Alzheimer's disease (AD). Although generally well tolerated A©¬ immunotherapy has been associated with microvascular lesions as indicated clinically by vasogenic edema and histologically by microhemorrhages. In our study we have (i) developed an MRI method based on the administration of superparamagnetic iron oxide (SPIO) nanoparticles to non-invasively study the development of cerebral amyloid angiopathy (CAA) in amyloid precursor protein (APP) transgenic mouse models and (ii) applied the method to a passive A¥â immunotherapy study in APP23 mice.

 
1538.   In vivo MR approaches to validate the capacity of a new vanadium compound as a promising anti-diabetic drug 
Ana Marguerita Martins Metelo1, Rocio Pérez-Carro1, Maria M. C. A. Castro2, and Pilar López-Larrubia1
1Instituto de Investigaciones Biomédicas "Alberto Sols", CSIC/UAM, Madrid, Madrid, Spain, 2Dept. Life Sciences, Faculty of Science and Technology, University of Coimbra, Coimbra, Coimbra, Portugal

 
Diabetes mellitus is a metabolic and chronic disease that affects million people worldwide. As far as we know, it does not exist an available commercial drug to treat efficiently diabetic people. In this work we report for the first time, the use of Magnetic Resonance Imaging and Spectroscopy to show the role of VO(dmpp)2 on lipid metabolism of pre-diabetic rats. Images and 1H spectra acquired in the rat livers during treatment, showed a reversion of pathological conditions. This study not only proves the anti-diabetic capacities of VO(dmpp)2, but it also establishes MRI/MRS approaches as useful techniques in drug’s development.