MRA & Flow of Neurovascular Disease
Exhibit Hall 2-3                    Thursday 13:30-15:30

                  1328.     Consistent Automated Planning of Irregular ROI’s for Intracranial MRA MIP’s

Chiel J. den Harder1, Elizabeth A. Moore1, Arianne M. van Muiswinkel1

1Philips Healthcare, Best, Netherlands

MIP’s of intracranial MRA’s require definition of regions of interest (ROI’s). Drawing ROI’s manually can be tedious and error-prone. Alternatively, using automated segmentation to consistently define ROI’s doesn’t allow for user preferences about shape and position of ROI’s.

                  1329.     Studying the Hemodynamics in Cerebral Arteries Using Image-Based Computational Fluid Dynamics and 4D Phase-Contrast Magnetic Resonance

Juan R. Cebral1, Christopher M. Putman2, Marcus Alley3, Roland Bammer3, Fernando Calamante4,5

1Computational and Data Sciences, George Mason University, Fairfax, VA, USA; 2Interventional Neuroradiology, Inova Fairfax Hospital, Falls Church, VA, USA; 3Department of Radiology, Stanford University, Stanford, CA, USA; 4Brain Research Institite, Florey Neurosciences Institutes (Austin), Melbourne, Victoria, Australia; 5Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia

Studying the hemodynamics in cerebral arteries using image-based computational fluid dynamics and 4D phase-contrast magnetic resonance

                  1330.     A New Method for Selective Dynamic MRI Angiography Using Arterial Spin Labeling

Tom Okell1,2, Matthias Guenther3, David A. Feinberg4, Peter Jezzard1

1FMRIB Centre, University of Oxford, Oxford, Oxon, UK; 2Churchill Hospital, Oxford, Oxon, UK; 3University of Heidelberg, Germany; 4Advanced MRI Technologies, CA, USA

In this study we demonstrate for the first time a new method for non-invasive selective dynamic angiography using the principles of arterial spin labeling (ASL). A pseudo-continuous ASL labeling module was inserted in front of a low flip angle flow-compensated cine angiographic readout module. This allows selective labeling and visualization of the major feeding arteries to the brain, analogous to the invasive alternative method of intra-arterial x-ray digital subtraction angiography. The new method has potential applications in a number of cerebrovascular diseases, such as carotid or vertebral stenosis, arterio-venous malformation, and stroke.

                  1331.     MRI Assessment of Blood Flow Artifacts in a Transgenic Mouse Model of Alzheimer’s Disease

Firat Kara1, Janneke Ravensbergen1, Niels Braakman1, Mark A. van Buchem2, Reinhard Schliebs3, Huub J.M. de Groot1, A Alia1

1Leiden Institute of Chemistry, Leiden University, Leiden, P.O. Box 9502, Netherlands; 2Department of Radiology, Leiden University Medical Center, Leiden, Netherlands; 3Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany

It is well known that vascular abnormalities coexist with other pathological features of Alzheimer’s disease (AD). In this study we applied high resolution MRA at 9.4T to compare the vascular architecture of living APPTg2576 transgenic and control mice. Due to high field strength and use of strong gradients, the large and medium sized arteries were very clearly imaged. Flow voids were observed at different places such as in superior cerebral artery, anterior cerebral arteries as well as in pterygopalatine arteries. Our results suggest that MRA at high magnetic field is useful method to monitor blood flow defect in mouse models of AD.

                  1332.     In Vivo Visualization of Brain Tumour Angiogenesis Using 3D δR2-Based Microscopic MR Angiography (3DδR2-MMRA)

Chien-Yuan Lin1,2, Ming-Huang Lin2, Sui-Shan Lin2, Yu-Ying Tung2, Jyh-Horng Chen1, Chen Chang2

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

Tumor-associated microvascular changes offer important new insight into how tumors grow and respond to treatment. This study was aimed to simultaneously assess the changes of microvascular morphology and function on ethylnitrosourea(ENU)-induced rat brain tumor model at different stages using 3D £GR2-Based Microscopic MR Angiography (3D£GR2-mMRA).

                  1333.     Comparison of Hypercapnia- And Hyperoxia-Induced Blood Flow Changes in the Retina Detected by MRI and Laser Speckle Imaging

Haiying Cheng1, Yumei Yan1, Yingxia Li1, Timothy Q. Duong2

1Yerkes Imaging Center, Emory University, Atlanta, GA, USA; 2Research Imaging Center, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA

We recently reported blood-flow (BF) MRI of the rat retina at 90x90x1500-m;m resolution. We found that hyperoxia decreased blood flow relative to baseline (air) and hypercapnia increased blood flow. BF measurements of physiologic stimuli in the retina are sparse due to a lack of reliable blood flow imaging techniques to study the retina. Available data indicated that hypercapnic responses in the retina are controversial with some reporting no changes and others reported significant changes. To corroborate our MRI findings, we developed and applied a novel laser speckle imaging to measure BF in the rat retina under identical experimental conditions.

                  1334.     4D Velocity Measurements in an Intracranial Aneurysm Using 3T Phase Contrast Angiography

Pim van Ooij1, Joppe J. Schneiders1, Marieke E.S. Sprengers1, Ed van Bavel2, Aart J. Nederveen1, Charles B.L.M. Majoie1

1Radiology, AMC, Amsterdam, Noord - Holland, Netherlands; 2Biomedical Engineering & Physics, AMC, Amsterdam, Noord - Holland, Netherlands

4D velocity measurements using phase contrast angiography can be a useful tool to diagnose patients with neurovascular diseases. In this study velocity in an intracranial aneurysm is measured. The treatment of intracranial aneurysms is invasive and risky, so more knowledge on the factors that contribute to aneurysmal rupture is needed. In this study it is shown that when the aneurysm is large enough, clinically relevant velocity profiles can be measured using phase contrast angiography, which can serve as a validation of computational flow dynamics, or used as boundary conditions.

                  1335.     Assessment of the Neovascularisation of Carotid Atherosclerotic Plaque in Symptomatic Patients at 3T by DCE-MRI: Feasibility Study

N. Jane Taylor1, Vicky J. Goh1, J James Stirling1, Ian Simcock1, Matthew Orton2, David J. Collins2, Ralph Strecker3, Leon Menezes4, Justin Cross5, Carl W. Kotze6, Syed W. Yusuf6, Ashley M. Groves4

1Paul Strickland Scanner Centre, Mount Vernon Hospital, Northwood, Middlesex HA6 2RN, UK; 2CR-UK Clinical MR Research Group, Royal Marsden Hospital, Sutton, Surrey, SM2 5PT, UK; 3Healthcare Sector, Siemens AG, 91052 Erlangen, Germany; 4University College Hospital, London, UK; 5Addenbrookes Hospital, Cambridge, UK; 6Brighton and Sussex University Hospitals, Brighton, UK

The purpose was to prospectively assess the neovascularisation of symptomatic carotid plaques using DCE-MRI at 3T. 9 patients (8 male; mean 71 years) presenting with transient ischaemic attack, with significant stenoses on Doppler ultrasound and awaiting carotid endarterectomy underwent 3T DCE-MRI following injection of 0.1mmol/kg Gd-DTPA (dynamic 3D VIBE sequence, 5.3s interval, 70 acquisitions). Semiquantitative (IAUGC60; peak gadolinium concentration (mmol); time to peak (s), maximal gradient) and quantitative (Ktrans, ve, kep, vp) parameters were obtained following motion correction and image registration. Mean Ktrans, ve, kep were 0.74, 0.28, 2.33 respectively. 3T DCE-MRI plaque assessment is feasible.

                  1336.     The Role of 4D MRA with Keyhole and View-Sharing at 3.0T in the Diagnostic Work-Up of Cerebral Arteriovenous Malformations: A Prospective Intra-Individual Study

Dariusch Reza Hadizadeh1, Guido M. Kukuk1, Jürgen Gieseke1,2, Gabriele Beck3, Liesbeth Geerts3, Julia Bergener1, Azize Boström4, Johannes Schramm4, Horst Urbach1, Hans Heinz Schild1, Winfried Albert Willinek1

1Radiology, University of Bonn, Bonn, NRW, Germany; 2Philips Heathcare, Hamburg, Germany; 3Philips Healthcare, Best, Netherlands; 4Neurosurgery, University of Bonn, Bonn, NRW, Germany

The combination of keyhole, CENTRA, parallel imaging, partial Fourier, and view-sharing allows for high spatial and sub-second temporal resolution 4D MRA with whole head coverage. 4DMRA was evaluated in the entire diagnostic work-up of patients with cerebral arteriovenous malformations (cAVM) including pre- and post-operative assessment and was compared to digital subtraction angiography (DSA) in 38 consecutive patients. Highly accelerated 4DMRA matched with DSA in all patients regarding pre-operative Spetzler-Martin Classification and post-operative residual filling and may be considered a non-invasive alternative in the diagnostic work-up of patients with cAVM.

                  1337.     Quantitative MR Perfusion in Patients with Intracranial Arteriovenous Malformations: Utilizing Spin-Echo Sequences to Characterize Vascular Steal

Christopher Sean Eddleman1, Jessy J. Mouannes2, Anindya Sen3, Guilherme Dabus3, Christopher C. Getch, Bernard R. Bendok3, Hunt H. Batjer, Timothy J. Carroll3

1Neurological Surgery, Northwestern University, Chicago, IL, USA; 2Biomedical Engineering, Northwestern University; 3Radiology, Northwestern University

Intracranial arteriovenous malformations (iAVMs) are high-flow AV shunts that can affect perfusion of surrounding normal brain. Although controversial, vascular steal is thought to contribute to the risk of normal perfusion breakthrough. Knowledge of specific areas of vascular steal could alter endovascular and surgical strategies of treatment. Spin-echo perfusion acquisitions allow detailed mapping of areas of vascular steal in patients with iAVMs.

                  1338.     Evaluation of Blood Flow from STA-MCA Bypass by MRA with Off-Sagittal Saturation Pulse

Toshiaki Akashi1, Toshiaki Taoka1, Hiroyuki Nakagawa1, Toshiteru Miyasaka1, Masahiko Sakamoto1, Satoru Kitano1, Satoru Iwasaki2, Kimihiko Kichikawa1

1Radiology, Nara Medical University, Kashihara, Nara, Japan; 2Radiology, Higashiosaka City General Hospital, Higashiosaka, Osaka, Japan

We evaluated the feasibility of MRA with off-sagittal saturation pulse covering STA and bypass point (sMRA) for discrimination between antegrade flow from ICA and bypassed flow from STA. Conventional MRA (cMRA) and sMRA were obtained. sMRA demonstrates only antegrade flow because off-sagittal saturation pulse suppress signal of bypassed flow while cMRA shows both of antegrade and bypassed flow. Subtracting source images of sMRA from those of cMRA was able to give source images and MIP images demonstrating bypassed flow with suppressed antegrade flow in most cases. sMRA is feasible technique for the post-operative assessment of STA-MCA bypass function.

                  1339.     Evaluation of Perforating Arteries Originating from the Posterior Communicating Artery at 7 Tesla MRI

Mandy M. Conijn1, Jeroen Hendrikse, Jaco J. Zwanenburg2, Taro Takahara, Mirjam I. Geerlings3, Willem P. Mali, Peter R. Luijten2

1Radiology, University Medical Center Utrecht, Utrecht, Netherlands; 2Image Sciences Institute, University Medical Center Utrecht; 3Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht

This is the first study to date that utilized the increased sensitivity of 7 Tesla MRI to study the anatomical variability of small, normally non-detectable, arteries in the brain. With angiography at 7T we could clearly visualize the deep perforating arteries branching from the posterior communicating artery (PCoA) without use of contrast agents. We found a high prevalence of visible perforating arteries branching from the PCoA, and an association between the diameter of the PCoA and the presence of a perforator. Furthermore, we found a significant correlation between the left sided and right sided anatomy of the posterior circulation.

                  1340.     Assessing Cerebrospinal Fluid Flow in the Brain Using 3D Phase Contrast Velocity Encoded MRI

Henrik Odéen1, Michael Markl2, Bruce S. Spottiswoode3

1Lund Institure of Technology, Lund University, Lund, Sweden; 2Diagnostic Radiology, Medical Physics, Albert-Ludwigs Universität, Freiburg, Germany; 3Cape Universities Brain Imaging Centre, Cape Town, South Africa

This work describes the application of 3D velocity encoded MRI to assess CSF flow patency in the brain. Five normal volunteers were scanned using a time-resolved 3D gradient echo phase contrast sequence with 3-directional velocity encoding. Post processing involved spatiotemporal phase unwrapping, fitted field inhomogeneity surface subtraction, and combining data from the three velocity encoding directions into a 3D integrated flow volume. Communicating flow between ventricles and passageways was then identified using nearest-neighbour connectivity. Flow connectivity within the brain was demonstrated in all five volunteers. This technique provides an automated and promising means of assessing CSF flow patency.

                  1341.     Is Flow Rate or Stroke Volume Better for the Assessment of CSF Flow in NPH?

Mario Forjaz Secca1,2

1Cefitec, Physics Department, Universidade Nova de Lisboa, Monte de Caparica, Portugal; 2Ressonancia Magnetica - Caselas, Lisboa, Portugal

Two different parameters have been used in the assessment of abnormality in the flow of CSF at the Aqueduct for NPH (normal pressure hydrocephalus): Stroke Volume and Flow rate, which can lead to contradictory results. Since both can be calculated easily from the same data, we evaluated which would be the best parameter to take into consideration. By analyzing the data from 580 patients and studying of the variation of both values with heart rate on volunteers we found that FR, leading to less abnormal cases and being less sensitive to heart rate, is a better parameter to evaluate NPH

                  1342.     MR Arterial Spin Labeling and Spectroscopy in Patients with Symptomatic Internal Carotid Artery Occlusion

Jie Lu1, Kuncheng Li, Miao zhang

1Xuanwu Hospital, Capital Medical University, Beijing, China

ASL is a non-invasive method to quantitatively measure perfusion without contrast material. MRS can non-invasively identify cerebral abnormal metabolism. Patients with symptomatic occlusion of the internal carotid artery (ICA) with compromised cerebral blood flow (CBF) and decrease N-acetyl aspartate (NAA) are at risk for future ischemic infarcts in the brain. In this study, we characterized CBF and the concentrations of choline, creatine, and NAA changes in cerebral white matter in patients with symptomatic ICA occlusion. Our result suggested ASL and MRS may provide a convenient, inexpensive, noninvasive method for identifying ICA occlusion patients at risk for future stroke.

Novel Experimental & Therapeutic Strategies in Stroke
Exhibit Hall 2-3                    Wednesday 13:30-15:30

                  1343.     Feasibility of Imaging Mesenchymal Stem Cells in Vitro Using Standard MRI Sequences

Emidio Tarulli1, Voytek Gretka2, Amy Hoyles3, Cindi Morshead3, Greg J. Stanisz2

1Department of Medical Biophysics, University of Toronto, Toronto , ON, Canada; 2Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada; 3Department of Surgery, University of Toronto, Toronto, ON, Canada

While stem cell therapies of stroke have shown success in structural and functional recovery of lost tissue, the ability to track cell migration and distribution in a non-invasive manner remains a work in progress. This study demonstrates the ability to track single rat mesenchymal stromal cells (rMSCs) labeled with micron-sized superparamagnetic iron-oxide (MPIO) particles (Bangs Labs, MC05F) with standard MRI sequences in vitro.

                  1344.     Limitations of Iron-Based Stem Cell Tracking in MRI-Monitoring of Stem Cell Therapies in Vivo

Emidio Tarulli1, Voytek Gretka1, Amy Hoyles2, Cindi Morshead2, Greg J. Stanisz1

1Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada; 2Department of Surgery, University of Toronto, Toronto, ON, Canada

This investigation makes use of

                  1345.     Novel Combination Therapy of Recombinant Annexin 2 and Low Dose Recombinant Tissue Plasminogen Activator in Embolic Rat Stroke Model: A Magnetic Resonance Imaging Study

Yoji Tanaka1, Tsukasa Nagaoka1, Govind Nair1, Qiang Shen1,2, Xiaodong Zhang1, Timothy Q. Duong1,2

1Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA; 2Research Imaging Center, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA

In the treatment of acute phase ischemic stroke, tPA has high risk of hemorrhage which is usually fatal, and the treatment time window is very narrow. The aim of this study is to examine a novel combination therapy of recombinant annexin 2 and low dose rtPA for acute ischemic stroke with employing MRI. We conclude that the combination therapy has a possibility to reduce the harmful side effect of rtPA without reducing its benefits as treatment.

                  1346.     Effect of NBO Treatment on Lesion Volume at Early and Late Reperfusion Time Points After Transient Focal Cerebral Ischemia

J Ramu1, W Liu1, KJ Liu1, R Sood1

1Neurology, University of New Mexico, Albuquerque, NM, USA

The goal of this study was to compare the effect of NBO treatment on the lesion volume between early and late reperfusion time points in a rat model of middle cerebral artery occlusion (MCAO).

                  1347.     Aging and Hypertension Increase the Susceptibility of Brain Tissue to Ischemic Injury: Animal Brain MR Imaging Study

MeiYu Yeh1, Tsong-Hai Lee2, Ho-Ling Liu3,4

1Department of Medical Imaging and Radiological Sciences, Chang Gung University,, Kwei-Shan , Tao-Yuan, Taiwan; 2Stroke Section, Department of Neurology and Stroke Center,, Chang Gung Memorial Hospital, Kwei-Shan , Tao-Yuan, Taiwan; 3Department of Medical Imaging and Radiological Sciences, Chang Gung University, Kwei-Shan, Tao-Yuan, Taiwan; 4MRI Center, Chang Gung Memorial Hospital, Kwei-Shan , Taoyuan, Taiwan

Age is the most important non-modifiable risk factor for stroke and it is estimated that the stroke rate is doubled each 10 years after age 55. Diffusion- and perfusion-weighted magnetic resonance imaging (DWI and PWI, respectively) can provide a simple and feasible method to investigate the ischemic brain tissue at risk for infarction in the acute stage of stroke. Our study suggests that the reason for aging and hypertension to be the most significant risk factors for stroke is possible that they may increase the susceptibility of normal brain tissue to ischemic injury by influencing the cerebral diffusion and perfusion.

                  1348.     Temporal MRI Profile of Hermorrhagic Transformation After Embolic Stroke in Spontaneously Hypertensive Rats

Ivo Adriaan Carol Willem Tiebosch1, Annette van der Toorn1, René Zwartbol1, Mark Jacobus Rosalie Joseph Bouts1, Ona Wu2, Rick Michiel Dijkhuizen1

1Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands; 2Athinoula A. Martinos center for biomedical imaging, Massachusetts General Hospital, Charlestown, MA, USA

Thrombolytic treatment after acute ischemic stroke increases risk of hemorrhagic transformation (HT), however, the pathological basis thereof is largely unresolved. We applied multiparametric MRI to assess the temporal profile of pathophysiological processes associated with HT after embolic stroke in spontaneously hypertensive rats. Selective regions within the ischemic lesion displayed HT after 7 days. These regions were characterized by significantly reduced perfusion, increased blood-brain barrier leakage and prolonged T2 within 24 h after stroke. This indicates that multiparametric MRI may provide a powerful tool to assess risk of HT after stroke in treated as well as non-treated subjects.

                  1349.     Multiparametric MRI Correlation with Tissue Outcome in Early Phase of Acute Ischemic Stroke in Rats

Kimmo Jokivarsi1, Yrjö Hiltunen2, Risto Kauppinen3, Olli Gröhn1

1Department of Neurobiology, University of Kuopio, Kuopio, Finland; 2Department of Environmental Science, University of Kuopio, Kuopio, Finland; 3Biomedical NMR Research Center, Dartmouth Medical School, Hanover, NH, USA

We investigated the prediction power of different combinations of MRI parameters in rat middle cerebral artery occlusion model. We show that by using three to four MRI contrasts (including diffusion, T2, T1r and perfusion) in combination, correlation ranging from 0.64 to 0.80 with the histological outcome is achieved. The correlation depends on brain region and age of lesion. Our data suggest that MRI may predict ischemic lesion expansion and fate of tissue at risk of stroke in a clinically useful manner.

                  1350.     Late Stimulation of the Sphenopalatine Ganglion in Ischemic Rats Improves NAA Levels and DWI Characteristics

Amnon Bar-Shir1, Noam Shemesh1, Revital Nossin-Manor2, Yoram Cohen1

1School of Chemistry, Tel Aviv University, Tel Aviv, Israel; 2Diagnostic Imaging, The Hospital for Sick Children, Toronto, ON, Canada

The present study longitudinally examines the effect of SPG-stimulation of ischemic rats on NAA levels, DWI characteristics and behavioral tests. It was found that SPG-stimulation treatment of rats after 2h of t-MCAO, started 18±2h after the induction of stroke, improves NAA levels in the ischemic hemisphere of the treated rats and also prevented deterioration of DI values computed from DWI data, 28 days after t-MCAO. These results were corroborated by behavioral examinations. The fact that treatment was started 18±2h after the t-MCAO shows that electrical SPG-stimulation can potentially extend the therapeutic window for the treatment of ischemic stroke.

                  1351.     Localized 1H  MRS of Mouse Brain in Vivo Reveals Metabolic Markers Predicting the Development of Ischemic Damage

Hongxia Lei1,2, Carole Berthet3, Lorenz Hirt3, Rolf Gruetter1,4

1EPFL, Lausanne, Vaud, Switzerland; 2UNIL, Lausanne, Vaud, Switzerland; 3CHUV, Lausanne, Vaud, Switzerland; 4UNIGE, Geneva, Switzerland

1H MRS of ischemic mouse brains is feasible at high magnetic field and detects substantial metabolic changes in the neurochemical profile. The aim of the present study was to investigate the effect of different degrees of focal ischemic insults on the neurochemical profiles at an early time-point and to identify markers for reduced cerebral perfusion and for irreversible ischemic damage. The results show that the glutamine increase indicates ischemia and probably reflects ischemia induced glutamate release, while the neuronal markers N-acetylaspartate and glutamate are more likely to indicate an irreversible cerebral lesion.

                  1352.     Molecular MRI of Thrombus in a Rat Ischemic Stroke Model

Ritika Uppal1, Ilknur Ay1, Guangping Dai1, Young Ro Kim1, Gregory Sorensen1, Peter Caravan1

1Radiology, Massachusetts General Hospital, Charlestown, MA, USA

Ischemic stroke is a leading cause of morbidity and mortality. The identification of the culprit thrombotic lesion, micro-emboli and the source of the embolus are all critical to patient management. We used a fibrin-targeted Gd based contrast agent (EP-2104R) and MRI to characterize a rat thrombo-embolic stroke model. EP-2104R readily identified thrombi in all animals with high contrast to noise, while animals administered GdDTPA showed no thrombus enhancement. These findings correlated with ex vivo tissue measurements of Gd.

                  1353.     Application of a Modified Quantitative BOLD Approach to Monitor Local Blood Oxygen Saturation in Two Glioma Models and a Stroke Model in Rat

Thomas Christen1,2, Benjamin Lemasson1,3, Nicolas Pannetier1,2, Olivier Detante1,2, Régine Farion1,2, Emmanuelle Grillon1,2, Christoph Segebarth1,2, Chantal Rémy1,2, Emmanuel L. Barbier1,2

1Inserm, U836, Grenoble, F-38043, France; 2Université Joseph Fourier, Grenoble Institut des Neurosciences, UMR-S836, Grenoble, France; 3Oncodesign Biotechnology, Dijon, France

Recently, an in vivo MR approach was introduced to obtain local blood oxygen saturation (lSO2) maps. This study evaluates a modified version of this approach in two rat models: stroke and tumor. Values of lSO2 in the contralateral striatum of rats bearing a brain lesion or in healthy rats are consistent with the literature. The small standard deviation suggests that the proposed lSO2 measurement approach is reproducible. Differences in lSO2 were observed between the two glioma models (C6 and U87-MG) and an increase lSO2 two days after focal brain ischemia, in agreement with a luxury perfusion.

                  1354.     Combined in Vivo MR and Optical Imaging of Stroke Induced Neurogenesis in the Mouse Brain

Tracy Deanne Farr1, Dirk Wiedermann1, Sébastien Couillard-Després2, Luwig Aigner2, Mathias Hoehn1

1In-Vivo NMR Laboratory, Max-Planck Institute for Neurological Research, Cologne, Germany; 2Department of Neurology, University of Regensburg, Germany

The formation of new neurons in the adult brain has generated much interest, and could have an impact on recovery from neurodegenerative disease. Neurogenesis is observed using invasive techniques, but the advent of transgenic animals with imaging reporters for cellular or molecular events is a promising alternative. We used mice with a bioluminescent reporter (luciferase) that is produced in response to upregulation of the doublecortin promoter. We are working to establish an in vivo multi-modal optical imaging and MRI protocol to monitor the extent, location, and timecourse of neurogenesis in these mice. Preliminary results indicate this response changes following ischemia.

                  1355.     High Resolution Diffusion Tensor Imaging of Post-Stroke White Matter Integrity in Ex Vivo Rat Brain

Maurits P.A. van Meer1,2, Willem M. Otte1,2, Kajo van der Marel1, Annette van der Toorn1, J. W. Berkelbach van der Sprenkel2, Rick M. Dijkhuizen1

1Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands; 2Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, Netherlands

DTI may inform on alterations in brain connectivity associated with neuroplasticity. Unbiased whole brain assessment with tract-based spatial statistics analysis (TBSS) was used to determine changes in fractional anisotropy (FA) on high resolution maps of ex vivo post-stroke rat brains. A significant reduction in FA in ipsilesional white matter was detected in 10-weeks post-stroke brains. Ipsi- and contralesional medial corpus callosum showed a significant elevation of FA compared to age-matched controls. These results show that high resolution ex vivo DTI in combination with TBSS analysis allows detailed assessment of degenerative and reorganizational changes in white matter integrity after stroke.

Biophysical Mechanisms
Exhibit Hall 2-3                    Monday 14:00-16:00

                 1356.     The Diffusion Tensor Reveals Gray Matter Architecture

Sune Norhoj Jespersen1, Lindsey A. Leigland2, Anda Cornea3, Christopher David Kroenke2,4

1Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark; 2Department of Behavioral Neuroscience, Oregon Health and Science University, Oregon, USA; 3Oregon National Primate Research Center, Oregon Health and Science University, Oregon, USA; 4Advanced Imaging Research Center, Oregon Health and Science University, OR, USA

                  1357.     The Effect of Axonal “Beading” on Water Diffusion Properties:  a Monte Carlo Simulation of Axonal Degeneration and Its Effects on DTI Contrasts

Jonathan A.D. Farrell1,2, Bennett A. Landman3, Jiangyang Zhang2, Seth Smith1,2, Daniel S. Reich4,5, Peter A. Calabresi5, Peter C. van Zijl1,2

1F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA; 2Neuroscience Section, Division of MR Research, Dept. of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; 3Dept. of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA; 4Division of Neuroradiology, Dept. of Radiology, Johns Hopkins University School of Mediciine, Baltimore, MD, USA; 5Dept. of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA

Axonal degeneration, due to injury or disease, can cause multiple localized dilations (“beading”) of the axonal membrane. The goal of this study was to determine the effect of these morphological changes on diffusion properties measured with DWI. Healthy axons are modeled as cylinders, and degenerating axons are modeled as the union of a cylinder and a sphere of varying radii. Using a Monte Carlo framework, we show that axonal “beading” can cause decreased, non-Gaussian parallel diffusion, and increased perpendicular diffusion. This may aid the interpretation of DWI experiments and advance the development of DTI contrasts specific for axonal injury.

                  1358.     Understanding the Recuded ADC in Stroke Lesions Using Repeated Measurements with Different Diffusion Times

Markus Nilsson1, Jimmy Lätt2, Danielle van Westen2, Stig Holtås2,3, Ronnie Wirestam1, Freddy Ståhlberg1,3, Sara Brockstedt2

1Department of Medical Radiation Physics, Lund University, Lund, Sweden; 2MR Department, Center for Medical Imaging and Physiology, Lund University Hospital, Lund, Sweden; 3Department of Diagnostic Radiology, Lund University, Lund, Sweden

The mechanism behind the reduction of the apparent diffusion coefficient (ADC) in ischaemic stroke is as yet unclear. Effects of water exchange have recently been observed in sub-acute stroke lesions, based on measurements with high b-values and a varied diffusion time. Here we repeated such measurements in two patients, three and ten days after stroke onset. The presence of water exchange was verified. The intracellular signal fraction decreased as the time from the stroke-onset increased and we found indications of different relaxation times in the intra- and extracellular space in the stroke lesions.

                  1359.     Evaluation of the Effect of Exchange on the Diffusion Weighted MR-Signal in Brain White Matter

Els Fieremans1,2, Yves De Deene2,3, Jens H. Jensen1, Joseph A. Helpern1

1Department of Radiology, CBI, New York University School of Medicine, New York, NY, USA; 2Department of Electronics and Information Systems, MEDISIP, Ghent University-IBBT-IBiTech, Ghent, Belgium; 3Department of Radiotherapy and Nuclear Medicine, QMRI, Ghent University, Ghent, Belgium

The origin of the anisotropic diffusion weighted (DW) MR-signal observed in brain white matter (WM) is still not completely understood. In this study, Monte Carlo simulations of diffusion are presented in a geometry imitating the white matter. The effect of exchange between the intracellular and extracellular compartment on the DW MR signal has been evaluated. The results show that the diffusion kurtosis is a good probe for the presence of membranes and is sensitive to changes in permeability. Fitting the kurtosis could reveal new insights in the physiology of cells during pathological states.

                  1360.     Renormalization Group Method: Enhancement of Basser-Sen Model of the Brain White Matter

Oleg P. Posnansky1, N. Jon  Shah1,2

1Institute of Neuroscience and Biophysics 3 - Medicine, Research Centre Juelich, Juelich, Germany; 2Faculty of Medicine, Department of Neurology,  RWTH Aachen University,  JARA, Aachen, Germany

We have developed a renormalization group method in order to explore the effects of a large range of geometrical and physical microparameters on the effective apparent diffusion coefficient. The main element of this method comprises the renormalization of structural parameters from the micro to the millimeter scale of the random multi-component white matter of the brain. Our approach enhances the Basser-Sen model by taking the influence of disorder into the consideration and it allows quantitative investigation of the sensitivity of the apparent diffusion coefficient to the variations of the dominant set of micro-parameters.

                  1361.     A Study on the Validity of the Tortuosity Approximation for Extracellular Diffusion Using Monte Carlo Simulations

Hubert Martinus Fonteijn1, Matt G. Hall1, Daniel C. Alexander1

1Department of Computer Science, Centre for Medical Imaging and Computing, London, UK

Models of extracellular diffusion in biological tissue rely on two assumptions: 1. diffusion is approximately Gaussian for long diffusion times and 2. The relationship between the apparent diffusion coefficient in hindered directions and the free diffusion coefficient is only dependent on the intracellular volume fraction and not on the specific tissue geometry. We have tested these assumptions using Monte Carlo simulations for the diffusion weighted signal using cylinders with gamma-distributed radii. We have found a mono-exponentially decaying signal for only a limited range of b-values. Moreover, the ADC is to some extent related to the distribution of cylinder radii.

                  1362.     Trace Weighting in Double Wave Vector Diffusion Experiments in Vivo

Martin A. Koch1,2, Jürgen Finsterbusch1,2

1Dept. of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; 2Neuroimage Nord, Hamburg - Kiel - Lübeck, Germany

Double wave vector diffusion weighting may represent a new method for assessing microscopic tissue structure. The difference between parallel and anti-parallel orientations of the gradients in two successive diffusion weighting preparations might be used to estimate the mean size of tissue pores. Calculations for short gradient pulses predict for samples with a non-uniform distribution of pore orientations that a rotation-invariant size estimate can be derived from the sum of measurements along three perpendicular orientations. It is investigated whether this holds true for in vivo experiments on brain tissue using a whole body MR system with finite gradient pulse durations.

                  1363.     Assessment of Tissue Properties and T2 Relaxation on ADC Measurements by Numerical Simulation of Water Diffusion

Kevin D. Harkins1, Jean-Phillipe Galons2, Timothy W. Secomb3, Theodore P. Trouard1,2

1Biomedical Engineering, University of Arizona, Tucson, AZ, USA; 2Radiology, University of Arizona, Tucson, AZ, USA; 3Physiology, University of Arizona, Tucson, AZ, USA

The biophysical mechanisms which affect the apparent diffusion coefficient (ADC) have been debated since the initial observation of a drop in ADC following ischemic stroke. A computational model of water diffusion is used to assess the role of intracellular volume fraction (IVF), intracellular diffusion coefficient (Dint), membrane permeability and T2 relaxation on the calculated ADC. Simulations indicate that a 30-50% drop in ADC can be achieved by swelling cells from 80% to 90% IVF when the intracellular T2 was allowed to be lower than extracellular T2. Furthermore, at diffusion times greater than 20 ms, the ADC was virtually independent of Dint.

                  1364.     Validation of Models for the Diffusion Weighted MR Signal in Brain White Matter

Els Fieremans1,2, Yves De Deene2,3, Jens H. Jensen1, Joseph A. Helpern1

1Department of Radiology, CBI, New York University School of Medicine, New York, NY, USA; 2Department of Electronics and Information Systems, MEDISIP, Ghent University-IBBT-IBiTech, Ghent, Belgium; 3Department of Radiotherapy and Nuclear Medicine, QMRI, Ghent University, Ghent, Belgium

The diffusion weighted MR-signal attenuation in brain white matter is not mono-exponential. A bi-exponential model has been proposed since this fits the data well. We have modeled the diffusion weighted MR-signal by Monte Carlo simulations in a fiber geometry similar to brain white matter. Although a bi-exponential model fitted the data very well, the fitted diffusion coefficients and fractions did not converge to the simulated values in the intra- and extracellular space. However, fitting the cumulant expansion form terminated after the Nth order term to the data results in accurate fits for the diffusion coefficient and kurtosis.

                  1365.     Evidence for a Vascular Contribution to the Biexponential Signal Decay as a Function of the B-Value in DWI: A Verification of the IVIM-Model

Andreas Lemke1, Lothar Rudi Schad1, Bram Stieltjes2, Frederik Laun3

1Chair in Computer Assisted Clinical Medicine, University of Heidelberg, Faculty of Medicine, Mannheim, Germany; 2Department of Radiology, German Cancer Research Center, Heidelberg, Germany; 3Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany

DWI of the abdomen was performed using a global suppression of the blood signal to investigate the vascular contribution to the measured ADC and to validate the IVIM-model. The perfusion fraction f and the diffusion coefficient D were extracted from the measured DW-data of five healthy volunteers with and without blood suppression using a biexponential fit. The perfusion fraction f in the suppressed pancreatic and liver tissue decreased significantly (p=0.008), whereas the diffusion coefficient D did not change with suppression (p>0.5). These results verify a vascular contribution to the DWI-measurement at low b-values and validate the IVIM-theory.

                  1366.     q-Space MR Propagator in Partially-Restricted, Axially-Symmetric and Isotropic Environments

Evren Ozarslan1, Cheng Guan Koay, Peter J. Basser

1STBB / LIMB / NICHD, National Institutes of Health, Bethesda, MD, USA

Diffusion may lead to non-symmetric propagators, which can be mapped from the complex-valued MRI signal. Because the true diffusion propagator obeys the reciprocity property, both forward and backward Fourier transforms can be employed, leading to propagators with different meanings. Depending on the geometry, Fourier transform in one direction may provide a more intuitive representation of the geometry than the other. In axially-symmetric and isotropic environments, having one-dimensional data is sufficient to reconstruct higher-dimensional propagators. In these environments, other transforms can be employed, which may make information, otherwise obscured by the one-dimensional Fourier transform, visible.

                  1367.     Analysis of Water Diffusion in White Matter Using a Hydration Layer Model

Elena Olariu1, Ian Cameron1,2

1Physics, Carleton University, Ottawa, Ontario, Canada; 2Diagnostic Imaging , Otawa General Hospital

Diffusion measurements have been made with MRI for many years but an explanation for the observed behavior, in terms of the underlying mechanisms is still illusive. Diffusion decays have frequently been interpreted in terms of a two compartment model with the fast and slow diffusion coefficients associated with extra- and intracellular water, respectively. Unfortunately, the observed signal fractions are not consistent with the true ratio of intra- to extracellular water. Recently, LeBihan has suggested that the two observed components may be associated with free water and hydration water rather than with intra- and extracellular water. It is reasonable to expect that intra- and extracellular hydration water will diffuse more slowly than the rest of the tissue water. The purpose of the research reported here was to investigate this suggestion to see if the predictions of this model are consistent with measured diffusion decay data.

                  1368.     Treatment Response of Non-Monoexponential Diffusion in a Glioma Rodent Model

Benjamin Hoff1, Denis Le Bihan2, Alnawaz Rehemtulla3, Thomas Chenevert1, Brian Ross1, Craig Galbán1

1Radiology, University of Michigan, Ann Arbor, MI, USA; 2NeuroSpin, CEA, Saclay, France; 3Radiation Oncology, University of Michigan, Ann Arbor, MI

Diffusion MRI at low b-values (~1000 s/mm2) has shown promise as an early surrogate biomarker of treatment response in glioma patients. Recent studies have shown that at higher b-values (>3000 s/mm2) signal attenuation by diffusion deviates from monoexponential behavior in biological tissue. The aim of this study was to test the response of the apparent diffusion coefficient (ADC) calculated from various non-monoexponential models against a conventional two-point low b-value method following chemotherapy in a rodent brain tumor model.

                  1369.     Dependence of Fractional Order Diffusion Model Parameters on Diffusion Time

Xiaohong Joe Zhou1,2, Qing Gao1,3, Girish Srinivasan1,3, Richard L. Magin3

1Center for MR Research, Univ. of Illinois Medical Center, Chicago, IL, USA; 2Departments of Radiology, Neurosurgery, and Bioengineering, Univ. of Illinois Medical Center, Chicago, IL, USA; 3Dept. of Bioengineering, University of Illinois - Chicago, Chicago, IL, USA

In fractional order diffusion model, anomalous diffusion is described by two new parameters: fractional order spatial derivative â and a spatial variable µ. Although a correlation has been suggested between these parameters and the degree of tissue heterogeneity, the biophysical basis of such correlation has not been established. In this study, we have investigated the effects of diffusion time on these parameters and observed a strong dependence of µ on diffusion time. This result suggests that µ may reflect the degree of diffusion restriction and help establish the interrelation with tissue microstructures.

                  1370.     Diffusion Diffraction Patterns in Different Cells

Davide Imperati1,2, M. Cross3, Klaus Kruttwig1, P. Galvosas4, Konstantin Ulrich4, Andrè Pampel5, Jörg Kärger4, Mathias Hoehn1, Harald E. Möller5, Marc Tittgemeyer1

1Max-Plank Institute for Neurological Research, Cologne, Germany; 2Department of Computer Science, University of Milan, Milan, Italy; 3Interdisciplinary Center for Medical Research, Leipzig, Germany; 4Department of Physics, University of Leipzig, Leipzig, Germany; 5Max-Plank Institute for Cognition and Brain Science, Leipzig, Germany

Diffusion imaging enables microscopic assessment of tissue microstructures by measuring the displacement of water protons.

Diffusion: Pulse Sequences & Sampling
Exhibit Hall 2-3                    Tuesday 13:30-15:30

                  1371.     Preliminary Experiences with Implementing High Resolution CSF-Suppressed Optic Nerve DTI at 3.0T with and Without Parallel Imaging

Rebecca Sara Samson1, Mark R. Symms2, David L. Thomas3, Madhan Kolappan1, David H. Miller1, Claudia A M Wheeler-Kingshott1

1Department of Neuroinflammation, UCL Institute of Neurology, London, UK; 2Department of Clinical & Experimental Epilepsy, UCL Institute of Neurology, London, UK; 3Medical Physics & Bioengineering, UCL, London, UK

There are several technical challenges associated with studying the optic nerve (ON) using DTI, in particular its small size, motion, contamination of signal by fat and Cerebrospinal Fluid (CSF), and susceptibility effects pose significant problems. We present our preliminary experiences with the implementation of ON DTI on two different manufacturer’s 3.0T scanners using different data acquisition methods both with and without the use of parallel imaging.

                  1372.     Improvement of DTI Measurement Using the Composite Gradient Systems on a Clinical 3T MRI System: DTI Study of Ex Vivo Dog's Heart

Seong-Eun Kim1, K Craig Goodrich1, Sung M. Moon1, J. Rock Hadley1, Dennis L. Parker1

1UCAIR Department of Radiology, University of Utah, Salt Lake City, UT, USA

Our composite system has the distinct advantage that both of standard and insert gradient systems can be operated simultaneously and/or independently. With simultaneous acquisition, the gradient strength available from either system alone can be increased. Ihe composite gradient system can acquire better DTI measurements with less artifact in human studies than can be obtained with insert or body gradient coils alone. It can also provide high resolution fMRI datasets with better imaging quality compared to data obtained using the standard gradient system.

                  1373.     Accelerating Diffusion Tensor Imaging Using Multi-Reference Image Constrained Reconstruction

Lindsey Jean Healy1, Osama Abdullah1, Edward W. Hsu1

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

MR diffusion tensor imaging (DTI) has suffered from long scan times, low SNR and resolution. This study examines the accuracy and efficiency of selected schemes to accelerate DTI via reduced encoding and multi-reference constrained reconstruction. Results indicate that generalized-series constrained reconstruction combined with direction-dependent, model-estimated images as references can be used to further improve DTI acquisition efficiency than that achieved previously using a single reference image. The findings support the validity of applying reduced sampling and constrained reconstruction to accelerate DTI, and are particularly promising for 3D DTI, high angular-resolution diffusion imaging, or other experiments that require extremely large datasets.

                  1374.     High b-Value Acquisition Using CURVE-Ball DTI

Sharon Peled1, Stephen Whalen2, Alexandra Golby2

1Radiology, Brigham and Women's Hospital, Boston, MA, USA; 2Neurosurgery, Brigham and Women's Hospital

A new strategy for obtaining high SNR high b-value DTI information in brain is presented. The basis for the approach is the independence of DTI eigenvector directions from the b-value at which the acquisition takes place. This allows determination of the eigenvectors from relatively low b-value DTI. Thus with the help of an appropriate diffusion model, diffusion curves for each eigenvector can be generated using only sparse sampling of high b-value data. The method will enable better diffusion-based tissue characterization in clinical and research settings where scan time is a limiting factor.

                  1375.     Apparent Diffusion Coefficient Measurement of in Vivo Atherosclerotic Plaque Obtained from Six Human Subjects Using 2D Ss IMIV DWEPI Technique on 3T System

Seong-Eun Kim1, Eun-Kee Jeong1, J. Rock Hadley1, John A. Roberts1, Gernald A. Trieman2,3, Laura C. Bell1, Dennis L. Parker1

1UCAIR Department of Radiology, University of Utah, Salt Lake City, UT, USA; 2Surgical Service, VA Salt Lake City Health Care System; 3Department of Surgery School of Medicine, University of Utah

In this work we present the in vivo ADC measurement of in vivo atherosclerotic plaque obtained from six human subjects. The results obtained indicate that ADC map may be of substantial value as a new contrast for carotid plaque imaging. Although our ADC values obtained using the 2D ss IMIV DWEPI technique fall within the range of previously reported ADC value in an ex-vivo study, there is no previously known ADC value of each plaque component from an in-vivo study. The technique demonstrated here can now be used to further investigate the ADC in all types of plaque components.

                  1376.     Parallel Line Scan Diffusion Imaging with 2D Acceleration

Renxin Chu1, Bruno Madore1, Lawrence P. Panych1, Mohammed H. Aljallad1, Stephan E. Maier1

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

Line scan diffusion imaging (LSDI) is a one-dimensional Fourier encoding techniques that typically does not involve phase encoding. The absence of phase encoding provides considerable robustness against motion and immunity from artifacts caused by field inhomogeneities and susceptibility. We propose a novel parallel line scan diffusion imaging with 2D acceleration technique by modulating the 90° and 180° slice selection pulses with a cosine waveform to yield double column excitation in 2D simultaneously. Four-fold acceleration can be achieved, at no cost in SNR. Human brain imaging was carried out to test the technique. The proposed accelerated technique preserves the significant advantages of line scan diffusion imaging, more specifically, immunity from susceptibility-induced signal loses and geometric image distortions.

                  1377.     Measuring and Correcting Errors That Occur in Diffusion Weighted Images Due to Non-Ideal Gradient Linearity

Zoltan Nagy1, Daniel C. Alexander2, Nikolaus Weiskopf1

1Wellcome Trust Centre for Neuroimaging, University College London, London, UK; 2Center for Medical Image Computing, University College London, London, UK

Because the diffusion weighting depends on the gradient amplitude to the second power, any deviations from the linearity in the gradient systems are amplified in ADC images. However, if this deviation in the gradient amplitude is known for each voxel the diffusion weighting b-value can be corrected, giving the accurate ADC measurement in every voxel. We provided a simple method of estimating the errors due to each of the diffusion encoding gradients and a simple formula for voxelwise correction of the ADC images.

                  1378.     Feasibility of In-Vivo Diffusion Tensor Echo Planar Imaging and Fiber Tracking at 14.1T

Nicolas Kunz1,2, Yohan van de Looij1,2, Petra S. Hüppi2, Stéphane V. Sizonenko2, Rolf Gruetter1,3

1Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; 2Division of Child Growth & Development, Department of Pediatrics, University of Geneva, Geneva, Switzerland; 3Department of Radiology, University of Geneva and Lausanne, Geneva and Lausanne, Switzerland

Despite the high interest of combination of DTI and MRS at ultra-high magnetic field, none such multimodal in vivo studies in the rodent brain have been published. This combination is very challenging due to different requirements of the two modalities. High resolution MRS requires the use of a transceive surface coil. The aim of this study was to implement a DTI-EPI sequence with whole brain coverage at 14.1T, while using a surface coil as both transmitter and receiver. We demonstrate the feasibility of in vivo DTI-EPI at 14.1T using a transceive surface coil with whole brain coverage.

                  1379.     Comparison of Reduced-FOV Single-Shot EPI Methods for DWI: ZOOM-EPI Vs. 2D Echo-Planar RF Excitation

Emine Ulku Saritas1, Ken-Pin Hwang2, Eric T. Han3, Jin Hyung Lee1, Dwight George Nishimura1, Ajit Shankaranarayanan3

1Department of Electrical Engineering, Stanford University, Stanford, CA, USA; 2Applied Science Laboratory, GE Healthcare, Houston, TX, USA; 3Global Applied Science Laboratory, GE Healthcare, Menlo Park, CA, USA

Single-shot EPI (ss-EPI) is still the most widely used DWI sequence, due to its robustness against motion-induced phase perturbations. However, it is challenging to produce high-resolution diffusion images using ss-EPI. Several reduced-FOV methods have recently been proposed to overcome this challenge. In this work, we compare two of these methods: Reduced-FOV with 2D echo-planar RF (2D-EPRF) excitation and ZOOM-EPI. To achieve a thorough comparison, we present in vivo sagittal and axial DWI of the spinal cord using both techniques.

                  1380.     Double-Spin-Echo Diffusion Weighting with a Modified Eddy-Current Adjustment

Jürgen Finsterbusch1,2

1Dept. of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; 2Neurimage Nord, Hamburg-Kiel-Lübeck, Germany

Echo-planar imaging suffers from geometric distortions in the presence of eddy currents which in particular are prominent after applying diffusion-weighting gradient pulses. To reduce these eddy currents, a double-spin-echo preparation is commonly used where the four pulse durations are adjusted to null eddy currents of a given time constant. However, eddy currents with different time constants are usually present yielding residual geometric distortions. It is shown that these residual distortions can be reduced when adjusting the two gradient pairs to different time constants. Although none of the time constants is compensated completely, the overall eddy-current performance can be improved.

                  1381.     K-Space and Image Space Combination for Motion-Induced Phase Error Correction in 3D Diffusion-Weighted Imaging

Anh Tu Van1, Dimitrios C. Karampinos2,3, Bradley P. Sutton1,4

1Electrical and Computer Engineering, University of Illinois, Urbana, IL, USA; 2Mechanical Science and Engineering, University of Illinois, Urbana, IL, USA; 3Beckman Institute, University of Illinois, Urbana, IL, USA; 4Bioengineering, University of Illinois, Urbana, IL, USA

3D diffusion-weighted imaging (DWI) is highly desirable when high-resolution isotropic voxels are needed in diffusion tensor imaging. However, 3D DWI is prone to motion-induced phase errors, much more than the 2D DWI case. In this work, we extend a previously developed method for motion-induced phase error correction to 3D DWI data. Based on a simple 3D acquisition strategy and rigid-body motion model for the motion-induced phase errors, the new method is time efficient. Both simulation and in vivo experiments are performed to demonstrate the robustness and effectiveness of the proposed method.

                  1382.     Hadamard Slice Encoding for Reduced-FOV Single-Shot Diffusion-Weighted EPI

Emine Ulku Saritas1, Ajit Shankaranarayanan2, Dwight George Nishimura1

1Department of Electrical Engineering, Stanford University, Stanford, CA, USA; 2Global Applied Science Laboratory, GE Healthcare, Menlo Park, CA, USA

A reduced-FOV single-shot EPI method that uses a 90o 2D echo-planar RF excitation has recently been proposed to achieve high-resolution DWI. This method is compatible with contiguous multi-slice imaging without the need for slice skip. However, there is a limit on the number of slices that can be imaged in a simultaneously, determined by the number of slices that can fit between the two adjacent sidelobes of the periodic 2D excitation profile. In this work, we present two different Hadamard slice encoding schemes to double the number of slices for the reduced-FOV method. Specifically, the refocusing 180o RF pulse used to achieve Hadamard slice encoding can be applied either on the two adjacent sidelobes, or on the main lobe of the 2D excitation profile.

Diffusion: Q-Space & Higher Order Approaches
Exhibit Hall 2-3                    Wednesday 13:30-15:30

                1383.     Pearson Set of Distributions as Improved Signal Model for Diffusion Kurtosis Imaging

Dirk H. J. Poot1, Arjan J. den Dekker2, Jan Sijbers1

1Visionlab, University of Antwerp, Antwerp, Belgium; 2Delft Center for Systems and Control, TUDelft, Delft, Netherlands

This work explains a new model which includes the kurtosis of the diffusion process in the model of the recorded diffusion weighted images. This new model is based on the Pearson set of statistical distributions. Compared to the traditional Taylor approximation based model of the diffusion weighted images, this model provides more realistic and accurate predictions of the magnitude of the diffusion weighted images, especially for large b-values. To be able to estimate the kurtosis, these large b-values are needed. Therefore, this improved model is relevant for the estimation of kurtosis measures from diffusion weighted images.

                  1384.     Importance of Multiscale Analysis in HARDI Studies

Irina Kezele1, Cyril Poupon1, Maxime Descoteaux1, Fabrice Poupon1, Jean-François Mangin1

1NeuroSpin, CEA, Saclay, France

High angular resolution distribution diffusion imaging (HARDI) implicitly captures information about the structure in which the diffusion process takes place. HARDI allows examination of relatively wide range of diffusion signal angular frequencies that, due to the complexity of both diffusion process and its milieu, may spread over multiple bands. In consequence, we opt for multiscale analysis, probing all frequencies, but also favouring those frequencies that are more in concordance with our specific aims, which are to deduce and sharpen fibre distributions. Inherent HARDI signal sphericity motivated us to take on the concepts of multiscale spherical wavelet analysis. We show the importance of multiscale signal analysis, and how different angular frequency bands may capture complementary information on underlying fibre distribution.

                  1385.     Groupwise Non-Rigid Registration of 4th-Order Diffusion Tensor Fields and Atlas Construction

Angelos Barmpoutis1, Baba C. Vemuri1, Dena Howland2, John R. Forder3

1CISE, University of Florida, Gainesville, FL, USA; 2Neuroscience, University of Florida, Gainesville, FL, USA; 3Radiology, University of Florida, Gainesville, FL, USA

In this work we present a method for simultaneous groupwise non-rigid registration of 4th-order tensor fields and atlas construction. To achieve the task of registration, we first define a novel distance measure on 4th order tensors using the Riemannian metric of positive real numbers. This metric is employed in an unbiased cost function, that is being minimized in order to estimate the unknown deformation fields and at the same time construct the unknown 4th-order tensor field atlas. We demonstrate the method using DW-MRI datasets from three rat spinal cords.

                  1386.     A Comparison of Two Models of Anomalous DWI Based on a Known Distribution of Water Diffusion Rates

CHU-YU LEE1, Kevin M. Bennett2, Lina J. Karam1, Joseph P. Debbins3

1Department of Electrical Engineering, Arizona State University, Tempe, AZ, USA; 2Harrington Department of Bioengineering, Arizona State University, Tempe, AZ, USA; 3Keller Center for Imaging Innovation, Barrow Neurological Institute, Phoenix, AZ, USA

Sretched exponential (£\DWI) and second-order cumulant (DKI) models were developed to describe the non-monoexponential signal attenuation of a DWI experiment. Both £\ and Kapp are thought to reflect heterogeneity in water diffusion rates, but their relationship to the underlying biophysics is still unclear. In this work, we simulated a simplified physical system of either one or two water compartments with a known distribution of water diffusion rates, and studied how these two models behaved. Our results showed that £\ is directly related to var[D] in both the one- and two-compartment models. Kapp is sensitive to both to E[D] and var[D]. Besides, £\DWI may be preferred when high b-values can be used, but DKI may be preferred at low b-values. However, because DKI is limited to low b-value ranges, it may be insensitive to changes in slow diffusion. These two models are thus similar, but have separate relationships to the intravoxel distribution of water diffusion rates.

                  1387.     Non-Rigid Registration of Diffusion Weighted Images Using Fibre Orientation Distributions

David Raffelt1,2, J-Donald Tournier3,4, Jurgen Fripp5, Natasha Lepore6, Stuart Crozier2, Alan Connelly3,4, Olivier Salvado1

1The Australian E-Health Research Centre, CSIRO, Brisbane, QLD, Australia; 2Department of Biomedical Engineering, University of Queensland, Brisbane, QLD, Australia; 3Brain Research Institute, Florey Neuroscience Institutes (Austin), Melbourne, VIC, Australia; 4Department of Medicine, University of Melbourne, Melbourne, VIC, Australia; 5The Australian E-Health Research Centre, CSIRO,, Brisbane, QLD, Australia; 6Laboratory of Neuro Imaging, David Geffen School of  Medicine UCLA, Los Angeles, CA, USA

Fibre Orientation Distributions (FODs) obtained from diffusion weighted imaging (DWI) provide a non-invasive method to investigate white matter structure and connectivity. In order to compare white matter between individuals, spatial normalisation is required. We propose a free form deformation registration method using a novel similarity measure that optimises directly on FODs. Our technique compared favourably with existing T1 weighted and fractional anisotropy based methods: average images were sharper indicative of more accurate spatial alignment. Unlike existing scalar or diffusion tensor based techniques, this method exploits information provided by FODs in voxels with crossing fibres, independently of how FOD are computed.

                  1388.     Spatial Transformations of Fiber Orientation Fields

Rafael Alonso Clarke1,2, Giovanna Rizzo3, Daniela Perani4, Giuseppe Scotti2, Ferruccio Fazio1,3, Paola Scifo1,2

1Nuclear Medicine, San Raffaele Scientific Institute, Milan, -, Italy; 2CERMAC, San Raffaele Scientific Institute, Milan, -, Italy; 3IBFM, CNR, Milan, -, Italy; 4Università Vita-Salute San Raffaele, Milan, -, Italy

To perform group-level analyses and compare subjects, due to differences in brain shape and size, geometrical transformations must be applied to images to overlap regions.For DTI, the directional information can be considered in transformations using the Preserve Principal Directions method.In this work we present a novel method that we call Preservation of Principal Branches, for the transformation of Fiber Orientation Distribution objects (FODs) that takes into account their specific shapes.

                  1389.     A Polynomial Based Approach to Extract Fiber Directions from the ODF and Its Experimental Validation

Aurobrata Ghosh1, Elias Tsigaridas2, Maxime Descoteaux3, Rachid Deriche4

1Project Odyssée, INRIA Sophia Antipolis Méditerranée, Sophia Antipolis, Alpes Maritimes, France; 2Project GALAAD, INRIA Sophia Antipolis Méditerranée, France; 3NMR Lab, Neurospin / CEA, Saclay, France; 4Project Odyssée, INRIA Sophia Antipolis Méditerranée, France

This paper presents a polynomial based approach for extracting the maximal directions of a spherical function, for example the ODF. It rewrites the ODF in the homogeneous polynomial (HP) basis constrained to the sphere and solves a constrained optimization problem algebraically. This guarantees that all the maxima are computed at once and also provides a measure for the quality of the maxima estimation. Since it works with a continuous polynomial function, this approach is not dependent on a discrete mesh for the mesh-resolution and mesh-orientation. The approach is tested on synthetic, phantom and real datasets and compared to a discrete mesh search approach. It is shown how this HP method naturally overcomes the inherent limitations of the discrete search method.

                  1390.     Estimation of Cell Size Using the Composite Hindered and Restricted Model of Diffusion

Yaniv Sagi1, Peter J. Basser2, Yaniv Assaf1

1Department of Neurobiology, Tel Aviv University, Tel Aviv, Israel; 2Eunice Kennedy Shriver National Institute of Child Health and Human Development, The National Institutes of Health, Bethesda, MD, USA

In this work we used diffusion imaging to estimate the average size of cells in a culture. Two cell cultures differing in cell size were scanned. The signal decay appears to be multi-exponential, indicating multi-compartmetation or restricted diffusion. The signal was fitted to a model of diffusion in two compartments: a hindered, extra-cellular compartment and a restricted, intra-cellular compartment. This enabled us to estimate the mean size of cells in each culture and the volume fractions of intra- vs. extra-cellular matrices. The results are in agreement with known sizes of these types of cells.

                  1391.     Diffusion Propagator Imaging (DPI): An Alternative to Diffusion Spectrum Imaging (DSI)

Maxime Descoteaux1, Kuan-Hung Cho2, Yi-Ping Chao3, Chun-Hung Yeh3, Jean-François Mangin1, Ching-Po Lin3, Cyril Poupon1

1NeuroSpin, IFR 49, CEA Saclay, Gif-sur-Yvette, France; 2National Taiwan University, Taiwan; 3National Yang-Ming University, Taiwan

We propose an alternative to diffusion spectrum imaging called diffusion propagator imaging (DPI). DPI can reconstruct the diffusion propagator from only two spherical shells and around 100 diffusion measurements. The DPI solution is analytical, efficient and compact.

                  1392.     Using Spatial Priors for Better Reconstruction of Fiber Orientation Function in Diffusion MRI

Ashish Raj1, Christopher Hess2, Pratik Mukherjee2

1Radiology, Weill Medical College of Cornell University, New York, NY, USA; 2Radiology, UCSF, San Francisco, CA, USA

MR Diffusion Imaging is an important noninvasive method for probing the white matter connectivity of the human brain. Current methods such as diffusion tensor imaging (DTI), high angular resolution diffusion imaging (HARDI), and diffusion spectrum imaging (DSI) are limited by low spatial resolution, long scan times, and low signal-to-noise ratio (SNR). These methods perform reconstruction on a voxel-by-voxel level, effectively discarding the natural coherence of the data at different points in space. We propose a Bayesian reconstruction to exploit a priori constraints about the smoothly varying orientation structure of white matter tracts over 3D space, and thereby improve their spatial resolution and noise tolerance.

                  1393.     Computed Tomographic (CT) Reconstruction of the Average Propagator from Diffusion Weighted MR Data

Wolfram R. Jarisch1, Evren Özarslan2, Peter J. Basser

1Cyber Technology, Potomac, MD, USA; 2NICHD, NIH, Bethesda, MD, USA

We propose a new method for computed tomography (CT) reconstruction of the entire 3-D Average Propagator, P(r), from diffusion-weighted (DW) MRI data. It entails recognizing that the central slice theorem relates an oblique planar slice of the DWI data in q-space and the corresponding 2-D marginal distribution (projection) of P(r) in r-space. Economy in the CT reconstruction is achieved by employing High-Efficiency CT (HECT), a new CT reconstruction method based on an approximation to Bayes maximum a posteriori (MAP) estimation, along with a priori information, and an optimized experimental design. Our goal is to reconstruct P(r) using approximately 256 DWIs.

                  1394.     Optimizing the Diffusion Weighting Gradients for Diffusion-Kurtosis Imaging

Dirk H. J. Poot1, Arjan J. den Dekker2, Marleen Verhoye3, Ines Blockx3, Johan Van Audekerke3, Annemie Van Der Linden3, Jan Sijbers1

1Visionlab, University of Antwerp, Antwerp, Belgium; 2Delft Center for Systems and Control, TUDelft, Delft, Netherlands; 3Bio-Imaging Lab, University of Antwerp, Antwerp, Belgium

A problem in diffusion kurtosis estimation is the large number of diffusion weighted images that need to be recorded for reliable kurtosis estimates. By optimizing the individual gradient directions and strengths with which the diffusion weighted images are recorded, the precision of kurtosis measures can be maximized for any number of diffusion weighted images, or, alternatively, the number of diffusion weighted images can be minimized for a given precision. This work proposes a method to optimize the set of gradient directions and strengths of diffusion weighted images, by minimizing the Cramér-Rao-lower-bound of a kurtosis measure.

                  1395.     Regularized Q-Ball Reconstruction: Robust  Estimation, Model Selection, and Spatial Denoising

Jaime E. Cisternas1, Pedro Daza1, Takeshi Asahi2, Tim B. Dyrby3, Klaus Fritzsche4

1Engineering School, Universidad de los Andes, Santiago, RM, Chile; 2Center for Mathematical Modelling, Universidad de Chile, Santiago, Chile; 3Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark; 4Division of Medical and Biological Informatics, German Cancer Research Center (DKFZ), Heidelberg, Germany

Diffusion weighted MRI offers the possibility of measuring the random motion of water molecules, revealing important microscopic features of anisotropic tissue such as the orientation of white matter fiber tracts. For high angular resolution acquisitions, recently proposed methods such as Q-ball describe the directional heterogeneity of complex voxels and should in principle detect fiber crossings. Now the Q-ball model, in its different implementations, has a large number of degrees of freedom that are difficult to estimate in the presence of noise, leading to overfitting and artefacts. The present work proposes a variational framework for the estimation, spatial smoothing and model selection, that greatly reduces the impact of noise on the estimated parameters and on other quantities such as the principal and secondary diffusion orientations. Some of the key ingredients of the approach are the use of an expansion in terms of real spherical harmonics to describe the orientation distribution, and a rotationally invariant metric of the coefficients of the expansion.

                  1396.     Simple Harmonic Oscillator Based Reconstruction and Estimation for Three-Dimensional Q-Space MRI

Evren Ozarslan1, Cheng Guan Koay1, Timothy M. Shepherd2, Stephen J. Blackband3, Peter J. Basser1

1STBB / NICHD, National Institutes of Health, Bethesda, MD, USA; 2University of California, San Francisco; 3University of Florida

We present an analytical representation of the three-dimensional q-space signal as a series of eigenfunctions of the 3D simple harmonic oscillator operator in spherical coordinates. The estimation problem lends itself naturally to a convex quadratic programming problem where we impose inequality constraints ensuring the positivity of the probabilities. The reconstruction of the average propagator is immediate once the estimation is performed. The results on human hippocampus data suggest that the technique is practical and robust.

                  1397.     Axon Radius Estimation Using Optimised Stejskal–Tanner and Dual Spin-Echo Sequences at Modest SNR

Jonathan D. Clayden1, Zoltan Nagy2, Daniel C. Alexander3, Chris A. Clark1

1Institute of Child Health, University College London, London, England, UK; 2Wellcome Trust Centre for Neuroimaging, University College London, London, England, UK; 3Department of Computer Science, University College London, London, England, UK

This work describes a process for optimising both Stejskal-Tanner and dual spin-echo diffusion weighted EPI sequences, for the specific purpose of estimating axon radius or other microstructural properties of white matter. The dual spin-echo sequence is optimised with and without eddy-current nulling. We compare the sequences' suitabilities for estimating axon radius, and demonstrate their ability to recover radius information, even with modest gradient strength and SNR.

                  1398.     NEX or No NEX? a High Angular Resolution Diffusion Imaging Study

Maxime Descoteaux1, Nicolas Wiest-Daesslé2, Sylvain Prima2, Christian Barillot2, Rachid Deriche3, Cyril Poupon1

1NeuroSpin, IFR 49, CEA Saclay, Gif-sur-Yvette, France; 2VISAGES Projet, INRIA, Rennes, France; 3Odyssee Projet, INRIA, Sophia Antipolis, France

The need for multiple NEX and averaging along each diffusion gradient direction is shown to be unnecessary. This can significantly reduce acquisition time. We show that a proper filtering of the diffusion measurements correcting the Rician noise bias can increase the quality and coherence of HARDI reconstructions and anisotropy maps while preserving the angular resolution of the reconstruction method.

                  1399.     An Open Source Monte Carlo Framework for Simulating Diffusion in Biologically Relevant Geometries Including Broken, Crimped and Bulging Axons

Bennett Allan Landman1, Jonathan A. Farrell2,3, Peter C. van Zijl2,3

1Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA; 2Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; 3F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA

Diffusion-weighted MRI techniques provide contrasts sensitive to tissue micro-architecture, but current derived-contrasts are non-specific for white matter pathologies. Significant efforts are underway to enhance inference of micro-architecture, and computational models are essential. Previous simulations were largely limited to cylinders and spheres. We present an efficient and flexible framework for simulating diffusion in arbitrary, 3-D compartments and demonstrate our approach by comparing diffusion in healthy, broken, crimped, and bulging axons. This open-source framework enables quantitative comparison of diffusion in biologically relevant restriction geometries which are not analytically accessible and provides a basis for developing and testing higher order diffusion model methods.

                  1400.     Millimeter Analytical Q-Ball Fiber Density Function for a Better Separation of Fiber Populations at 7T

Cyril Poupon1,2, Christopher J. Wiggins1,2, Maxime Descoteaux1,2, Thorsten Feiweier3, Jean-François Mangin1,2, Denis Le Bihan1,2

1CEA NeuroSpin, Gif-sur-Yvette, France; 2IFR 49, Gif-sur-Yvette, France; 3Siemens AG, Erlangen, Germany

The purpose of this work was to demonstrate the feasibility of diffusion-weighted imaging at ultra-high field (7T) with a true millimeter resolution within a reasonable acquisition time. We also demonstrate the possibility of using b-values for performing high angular resolution diffusion imaging (HARDI) such as Q-ball imaging. The results show that high resolution structural organization of the fibers can be revealed with such millimeter data that could not be easily extracted from standard 2mm isotropic data at lower 1.5T or 3.0T fields

                  1401.     Using a Mixture of Watson Distributions to Estimate Intrinsic Fiber Diffusion Properties

Ha-Kyu Jeong1,2, John C. Gore1,2, Adam W. Anderson1,2

1Vanderbilt University Institute of Imaging Science (VUIIS), Vanderbilt University, Nashville, TN, USA; 2Department of Radiology, Vanderbilt University, Nashville, TN, USA

In this study, we derived an analytical relationship demonstrating that the spherical deconvolution representation of diffusion weighted signal can be modeled using a Watson directional distribution model. Using a mixture of Watson distributions, we showed that individual fiber orientations, volume fractions and radial diffusivities can be estimated and visualized. Also, the dominance of one fiber bundle over the other fiber appears clearer when considering estimates of fiber volume fraction and radial diffusivity.

                  1402.     Fanning and Bending Sub-Voxel Structures in Diffusion MRI

Shahrum Nedjati-Gilani1, Daniel C. Alexander1

1Centre for Medical Image Computing, University College London, London, UK

We present a new model for fanning and bending white matter structures on a sub-voxel scale, and explore the suitability of the model for estimating the degree of fanning in each voxel of a human brain diffusion MRI acquisition. Preliminary work suggests that we can use the model to reconstruct fanning structures in real brain data and provide quantitative information about the fanning structure. Defining the structure more accurately allows more appropriate action to be taken by tractography algorithms, resulting in fewer false positive and false negative tracts.

                  1403.     Rapid Data Acquisition and Post-Processing for Diffusional Kurtosis Imaging

Jens Hesselberg Jensen1, Caixia Hu1, Joseph A. Helpern1,2

1Radiology, New York University School of Medicine, New York, NY, USA; 2Center for Advanced Brain Imaging, Nathan Kline Institute, Orangeburg, NY, USA

By utilizing an optimized data acquisition scheme together with a more efficient analysis algorithm, it is shown how to substantially reduce, compared to established approaches, the imaging and post-processing times for diffusional kurtosis imaging (DKI), a recent extension of diffusion tensor imaging which allows measures of diffusional non-Gaussianity to be estimated. This improved procedure permits full brain coverage to be obtained within a few minutes, thus facilitating the incorporation of DKI into clinical protocols. The rapid analysis algorithm should also make possible real-time DKI post-processing.

DTI Methods
Exhibit Hall 2-3                    Thursday 13:30-15:30

                  1404.     Outlier Detection for Diffusion Tensor Imaging by Testing for ADC Consistency

Hangyi Jiang1,2, Min-chung Chou1,2, Peter C.M. van Zijl1,2, Susumu Mori1,2

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

Diffusion tensor imaging (DTI) is an important tool to study brain white matter anatomy and its abnormalities. However, DTI-derived variables are affected by various sources of signal uncertainty. In this work, a new method to automatically detect and remove corrupted diffusion-weighted images due to subject motion is proposed. This approach iteratively identifies potential outliers by evaluating error-maps created from the apparent diffusion constant (ADC) maps derived from the original diffusion-weighted images and the estimated tensor matrix. Error clustering and gradient-neighboring analyses were used as criteria for outlier judgment.

                  1405.     Estimation of the Eddy-Current Induced Magnetic Field from Affine-Transformation Parameters and Its Relevance for the Comparability of DTI Data

Siawoosh Mohammadi1, Harld Möller2, Harald Kugel3, Dirk Müller2, Michael Deppe1

1Department of Neurology, University of Muenster, Münster, NRW, Germany; 2Magnetic Resonance Unit, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Sachsen, Germany; 3Department of Clinical Radiology, University of Muenster, Münster, NRM, Germany

The eddy current distortions and motion artifacts vary strongly between DTI data depending on the type of MR scanner and on the MR parameters. Although parts of these artifacts can retrospectively be corrected, residual EC artifacts remain and reduce the comparability of DTI data. In this study we present a method to estimate the EC induced magnetic field (EC field) from affine transformation parameters that were used for EC and motion correction. We further reconstructed parts of the long-term time course of EC field and demonstrated that this can be used to assess the comparability of DTI data.

                  1406.     Comparison of SNR and Diffusion Parameters on 1.5, 3.0 and 7.0 Tesla

Daniel Polders1, Hans Hoogduin1, Manus Joseph Donahue2, Jeroen Hendrikse1, Peter Luijten1

1Radiology, UMC Utrecht, Utrecht, Netherlands; 2Clinical neurology, University of Oxford, Oxford, UK

We compare the performance of a regular DTI sequence on three clinically relevant field strengths: 1.5, 3.0 and 7.0 Tesla. We inspected regional differences in the corpus callosum, corticospinal tract and optic radiations, comparing SNR and FA. Despite the fact that scanning at 7T is still far from optimal, a significant gain of SNR with field strength is shown. Even without further improvements on B0 and B1 shimming, we show that DTI at 7T is not only feasible but also beneficial for SNR.

                  1407.     Less Severe Spinal Cord Injury in Dysmyelinated Mice Evaluated Using DTI and Locomotion

Tsang-Wei Tu1, Joong Hee Kim2, Sheng-Kwei Song2

1Mechanical, Aerospace and Structrual Engineering, Washington University, St. Louis, MO, USA; 2Radiology, Washington University, St. Louis, MO, USA

In addition to the direct mechanical damage after spinal cord injury (SCI), secondary injury plays a crucial role in the progressive degeneration of the spinal cord. The lack of myelin sheaths in shiverer mice may provide a more hospitable environment for axonal regeneration after SCI. The long-term functional outcome is affected by both the initial damage and the extent of secondary injury. The less severely effected DTI parameters and hindlimb locomotion in shiverer mice suggest that the lack of myelin debris may indeed have significantly inhibition to the axonal regeneration in SCI. Our data suggest that the different degrees of recovery are probably due to the lack of myelin debris in the shiverer mice.

                  1408.     Fitting to Magnitude Diffusion MRI Data Using a Least Squares Algorithm Gives Biased ADC Values and Is Less Able to Characterise Necrosis

Simon Walker-Samuel1, Matthew Orton1, Lesley D. McPhail1, Simon P. Robinson1

1Cancer Research UK Clinical Magnetic Resonance Research Group, Institute of Cancer Research, Sutton, Surrey, UK

The noise in magnitude MR data is Rice-distributed, and it has been shown previously that fitting using a least-squares algorithm leads to biased ADC estimates. In this study, the magnitude of this bias in orthotopic PC3 tumours is investigated and compared with a robust maximum likelihood approach. It is found that least-squares over-estimates ADC by an average of 23.4 ± 12 %.. More significantly, regions of histologically-confirmed necrosis are not identifiable in ADC maps from the least-squares algorithm, but can be clearly observed in maximum-likelihood maps.

                  1409.     On the Battle Between Rician Noise and Phase-Interferences in DWI

Stefan Skare1, Samantha Holdsworth1, Rexford D. Newbould2, Roland Bammer1

1Radiology, Stanford University, Palo Alto, CA, USA; 2GlaxoSmithKline, London, UK

It has been shown that complex averaging benefits diffusion-weighted imaging (DWI) by reducing the influence of the noise bias in the ADC and DTI. However each component DW image must be phase corrected prior to averaging across diffusion repetitions and directions. The triangular windowing phase correction approach will help to remove phase-related artifacts due to pulsatile brain motion, but a large window radius still result in pronounced Rician noise in the mean DWI data. Here we have reduced the triangular window radius to minimize the amount of Rician noise in the final isotropic-DWI data, without introducing phase cancellations.

                  1410.     Automated Image Quality Assessment for Diffusion Tensor Data

James Meakin1, Serena Counsell2, Emer Hughes3, Jo V. Hajnal3, David J. Larkman3

1Physics Department, Imperial College London, London, UK; 2Imaging Sciences Department, Clinical Sciences Centre MRC, London, UK; 3Imaging Sciences Department, Imperial College London, London, UK

In single shot EPI based DTI motion between acquisitions can be corrected by image registration approaches but individually damaged images are generally uncorrectable. This work outlines an algorithm designed to automatically identify and reject damaged images in large diffusion datasets, an otherwise manually intensive step. The approach calculates an estimate of the diffusion images using a data driven forward model and then compares this prediction to the acquired data using 2D image correlation to identify outlier images. The method has been tested on 9 preterm infant data sets and 9 adult data sets.

                  1411.     Exploring the White Matter Microstructure Underpinning Electrophysiological Dynamics: A Combined DT-MRI and MEG Study

Derek K . Jones1, Alex Leemans1, Christopher John Evans1, Krish D. Singh1, Suresh D. Muthukumaraswamy1

1CUBRIC, School of Psychology, Cardiff University, Cardiff, Wales, UK

Neuronal oscillations at specific frequencies appear to be fundamental to the implementation of perception and cognition within the brain. Gamma oscillations (30-100 Hz) have been proposed as a temporal coding scheme through which distributed neuronal groups are able to synchronise – allowing communication between these areas and underlying the “binding” of stimulus features. We combined DT-MRI and MEG data on gamma oscillations to address the question of whether whether there is a role for white matter pathways in gamma oscillatory behaviour. Certain aspects of our finds are expected, while others are not – leading to important insights about analysis of DT-MRI data.

                  1412.     Quantitative Mapping of Diffusion Characteristics Under the Cortical Surface

Bang-Bon Koo1, Vibhu Sachdev1, Jong Min Lee2, Dae-Shik Kim1

1Biomedical imaging center, Boston University, Boston, MA, USA; 2Biomedical Engineering, Hanyang University, Seoul, Korea

We introduced a new method that allows robust localized analysis of WM diffusivity in peripheral cortex and showed that DTI mapping of peripheral WM structure reveals regional characteristics. While we applied this framework on young normal population, we need to confirm whether peripheral diffusion successfully reveal spatio-temporal age related maturation process. Moreover, combining functional imaging techniques will allow to investigate structure-functional relationships.

                  1413.     Simulated DTI Data Sets for the Evaluation of Voxel Based Analysis Methods

Wim Van Hecke1,2, Alexander Leemans3, Steve De Backer1, Paul M. Parizel2, Jan Sijbers1

1University Antwerp, Antwerp, Belgium; 2Radiology, Antwerp University Hospital, Antwerp, Belgium; 3CUBRIC, University of Cardiff, Cardiff, Wales, UK

In this work, simulated DTI data sets with a predefined pathology (i.e. known spatial location, size, and shape of the altered diffusion properties) are constructed. The simulated DTI data sets can be used to investigate the reliability, accuracy, and precision of a voxel based or region of interest analysis. In addition, the effect of the different parameters and post processing steps that are involved in the pipeline of a voxel based analysis can be examined and even optimized, which could lead to a more reliable, standardized, and consistent post-processing of DT images for studying different pathologies.

                  1414.     Polyvinylpyrrolidone (PVP) Water Solutions as Isotropic Phantoms for Diffusion MRI Studies

Carlo Pierpaoli1, Joelle Sarlls1, Uri Nevo1,2, Peter J. Basser1, Ferenc Horkay1

1NIH, Bethesda, MD, USA; 2Department of Biomedical Engineering, Tel-Aviv University, Tel-Aviv, Israel

In this work we characterize the diffusion behavior of aqueous solutions of PVP as candidates for a non-toxic diffusion MR phantom suitable for use in a clinical setting. We find that PVP solutions have desirable characteristics. They have temporal stability, show gaussian diffusion profiles, and cover the large range of diffusivities observed in human tissues.

                  1415.     Effects of Preprocessing on Goodness of Fit Measures in Premature Neonatal DTI

Drew Morris1, Revital Nossin-Manor1, Margot J. Taylor1, John G. Sled2,3

1Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada; 2Physiology Experimental Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; 3Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada

DTI was performed on 19 premature neonates (mean post conceptional age 29 weeks). Motion/eddy current correction, B0 field inhomogeneity correction and outlier rejection were applied to the data prior to a nonlinear tensor fit. Goodness of fit in the model was evaluated by measuring the mean sum squared residual before and after each processing step. Each step was found to reduce model residuals, thereby improving the model. Fractional anisotropy was also found to decrease with preprocessing. It was also demonstrated that removing outliers before other preprocessing steps showed better data improvement than doing so afterwards in voxels with higher anisotropy.

                  1416.     Longitudinal Changes in Diffusivity After Long-Term Storage of Postmortem Tissue

Tim B. Dyrby1, William FC. Baaré1, Daniel C. Alexander2, Jacob Jelsing3, Ellen Garde1, Lise V. Søgaard1

1Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital, Hvidovre, Denmark; 2Centre for Medical Image Computing, Dept. Computer Science, University College London, London, UK; 3Research Laboratory for Stereology and Neuroscience, Copenhagen University Hospital, Bispebjerg, Denmark

Compared to in vivo, diffusion weighted imaging (DWI) obtained postmortem benefits from longer scanning times, thereby improving both image resolution and SNR. An additional, overseen feature is the possibility of long-term storage, which would allow the instigation of brain repositories from where specimens could be loaned for use in DWI projects. In this study, we have investigated possible longitudinal changes in diffusivity of archived postmortem brain tissue over a nearly four-year period. Repeated DWI measurements were obtained on perfusion-fixated pig brains, with steps taken to ensure that the postmortem DWI was representative of in vivo conditions.

                  1417.     DTI Smoothing by Hierarchical, Adaptive and Robust Strategy

Songyuan Tang1, Yong Fan1, Hongtu Zhu2, Wei Gao1, Weili Lin1, Dinggang Shen1

1Department of Radiology and BRIC,University of North Carolina, Chapel Hill, NC, USA; 2Biostatistics and Biomedical Research Imaging Center, University of North Carolina, Chapel Hill, NC, USA

We have proposed a new method for adaptively estimating and smoothing DTs based on DWIs. The proposed method has three distinct novelties. First, it used robust anisotropic diffusion in log-Euclidean space for DT smoothing. Second, it employed a hierarchical strategy to adaptively smooth DTs. Finally, to achieve adaptive tensor estimation, an iterative estimation of weighting coefficients was employed to characterize the similarity between neighboring tensors. Both the results on simulated and human data suggest that the proposed approach outperforms the currently existing approach. Evaluation of the performance of the proposed method on large dataset is currently ongoing.

                  1418.     Analysis of High b-Value Diffusion Images Using a Fractional Order Diffusion Model with Denoising Image Reconstruction

Qing Gao1,2, Justin P. Haldar3, Novena Rangwala1,2, Richard L. Magin2, Zhi-Pei Liang3, Xiaohong Joe Zhou1,4

1Center for Magnetic Resonance Research, University of Illinois Medical Center, Chicago, IL, USA; 2Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA; 3Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA; 4Departments of Radiology, Neurosurgery, and Bioengineering, University of Illinois Medical Center, Chicago, IL, USA

Low signal-to-noise ratio (SNR) has been a major source of error in quantitative analyses of diffusion images with high b-values. In this study, we have applied a statistical model for joint reconstruction and denoising on a set of images acquired from the human brain with b-values up to 3,300 s/mm2. The denoised images were analyzed using a fractional order (FO) diffusion model to obtain a set of diffusion parameters. With a more than two-fold increase in SNR and a negligible compromise of spatial resolution, the accuracy of the diffusion parameters has been considerably improved, making it possible to apply complex diffusion analysis with high b-values to patient studies.

                  1419.     Exploring Analytic Models of the Diffusion MR Signal in Fixed Rat Brain Tissue

Eleftheria Panagiotaki1, Hubert M. J. Fonteijn1, Shahrum Nedjati-Gilani1, Matt G. Hall1, Daniel C. Alexander1

1Centre for Medical Image Computing, Computer Science, University College London, London, UK

In this work we devise a protocol to allow examination of parallel and perpendicular signals in rat brain white matter and use this protocol to compare three models of diffusion. The models are the diffusion tensor (DT), Behrens’ model (ball and stick) and Alexander’s simplified version of CHARMED (cylinder model). We find that the cylinder model explains the perpendicular signal well; however the common assumption of free diffusion in the parallel direction to the fibres is not supported by the models we fit to our scan data.

                  1420.     Diffusion Weighted Imaging of the Human Brain in P. Falciparum Malaria

Christina Louise Tosti1, Jordan Muraskin1, Xavier Golay2, Jiraporn Laothamatas3, Marc Van Cauteren4, Melvyn B. Ooi1, Varinee Lekprasert3, Noppadon Tangpukdee3, Srivicha Krudsood3, Wattana Leowattana3, Sornchai Looareesuwan3, Polrat Wilairatana3, Robert L. DeLaPaz1, Gary M. Brittenham1, Adam M. Brickman1, Truman R. Brown1

1Columbia University, New York, NY, USA; 2University College London, London, UK; 3Mahidol University, Bangkok, Thailand; 4Philips Healthcare Systems Asia Pacific, Tokyo, Japan

A better understanding of the pathogenesis of malaria is needed to reduce fatalities and combat emerging drug resistance. P. falciparum  malaria remains entirely within the vascular space of the brain, and the means whereby it can cause severe neurological dysfunction, coma and death are unknown. To assess the sensitivity of MR to cerebral changes in malaria and, in particular, changes in the apparent diffusion coefficient, we performed serial MRI studies at 3T in adult patients admitted for malarial treatment in Bangkok, Thailand and compared the results to controls using a voxelwise analysis.

                  1421.     Quantitative Measures of Glioma Edge Characteristics on Diffusion Weighted Images – Interobserver Agreement.

John Robert Cain1, Gerard Thompson1, Samantha Jane Mills1, Alan Jackson1

1Imaging Science and Biomedical Engineering, University of Manchester, Manchester, UK

A reproducibility study of two quantitative measures of apparent diffusion coefficient (ADC) image tumour boundaries. ADC Transition Coefficient into Oedema (ATCO) is a measure of change of ADC signal across the interface between oedema and white matter, ADC Transition Coefficient into Tumour (ATCT) is a measure of change of ADC signal across the oedema/solid tumour interface. Twenty-three patients with glioma were imaged on a 3T system, ADC images were analysed by two radiologists using a clearly defined method. These measures are simple, quick to perform and have excellent reproducibility, interclass correlation coefficient 0.895 and 0.834 for ATCO and ATCT respectively.

                  1422.     Use of Fractional Anisotropy for Determination of the Cut-Off Value in 11C-Methionine Positron Emission Tomography for Glioma.

Manabu Kinoshita1, Naoya Hashimoto1, Tetsu Goto1, Takufumi Yanagisawa1, Naoki Kagawa1, Haruhiko Kishima1, Jun Hatazawa2, Toshiki Yoshimine1

1Neurosurgery, Osaka University Graduate School of Medicine, Suita, Osaka, Japan; 2Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan

Assessment of biological features of malignant brain tumor by means of non-invasive image modality is required in the field of neurosurgery. Previous studies have challenged this issue by looking into individual data obtained from multimodal neuroradiological assessments. In this research, we have attempted to integrate DTI-MRI and 11C-methionine PET data to compensate each other to determine the cut-off values for discriminating normal and abnormal tissues. We believe that our findings will benefit the understanding and interpretation of malignant brain tumor imaging on DTI and 11C-methionine PET.

                  1423.     Patching Cardiac and Head Motion Artefacts in Diffusion Imaging

Marcel Peter Zwiers1

1Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, -, Netherlands

Motion artefacts are an important but often ignored problem in diffusion weighted imaging, and can easily corrupt diffusion model estimations. The post-processing method proposed in this paper uses robust tensor estimation techniques and specifically takes the spatio-temporal structure of the most common artefacts, namely from head and cardiac motion, into account. Simulations demonstrate that the method is more robust and accurate than previous methods and, moreover, improves results significantly using real DWI data. The resulting weights are not limited to diffusion tensor imaging but can also be used to estimate higher order models.

                  1424.     Measurement of Apparent Long-Range Diffusion of 3He Using Pulsed Gradient Spin Echo T2 in the Rat Lung at Low Magnetic Field Strength

Giles Santyr1,2, Ryan Kraayvanger1,2, Xiaojun Xu1,2, William Dominguez-Viqueira1,2

1University of Western Ontario, London, Ontario, Canada; 2Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada

The Apparent Diffusion Coefficient (ADC) of hyperpolarized 3He in the lung has recently been shown to have heightened sensitivity to lung diseases, such as COPD, when measured in the long range diffusion regime (i.e. ~seconds). However, the susceptibility induced gradients within the lung limit the time-scale and pulse sequences possible for measuring the ADC on typical clinical MR systems (1.5 – 3.0 T). We explore the use of a Pulsed Gradient Spin Echo technique at low magnetic field strength (1-100 mT), where susceptibility induced gradients are greatly reduced, to measure ADC of hyperpolarized 3He.

                  1425.     Intravoxal V1-IP: An Improved White Matter Index Compared to Diffusion Anisotropy

Shu-Wei Sun1,2

1Biomedical Engineering, Loma Linda University, Loma Linda, CA, USA; 2Non-invasive Imaging Lab, Radiation Medicine, Loma Linda University, Loma Linda, CA, USA

Diffusion anisotropy has been widely used to identify white matter, but is sensitive to noise and the disease processes. The major eigenvector of diffusion tensor, V1, has been widely used to reconstruct neural tractography. We converted V1 to an objective DTI index, the intra-voxel V1-IP, to serve as an objective DTI index to differentiate white matter from gray matter and ventricles. Comparing the intra-voxel V1-IP and relative anisotropy (RA), we demonstrated that intra-voxel V1-IP is a better white matter index than RA as it is insensitive to noise and neuronal diseases.

                  1426.     Hierarchical Diffusion Tensor Image Registration Based on Tensor Regional Distributions

Pew Thian Yap1, Hongtu Zhu2, Weili Lin1, Dinggang Shen1

1Department of Radiology and BRIC, University of North Carolina, Chapel Hill, NC, USA; 2Department of Biostatistics and BRIC, University of North Carolina, Chapel Hill, NC, USA

We propose a novel DTI registration algorithm which leverages on the hierarchical guidance of tensor regional distributions and local boundaries, both extracted directly from the tensors. This is in contrast with conventional methods which typically compute regional and edge information based on tensor scalar maps, which might not necessarily reflect the actual tensor information. For each voxel, statistical measures such as mean and variance are computed in various neighborhood sizes, extracting multiscale information. Edge boundaries are obtained by an extended Canny edge detector which works directly on the tensors. Distinctive features are then selected hierarchically as landmark points to guide the registration.

                  1427.     Estimating White Matter Tract Volume in Partial Volume Voxels with Diffusion MRI

Jakub P. Piatkowski1, Amos J. Storkey1, Mark E. Bastin2

1School of Informatics, University of Edinburgh, Edinburgh, UK; 2Medical Physics, University of Edinburgh, Edinburgh, UK

Anisotropy in the water diffusion MRI (dMRI) signal can be used to determine local white matter (WM) direction and segment major pathways using tractography. It has also been linked, in the form of fractional anisotropy (FA), to WM coherence and therefore, indirectly, to WM integrity. It has been shown, however, that in partial volume (PV) voxels FA is underestimated compared with voxels containing only WM. This can lead to an inaccurate estimation of either tract volume or coherence. We address this problem by fitting a fully physically plausible, 2-compartment model to the dMRI data that correctly describes PV effects.

                  1428.     Between-Scanner Variation in Normal White Matter ADC in the Setting of a Multi-Center Clinical Trial

Jing Huo1, Matthew S. Brown1, Jeffry R. Alger1,2, Hyun J. Kim3, Whitney B. Pope3, Kazunori Okada4, Jonathan G. Goldin3

1Department of Radiological Sciences , UCLA, Los Angeles, CA, USA; 2Department of Neurology, UCLA, Los Angeles, CA, USA; 3Department of Radiological Sciences, UCLA, Los Angeles, CA, USA; 4Computer Science Department, San Francisco State University, San Francisco, CA, USA

The aim was to study the between-scanner variation and the scan-rescan variation of normal brain white matter apparent diffusion coefficient (ADC) measurements in the setting of multi-center chemotherapy clinical trial for glioblastoma multiforme which used different scanner models. Measured baseline BWM ADC values were consistent across six different scanner models from two manufacturers but ADC coeeficient of variation did vary between scanner models. The scanners showed no difference in their ability to reproduce BWM ADC measurement from the same patient on two successive visits.

                  1429.     Multiple Fiber Diffusion Anisotropy Analysis in Autistic Children

Zhenyu Zhou1,2, Weihong Guo3, Tianyu Tang2, Wei Liu1, Bradley S. Peterson1, Yijun Liu2, Dongrong Xu1

1MRI Unit, Psychiatry, Columbia University, New York, NY, USA; 2Psychiatry, University of Florida, Gainesville, FL, USA; 3Mathematics, University of Alabama, Tuscaloosa, AL, USA

A new Diffusion Anisotropy Index R4 is developed for characterizing the degree of fiber crossing in DTI data, using a measure of apparent diffusion coefficient and a method based on spherical harmonic series. We then used R4 to investigate the relationship between diffusion anisotropy and multiple fibers crossing within individual voxels. Group differences of FA and R4 were computed respectively based on DT-MRI data of six autistic children and six healthy controls. We found that in the autistic population, brain regions where fibers are highly crossing (corpus callosum/lateral ventricle and arched fiber/precentral gyrus) are featuring with high R4 and low FA values simultaneously, indicating possibly a different mechanism other than pathological abnormality in white matter that causes low FA.

                  1430.     Phenotyping Aging of the Spontaneously Hypertensive Rat Brain Using 3D Diffusion Tensor Imaging at 9.4T: A Preliminary Study

Ping Wang1, Suzanne Wehrli2, Elizabeth Stambrook1, Christos Davatzikos3, Ragini Verma3, Thomas Floyd1,4

1Anesthesiology & Critical Care, University of Pennsylvania, Philadelphia, PA, USA; 2NMR Core Facility, The Children's Hospital of Pennsylvania, Philadelphia, PA, USA; 3Radiology, University of Pennsylvania, Philadelphia, PA, USA; 4Neurology, University of Pennsylvania, Philadelphia, PA, USA

The Spontaneously Hypertensive Rat (SHR) is phenotypically characterized by hypertension by age 4 months, with cerebrovascular changes evidenced by age 6 months. The SHR is widely used in research for its similarities with humans suffering from hypertension related disease. MRI-based phenotyping of the SHR brain may offer further insight into stroke and cognitive impairment in this strain and its appropriateness for comparative investigations into human disease. The purpose of this work is to longitudinally assess the hypertension related changes in brain microarchitecture of this important disease model, the SHR, using 3D high resolution DTI at 9.4T.

                  1431.     Improving Diffusion Tensor Imaging Segmentation Through an Adaptive Distance Learning Scheme

Paulo Reis Rodrigues1, Anna Vilanova1, Thorsten Twellmann2, Bart M. ter Haar Romeny1

1Biomedical Image Analysis, Technical University of Eindhoven, Eindhoven, Noord Brabant, Netherlands; 2MeVis Medical Solutions AG, Bremen, Germany

Similarity of diffusion tensors is a crucial point in several applications like segmentation, group statistical analysis, etc. The selection of the most suitable measure, for a given task, is not always clear and often done by trial and error. We present a proof of concept of an initially flexible learning scheme that infers the measure or combination of measures that achieves the best discrimination between a user selected Region of Interest and a representative set of tensors of the whole volume. The results demonstrate the method’s potential to infer the ideal parameters for a task specific segmentation algorithm, region growing.

                  1432.     Diffusion Tensor Shape and Tertiary Eigenvector Encoded Colormaps Reveal Features in Human Brain Tumor

L-H. Dennis Cheong1, C-C. Tchoyoson Lim1,2

1Neuroradiology, National Neuroscience Institute, Singapore, Singapore; 2Diagnostic Radiology, Yong Loo Lin School of Medicine National University of Singapore, Singapore

DTI has mainly been used to assess brain white matter fibers, but the potential to assess micro-structures at the tumor cell level is unexplored. DTI contains much information beyond FA and v1FA colormap that has not been well exploited to study tumor microstructure. We found the tensor shapes encoded colormaps can potentially allow the identification of a rim of planar tensors at the boundary of a tumor and extracted information contained within the tertiary eigenvector.

                  1433.     Evolution of Diffusion Tensor Parameters After Permanent Experimental Stroke in Rats

Miia Pitkonen1,2, Usama Abo-Ramadan1,2, Eric Pedrono1,2, Ivan Marinkovic1,2, Daniel Strbian1,2, Aysan Durukan1,2, Turgut Tatlisumak1,2

1Department of Neurology, Helsinki University Central Hospital, Helsinki, Finland; 2Experimental MRI Laboratory, Biomedicum Helsinki, Helsinki, Finland

In the present work, the temporal evolutions of the diffusion tensor imaging (DTI) parameters (fractional anisotropy (FA) and rotationally invariant apparent diffusion coefficient (ADC)) were measured after permanent middle cerebral artery occlusion (MCAO). Wistar rats (n=9) were subjected to focal cerebral ischemia. They were imaged at 2 and 3.5 hours, 1, 2, 3, and 4 days, 1, 2, 4, 6, and 8 weeks. The MRI measurements were performed with a 4.7 T MR Scanner. This study showed that, after permanent MCAO, there are differences in the temporal evolution of FA in different brain tissues.

                  1434.     Diffusion Anisotropy Measure Based on the Basis of Tesseral Harmonics

Yuliya Kupriyanova1, Oleg Posnansky1, N. Jon Shah1,2

1Institute of Neurosciences and Biophysics, Research Centre Juelich, Juelich, Germany; 2Faculty of Medicine, Department of Neurology, RWTH Aachen University,  JARA, Aachen, Germany

We present a method for the characterization of diffusion anisotropy based on the analysis of the apparent diffusion coefficient profile in terms of the tesseral harmonics series coefficients with a resulting brain anisotropy map. The tesseral harmonics are an alternative set of spherical harmonics for real-valued functions. To infer the underlying diffusion process, we applied the rotationally-invariant anisotropy index. The characterization of the diffusion anisotropy based on our method is computationally simple, fast and is consistent with the known fibre anatomy.

                  1435.     Effect of B-Value and TE on the Estimation of Intramyocellular Diffusion Properties in the Presence of Edema

Bruce M. Damon1

1Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, USA

Diffusion tensor imaging (DTI) may be able to provide information about intramyocellular muscle damage distinctly from T2, but its ability to do so may be confounded by the presence of edema in SNR, TE, and b-value dependent manners. Using simulations, it was found that varying TE does not affect the estimation of intramyocellular water diffusion properties, but that SNR, b-value, and the volume fraction of the extracellular space do. Using conventional DTI acquisition schemes, the effects of edema cannot be well controlled, and so they must be accounted for when interpreting muscle DTI data in the presence of edema.

Diffusion:  Fiber Tracking
Exhibit Hall 2-3                    Monday 14:00-16:00

                  1436.     Stochastic Fibre Tracking: An Average Curves Approach

Nagulan Ratnarajah1, Andy Simmons2, Ali Hojjat3

1Department of BioSciences, University of Kent, Canterbury, Kent, UK; 2Centre for Neuroimaging Sciences, Kings College London, UK; 3Department of BioSciences, University of Kent, UK

To resolve orientational uncertainties in diffusion tensor imaging, probabilistic fiber tracking has received considerable interest. Current approaches model the uncertainty at each voxel with a probability density function (PDF) for the fiber orientations, then propagate a streamline in randomly sampled directions, and the most probable path is estimated using the connectivity map. We consider the random path as a set of curves, and find the most probable path estimated directly from the generated curves using average curves. A simple stochastic model is presented here and two implementations evaluated using phantom and in vivo diffusion MRI data

                  1437.     Diffusion Simulation Tractography for High Angular Resolution Diffusion Imaging

Ning Kang1, Gregory T. Balls1, Lawrence R. Frank1,2

1Center for Scientific Computation in Imaging, University of California San Diego, La Jolla, CA, USA; 2Radiology Department, VASDHS, San Diego, CA, USA

Regions of complex fiber architecture in the presence of multiple fiber orientations within a single voxel are common in the brain and pose a significant problem for standard DTI (Diffusion Tensor Imaging) based fiber tracking methods, therefore limit the utility of HARDI (High Angular Resolution Diffusion Imaging) acquisition techniques. Here we propose an extension of our previously demonstrated diffusion simulation tractography method to HARDI technique that has potentials to overcome these limitations and thus provide more information about connectivity in the brain.

                  1438.     Probabilistic Fiber Tracking Using the Residual Bootstrap with Constrained Spherical Deconvolution MRI

Ben Jeurissen1, Alexander Leemans2, Jacques-Donald Tournier3,4, Jan Sijbers1

1Visionlab, Dept. of Physics, University of Antwerp, Antwerp, Belgium; 2CUBRIC, School of Psychology, Cardiff University, Cardiff, Wales, UK; 3Brain Research Institute, Florey Neuroscience Institutes (Austin), Melbourne, Victoria, Australia; 4Dept. of Medicine, University of Melbourne, Melbourne, Victoria, Australia

We present a new probabilistic tractography algorithm based on constrained spherical deconvolution (CSD) of diffusion weighted (DW) MRI and the residual bootstrap. Using simulations we show that the residual bootstrap is an accurate method to characterize CSD fiber trajectory uncertainty. As opposed to classic bootstrapping, the residual bootstrap only requires a single DW acquisition, making it clinically feasible. We compare our algorithm to state-of-the-art probabilistic diffusion tensor imaging (DTI) tractography, using both simulated and real DW data. Our algorithm is shown to be much less prone to fiber dispersion than probabilistic DTI tractography in regions of multiple fiber orientations.

                  1439.     Free-Spin Tracking: A Novel Global Tractography Algorithm

Pierre Fillard1, Cyril Poupon1, Jean-François Mangin1

1LNAO, CEA/DSV/I2BM/Neurospin, Gif/Yvette, France

We propose a novel tractography algorithm able to handle various fiber configurations like crossings. Fibers are modeled as chains of unit elements called spins. Spins are allowed to move, merge with other spins, and duplicate to form longer pieces of fibers. The entire white matter is tracked at once, which allows pieces of fibers coming from the entire volume to help find the optimal neuronal pathway in crossing regions. Experiments on two realistic MR phantoms show that such approach is successful in reconstructing fiber crossings and kissings, even using a simple diffusion model like the tensor.

                  1440.     Model-Based Streamline Rejection for Probabilistic Tractography

Jonathan D. Clayden1, Chris A. Clark1

1Institute of Child Health, University College London, London, England, UK

This work describes a method for rejecting false positive pathways in probabilistic tractography based on a model of tract shape. Unlike with region-of-interest methods, the rejection criterion is probabilistic and based on the topology of the tract in each individual. In contrast to thresholding approaches, the method is sensitive to the meaning of the data and has no user-defined parameters. The common observation of declining visitation count with distance from a seed point is also alleviated.

                  1441.     Preliminary Results on the Use of STAPLE for Evaluating DT-MRI Tractography in the Absence of Ground Truth

Sonia Pujol1, Carl-Fredrik Westin2, Ross Whitaker3, Guido Gerig3, Tom Fletcher3, Vincent Magnotta4, Sylvain Bouix5, Ron Kikinis1, William M. Wells III1, Randy Gollub6

1Surgical Planning Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; 2Laboratory of Mathematics in Imaging, Brigham and Women's Hospital, Harvard Medical School, Boston, MA; 3Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT; 4University of Iowa, Iowa City, IA; 5Psychiatry Neuroimaging Laboratory, Boston, MA; 6Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA

We describe preliminary results obtained from a framework for evaluating DT-MRI tractography algorithms that uses STAPLE (Simultaneous Truth and Performance Level Estimation) to estimate the performance of the methods in the absence of ground truth. In tests on a mathematical phantom we show that STAPLE is able to characterize fiber tracking performance by comparing its findings to true performance findings. We apply the framework to four methods operating on four white matter fasciuli in real data, and describe the results of this new approach for validating tractography.

                  1442.     Whole-Brain Track-Density Mapping as a Tool for Fiber Tractography

Fernando Calamante1,2, Jacques-Donald Tournier1,2, Heath Pardoe1,2, Alan Connelly1,2

1Brain Research Institute, Florey Neuroscience Institutes (Austin), Melbourne, Victoria, Australia; 2Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia

This study describes the use of whole-brain track-density mapping as a complementary tool for tractography. In particular, it is demonstrated to aid in definition of seed and target regions for tractography (making that important step more robust), and to facilitate normalization of fiber tracks for inter-subject comparisons. The maps are shown to have very good anatomical contrast, high spatial resolution, high SNR and, importantly, they are exactly in the same space (including distortions) as the diffusion data. Whole-brain track-density maps should play an important role in clinical and research studies.

                  1443.     A Global Approach to Diffusion Tensor Neighborhood Tractography

Paul A. Armitage1, Susana Munoz Maniega1, Mark E. Bastin2

1Clinical Neurosciences, University of Edinburgh, Edinburgh, City of Edinburgh, UK; 2Medical & Radiological Sciences (Medical Physics), University of Edinburgh, Edinburgh, City of Edinburgh, UK

Neighborhood tractography has been shown to be beneficial for automating the extraction of white matter pathways in the brain. However, present implementations are generally specific to local tractography algorithms, such as those based on streamlining. Therefore, a neighborhood tractography framework is developed suitable for use with global tractography algorithms. When applied in conjunction with fast marching tractography, the method improved the automatic extraction of connectivity maps for white matter pathways of interest when compared to transposing seed points by registration alone.

                  1444.     Spatial Random Effects Modelling of Crossing Fibre Voxels in Diffusion MRI

Martin David King1, Chris Alan Clark1, David Gadian1

1UCL Institute of Child Health, University College London, London, UK

A spatial random effects model has been used in the analysis of multiple-directions diffusion-weighted MR data, focussing on the crossing-fibre problem that arises in tractography. The analysis was performed with the Markov chain Monte Carlo Gibbs sampler algorithm, using crossing fibre low b-value (1000 s mm-1) 20 directions diffusion data acquired from the pons. The results show that spatial random effects modelling, based on a conditional autoregressive prior, provides well resolved components compared with those obtained with an equivalent independent voxel-by-voxel treatment. We conclude that the spatial random effects modelling approach provides a useful extension to current tractography methods.

                  1445.     HYFF-HYbrid Tractography with Fiber Assignment by Continuous Tracking and Fast Marching

Hao Huang1,2, Xin Fan1

1Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, USA; 2Department of Radiology, UT Southwestern Medical Center, Dallas, TX, USA

Tractography based on diffusion tensor imaging (DTI) provides an efficient and noninvasive means to reveal the morphology of white matter tracts. Conventional streamline method such as FACT is known to have limitation of tracing only single lines. Fast marching tractography (FMT) allows fiber crossing and branching based on DTI, but is bound to discretization errors. The proposed HYFF (HYbrid tractography with Fiber assignment by continuous tracking and Fast marching) is a streamline method which ensures correct directions of tracing by forcing the traced lines to go downstream of the time field generated from FMT.

                  1446.     Measuring Error of Diffusion MRI-Based Brain Connectivity Matrices with Residual Bootstrap

Christopher T. Nguyen1,2, Roland G. Henry2,3, SungWon Chung2,3

1Bioengineering, University of California Berkeley, Berkeley, CA, USA; 2Center for Molecular and Functional Imaging, Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA; 3Graduate Group in Bioengineering, University of California San Francisco and Berkeley, San Francisco, CA, USA

Recently, noninvasive techniques using diffusion MRI were used to construct in-vivo brain connectivity matrices and networks. While exciting, the potential variability of these connectivity matrices is not known and will depend on several factors including data acquisition and fiber tracking algorithms. Using residual bootstrap, we propose a method to measure the errors in whole brain connectivity matrices and present results based on a deterministic fiber-tracking algorithm. The resulting matrix demonstrated high variability in many of the pairs of ROIs especially in known crossing fiber regions.

                  1447.     Improved Probabilistic Tractography Using Atlas-Based Fiber Tracking

Qing Xu1, Adam W. Anderson1, John C. Gore1, Zhaohua Ding1

1Vanderbilt University Institute of Imaging Science (VUIIS), Vanderbilt University, Nashville, TN, USA

A probabilistic fiber tracking algorithm generates a set of fibers that reflect the distribution of underlying neuronal pathways by processing the diffusion tensor images. As imaging artifacts such as random noise and partial volume averaging usually render reconstructed fibers unreliable, typically certain prior knowledge is used to regularize the fiber tracking process. In this contribution, we propose a novel atlas based probabilistic fiber tracking algorithm that incorporates prior knowledge from a white matter fiber atlas, thereby eliminating the need for the commonly used heuristic priors.Preliminary experiments demonstrate that the atlas-guided method improves probabilistic tractography over methods with heuristic priors.

                  1448.     Automated Registration, Segmentation and Labeling of White Matter Fiber Tracts

Qing Xu1, Adam W. Anderson1, John C. Gore1, Zhaohua Ding1

1Vanderbilt University Institute of Imaging Science (VUIIS), Vanderbilt University, Nashville, TN, USA

Brain white Matter (WM) fibers are widely reconstructed by using magnetic resonance diffusion tensor imaging (DTI). A fiber-to-bundle registration algorithm is proposed to coregister a whole-brain target fiber set with an already reconstructed reference bundle set. Using the resulting transformation, the fibers from different target datasets can all be warped into the reference space for comparison and group analysis. Moreover, their bundle type can be automatically labeled. Experiments with eight human brain DTIs have shown significant similarity of the reference with the post-registered target bundles, and also high consistency of the resulting bundles with a manually segmented ground truth.

Methods & Applications in Healthy Subjects
Exhibit Hall 2-3                    Tuesday 13:30-15:30

                  1449.     Gender Differences in White Matter Microstructure in the Adult Brain Revealed by Tract Based Spatial Statistics.

Emer Judith Hughes1, David J. Sharp2, Derek L.G Hill3, Alle Meije Wink4, Joseph V. Hajnal4, Serena J. Counsell5

1Robert Steiner MRI Unit, Hammersmith Hospital, Imperial College, London, England, UK; 2Cognitive Neuroimaging Group, MRC Clinical sciences Centre, Imperial college, London, England, UK; 3The London Bioscience Innovation Centre, IXICO ltd, London, England; 4Hammersmith Hospital, Imperial College, Robert Steiner MRI Unit, London, England, UK; 5Robert Steiner MRI Unit, Hammersmith Hospital, Imperial college, London, England, UK

Diffusion tensor imaging studies (DTI) have found evidence for sexual dimorphism in a number of white matter tracts, with males having higher fractional anisotropy (FA) than females. The aim of this study was to assess whole brain white matter, in a large study group, in order to assess the extent of these microstructural differences using Tract Based Spatial Statistics (TBSS). Our results demonstrated extensive regions in the brain where the white matter microstructure differs between males and females, including a number of regions that have not been previously reported.

                  1450.     Separate Assessment of Diffusion Properties of NAA and NAAG at 7T

Hermien E. Kan1, Matthias J. P. van Osch1, Maarten J. Versluis1, Aranee Techawiboonwong2, Mark A. van Buchem1, Andrew J. Webb1, Itamar Ronen2

1Leiden University Medical Center, Leiden, Netherlands; 2Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA, USA

In diffusion weighted spectroscopy (DWS), the behaviour of intra cellular metabolites can potentially give information on compartmentation, in contrast to water for which measurements are not specific for any compartment. In this work, we measure for the first time in humans the different diffusive properties of N-Acetyl aspartate (NAA) and N-Acetylaspartylglutamate (NAAG) by applying DWS at a field strength of 7T, where there is sufficient spectral separation to perform this measurement

                  1451.     Separation of Fiber Tracts Within the Human Cingulum Bundle Using Single-Shot STEAM DTI with Partial Fourier Encoding and Parallel Imaging

Alexander Karaus1, Sabine Hofer1, Jens Frahm1

1Biomedizinische NMR Forschungs GmbH, Goettingen, Germany

The purpose of this work was to present the cinglulum bundle located above the corpus callosum. It consists of a complex white matter fiber tract of the human brain that comprises long association fibers, commissural fibers, and various U-fibers. The fiber tractography was achieved by diffusion tensor imaging using a single-shot STEAM-sequence with 24 gradient directions at 1.8 mm isotropic resolution. In order to map the full cingulum bundle 41 oblique sections in AC-PC orientation were acquired without gaps in an interleaved order.

                  1452.     How to Smooth Diffusion Tensor Images in a Voxel Based Analysis?

Wim Van Hecke1, Alexander Leemans2, Steve De Backer1, Paul M. Parizel3, Jan Sijbers1

1University Antwerp, Antwerp, Belgium; 2CUBRIC, University of Cardiff, Cardiff, Wales, UK; 3Radiology, Antwerp University Hospital, Antwerp, Belgium

Many DTI studies are starting to use voxel based analysis (VBA) to evaluate differences in the diffusion properties between healthy diseased subjects. In this work, simulated DTI data sets with a predefined pathology are used to evaluate the sensitivity and specificity of the pathology detection comparing isotropic and anisotropic smoothing kernels with different full width at half maximum. We demonstrate that the use of anisotropic kernels can increase the sensitivity and the specificity of detecting a pathology in a VBA. We therefore suggest to apply an anisotropic smoothing method in DTI group studies to increase SNR while preserving WM boundaries.

                  1453.     Diffusion Tensor Invariants and Principal Eigenvector Coherence Changes with Field Strength at Various b-Value Ranges

Ai Wern Chung1, Martin D. King1, David L. Thomas2, Roger J. Ordidge2, Chris A. Clark1

1Radiology & Physics Unit, UCL, Institute of Child Health, London, UK; 2Department of Medical Physics, UCL, Wellcome Trust High Field MR Research Laboratory, London, UK

Our aim is to assess the effect of magnetic field strength on diffusion tensor invariants, including principal eigenvector coherence, over b-values 0 to 3000 s mm-2 in healthy subjects. We found a significant increase in FA at 3.0 T versus 1.5 T for all b-values tested in white matter, with overall FA decreasing at high b. Field strength was found to be a significant main effect on the accompanying principal eigenvector coherence, also exhibiting a decreasing trend with increasing b. In summary, the improvement of SNR with field strength saw significant increase in white matter FA along with coherence.

                  1454.     Segmentation and Characterisation of White Matter Tracts in Late Childhood and Adolescence

Jonathan D. Clayden1, Catherine J. Riney1, Janine Cooper1, Monica Muñoz1, Chris A. Clark1

1Institute of Child Health, University College London, London, England, UK

This work describes the application of the recently-developed probabilistic neighbourhood tractography (PNT) method to data acquired from subjects in late childhood or adolescence. Using this method, we segmented a number of white matter tracts in each subject's data, and investigated the effects of age and gender on diffusion parameters. We found clear differences between the tracts, and we demonstrate some evidence for a lateralisation effect which is at least partly modulated by gender.

                  1455.     Micro-Architectural Features of the in Vivo Human Optic Chiasm

Joelle E. Sarlls1, Carlo Pierpaoli1

1NICHD, National Institutes of Health, Bethesda, MD, USA

Diffusion tensor images were acquired at sub-millimeter resolution, in-vivo, in the oblique plane of the optic nerves/chiasm/tracts. Acquiring data at sub-millimeter resolution dramatically reduces partial volume effects, allowing quantitative measures of the optic chiasm without CSF contamination and increased fiber coherence. In addition to the commonly calculated parameters of diffusion, measures of the diffusion ellipsoid’s shape were also calculated. We observe that there are not only architectural differences in the crossing and uncrossed fibers of the medial and latteral optic chiasm, but that the trajectory of crossing fibers may depend on their dorsal/ventral location in the chiasm as well.

                  1456.     Stability of Diffusion Direction Based Thalamus Segmentation

Sarah C. Mang1, Uwe Klose1, Susanne Reiterer1,2, Wolfgang Grodd1

1Section Exp. MRI of CNS, Diagnostic and Interventional Neuroradiology, Tübingen, Germany; 2Hertie Institute for Clinical Brain Research, General Neurology, University of Tübingen, Tübingen, Germany

A simple diffusion direction based segmentation method was used to distinguish thalamic sub-structures on 53 healthy volunteers. This segmentation method classifies voxels according to the orientation of their principal diffusion direction. The results of this simple segmentation method were stable in the evaluated subject population. Our segmented clusters did in addition show a correspondence to the clusters segmented with a more complicated connectivity based segmentation approach.

                  1457.     Detection of Motor Thalamus by Probabilistic Diffusion Density : Verification by Motor BOLD-Based FMRI

Tzu-chen Yeh1, Zong-Kai Hsu2, Sue-Jin Lin2, Chou-Ming Cheng1, Jen-Chuen Hsieh2, Low-Tone Ho1

1Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan, Taiwan; 2Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan, Taiwan

Structural MRI and functional MR data with motor task of right index were obtained from fourteen normal subjects. Thalamal parcellation by probabilistic diffusion density tractography (PDD) was performed with two protocols. Protocol I applied the Brodmann areas 1-6 as targets in normalized space. And protocol II used the central correlates of motor fMRI as target. Two similarity indices of thalamus parcellation were calculated as SI(BA1-6) = 0.56and SI(motor-fMRI) = 0.96 regarding to protocol I and II, respectively. We concluded the PDD-based parcellation of motor thalamus can be validated by using the fMRI of a simple motor task.

                  1458.     Mapping the Human Connectome at Multiple Scales with Diffusion Spectrum MRI

Leila Cammoun1, Xavier Gigandet1, Olaf Sporns2, Jean-Philippe Thiran1, Kim Q. Do3, Philippe Maeder4, Reto Meuli4, Patric Hagmann1,4

1Signal Processing Laboratory 5, Ecole Polytechnique Fédérale de Lausanne, Lausanne, VD, Switzerland; 2Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA; 3Center of Psychiatric Neuroscience, University Hospital Center and University of Lausanne (CHUV), Lausanne, VD, Switzerland; 4Department of Radiology, University Hospital Center and University of Lausanne (CHUV), Lausanne, VD, Switzerland

We propose to map the human connectome by constructing normalized whole-brain structural connection matrices derived from diffusion spectrum MRI tractography at 5 different scales. These connection matrices are then examined across scales for several important network characteristics. We show that key network measures can be robustly estimated across multiple scales with results that are consistent with previous single-scale investigations. In particular, we confirm that cortical networks exhibit exponential distributions of node degree and fiber densities, robust small world characteristics, as well as consistent estimates for node centrality at all scales examined.

                  1459.     Cingulum Bundle Asymmetry Predicts Trait Neuroticism: A DTI Study

Kathrine Skak Madsen1,2, Terry L. Jernigan1,2, Arnold Skimminge1,3, Erik Lykke Mortensen2,4, Gitte M. Knudsen2,5, William F.C. Baaré1,2

1Danish Research Center for Magnetic Resonance, Copenhagen University Hospital, Hvidovre, Copenhagen, Denmark; 2Center for Integrated Molecular Brain Imaging, Copenhagen, Denmark; 3DTU Informatics, Technical University of Denmark, Lyngby, Denmark; 4Department of Health Psychology, University of Copenhagen, Copenhagen, Denmark; 5Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark

Amygdala and subgenual cingulate are linked to anxiety and mood disorders, for which the trait neuroticism is a risk factor. Left and right subgenual cingulate functional imbalances may contribute to behavioural and physical symptoms observed in depression. We investigated associations between neuroticism and cingulum FA in 45 healthy adults. DWI images were processed with TBSS to align main fibre tracts and ROIs were drawn in right and left cingulum. As hypothesized, cingulum FA laterality index (asymmetry) significantly predicted neuroticism. It is unclear whether cingulum FA asymmetry is a possible marker of increased risk of developing anxiety and mood disorders.

                  1460.     High Resolution Diffusion-Weighted Imaging Showing Radial Anisotropy in the Human Cortex in Vivo

Robin Martin Heidemann1, Alfred Anwander1, Thomas R. Knösche1, Thorsten Feiweier2, Fabrizio Fasano3,4, Josef Pfeuffer5, Robert Turner1

1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; 2Siemens Healthcare Sector, Erlangen, Germany; 3Fondazione Santa Lucia, Rome, Italy; 4Siemens Medical Solutions, Milano, Italy; 5Siemens Medical Solutions, Charlestown, MA, USA

High resolution diffusion-weighted imaging is affected by blurring due to T2* relaxation and geometrical distortions due to off-resonance effects. A combination of a zoomed approach and parallel imaging enables one to achieve high acceleration factors which are essential to obtain high resolution diffusion–weighted images with minimal distortions. With the achieved image quality and an in plane resolution of 1 mm x 1 mm it is possible to show the radial anisotropy of the human cortex in vivo.

                  1461.     Gender Differences in Correlations of Regional White Matter Integrity with Intelligence Factor Scores

Johnny Ng1, CheukYing Tang1,2, Emily Eaves1, Isabella Kanellopoulou2, Xinsu Mai1, David Carpenter1, David Schroeder3, Roberto Colom4, Richard J. Haire3,5

1Radiology, Mount Sinai School of Medicine, New York, NY, USA; 2Psychiatry, Mount Sinai School of Medicine, New York, NY, USA; 3Johnson O'Connor Research Foundation, Chicago, IL, USA; 4Universidad Autónoma de Madrid (UAM), Spain; 5School of Medicine, UC Irvine, Irvine, CA, USA

We studied correlations between regional white matter integrity, using DTI with a Siemens 3T Allegra, and intelligence factor scores with gender effect in 40 control subjects. Fractional anisotropy (FA) and directional color maps were computed using in-house software. Region of Interests were defined on color-coded maps. FA values were extracted and merged with intelligence factor scores for correlation analysis. Significant positive and negative correlations were detected. These findings were consistent with a recent report on DTI/IQ correlations on subjects 5-18 where correlations were negative in males and positive in females as they aged. Our results confirmed these findings into adulthood.

                  1462.     Diffusion Tensor Imaging at 7T: Expectations Vs. Reality Check

Oliver Speck1, Kai Zhong1

1Biomedical Magnetic Resonance, Otto-von-Guericke University, Magdeburg, Germany

In addition to strong T2 weighting, diffusion encoding reduces the signal significantly to encode the direction information. Therefore, DTI is notoriously SNR hungry and the use of very high field strength has been proposed to increase sensitivity. Despite the introduction of 7T, it is still not clear if 7T results in data quality improvement. The SNR gain in DTI measurements at 7T is estimated based on realistic tissue and imaging parameters. Large volume coverage DTI data have been acquired at 3T and at 7T and were compared. With current whole body gradients diffusion imaging at 7T is not superior to 3T.

Perfusion & Permeability:  DSC-MRI
Exhibit Hall 2-3                    Wednesday 13:30-15:30

                  1463.     Defining Arterial Input Function (AIF) in DSC-MRI: From Global to Local

Qing Ji1, John O. Glass1, Wilburm E. Reddick1

1Radiological Science, St.Jude Children's Research Hospital, Memphis, TN, USA

We propose a novel method to automatically extract local AIF from T2* weighted perfusion MRI. The local AIF was modeled as the convolution of a global AIF with a vascular transport function and incorporated into a pharmacokinetic model to fit the concentration-time course of the image voxels. We examined ten DSC perfusion MRIs from pediatric brain tumor patients and report initial results demonstrating that the proposed method can fit most voxels well and reconstructed local AIF maps not only show the time delay and dispersion of local vascular features, but also the typical cerebral blood flow pattern.

                  1464.     DSC-MR Perfusion: Leave Tracer Recirculation Alone

Jayme Cameron Kosior1,2, Richard Frayne2

1Electrical and Computer Engineering, University of Calgary, Calgary, AB, Canada; 2Seaman Family MR Research Centre, Foothills Medical Centre, Calgary, AB, Canada

A common misconception is that indicator dilution theory cannot be used to derive perfusion parameters such as cerebral blood flow (CBF) and cerebral blood volume (CBV) if tracer recirculation is present in dynamic susceptibility contrast MR perfusion data. Here, we show that it is unnecessary to remove tracer recirculation from DSC-MR data in order to derive perfusion parameters.

                  1465.     Improved Assessment of Regional Cerebral Blood Flow by Dynamic Susceptibility Contrast MRI Using a Kernel-Based Deconvolution Approach

Denis Peruzzo1, Gianluigi Pillonetto1, Alessandra Bertoldo1, Claudio Cobelli1

1Department of Information Engineering, University of Padova, Padova, Italy

A deconvolution operation must be performed to obtain the residue function (R(t)) in DSC-MRI images quantification. In this study, a kernel based deconvolution approach is proposed and validated on both simulated and clinical data. It tackles the problem in a fully Bayesian framework and includes information on both R(t) continuity and on the system BIBO stability. It has been shown to provide more physiological R(t) estimates and more accurate CBF values than SVD and cSVD. Furthermore, not only is DNP insensitive to the delay between the AIF and the C(t), but it can also estimate it.

                  1466.     Can a Human Operator Be Replaced by a Computer for Processing of Bolus-Tracking Perfusion Data?

Matus Straka1, Michael Mlynash2, Greg Zaharchuk1, Gregory W. Albers2, Roland Bammer1

1Lucas Center, Department of Radiology, Stanford University, Stanford, CA, USA; 2Stroke Center, Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA

Bolus-tracking DSC-MRI PWI is an important technique in acute stroke, but its use in clinical routine is hampered by need of manual processing. We have developed a fully automated system aimed on perfusion processing. A key part of the system is the automated selection of AIF and VOF signals in the data. In this study, we compared manual and automatic selections on 30 cases with focus on noisy data and data with motion. The results indicate high success (>90%) rate of the system on various bolus-tracking datasets and allow usage of such algorithm in clinical routine.

                  1467.     Estimation of CBF Values Using Multi-Echo DSC-MRI:  a Comparison with a Xenon CT

Matus Straka1, Greg Zaharchuk1, Rexford David Newbould2, Gregory W. Albers3, Michael E. Moseley1, Roland Bammer1

1Lucas Center, Department of Radiology, Stanford University, Stanford, CA, USA; 2GlaxoSmithKline, London, UK; 3Stroke Center, Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA

Standard PWI acquisitions using single-echo EPI suffer from various errors (e.g. vascular signal clipping and counfound determination of quantitative perfusion values). Advanced acquisition schemes (e.g. PERMEATE) as well as corrections for partial volume effect and susceptibility effect of tracers in bulk blood were proposed to mitigate the problems. In this study, we have compared CBF perfusion maps computed from multi-echo parallel EPI sequences with values from XeCT CBF maps. We conclude that multi-echo acquisition contribute to better estimates of the quantitative parameter, but the improved acquisition opened a whole new set of challenges that were important before.

                  1468.     Limitations of a Multiplicative Correction of Partial Volume Effects on the Arterial Input Function in Bolus-Tracking Perfusion

Adam Espe Hansen1, Henrik Pedersen1, Egill Rostrup1, Henrik BW Larsson1

1Functional Imaging Unit, Glostrup Hospital, Glostrup, Denmark

The partial volume effect (PVE) on the arterial input function (AIF) remains a major obstacle to absolute quantification of cerebral blood flow (CBF) using MRI. This study evaluates the validity and performance of a commonly used multiplicative rescaling of the AIF to correct for the PVE. In a group of six patients, perfusion imaging was performed using a T1-weighted approach. Various degrees of PVE were induced on the AIF and subsequently corrected using a multiplicative AIF rescaling. Our results show that a multiplicative rescaling is not always applicable and can introduce a CBF bias. An easily measurable quantity denoted the tissue signal fraction (TSF) is proposed as a measure of the applicability of a multiplicative rescaling. For the present CBF quantification method a TSF of less than 0.4 results in a CBF bias below 15% after AIF rescaling.

                  1469.     Dynamic Susceptibility MRI with a Pre-Bolus Administration Design for Improved Absolute Quantification of Perfusion

Linda Knutsson1, Anna Rydhög1, Danielle van Westen2, Stig Holtås2, Freddy Ståhlberg2,3, Ronnie Wirestam1

1Department of Medical Radiation Physics, Lund University, Lund, Sweden; 2Department of Diagnostic Radiology, Lund University, Lund, Sweden; 3Department of Medical Radiation Physics, Lund University , Lund, Sweden

Reproducible absolute quantification of cerebral blood volume (CBV) and cerebral blood flow (CBF) by dynamic susceptibility contrast MRI (DSC-MRI) is difficult to achieve, for example, due to partial-volume effects (PVEs). The purpose of this study was to correct for arterial PVEs by rescaling the AIF using a VOF obtained by injecting a fraction of the contrast-agent dose as a pre-bolus. During the pre-bolus passage, a segmented EPI sequence in single-slice mode was used to register the VOF in the superior sagittal sinus. Our results showed that our proposed correction method removed a substantial amount of arterial PVEs.

                  1470.     Estimation of Perfusion and Other Vascular Parameters from First Part of Bolus Passage

Lars G. Hanson1, Henrik Lund1, Irene K. Mikkelsen2

1Danish Research Centre for MR, dept. 340, Copenhagen University Hospital, Hvidovre, Denmark; 2Centre for Functionally Integrative Neuroscience, Århus University Hospital, Århus, Denmark

Vascular properties can be derived from dynamic measures of the

                  1471.     Dose Optimization for Combined Perfusion Weighed Imaging and Contrast Enhanced MRA Using Gadofosveset

Erik Søndergaard Poulsen1, Aage Kristian Olsen2, Dora Zeidler1, Niels Hjort1, Leif Østergaard1

1Center of Functionally Integrative Neuroscience (CFIN), University of Aarhus, Aarhus, Denmark; 2PET-center, Aarhus University Hospital, Denmark

We optimized the dose of novel Gd-based, intravascular contrast agent gadofosveset trisodium (Vasovist®, Bayer Schering Pharma. Berlin, Germany) for dynamic susceptibility contrast (DSC) MRI in the brain. In 40 kg anesthetized pigs, a dose of 0.0916 mmol/kg was shown to generate a similar signal drop as a standard 0.1 mmol/kg Gd-chelate (Gadovist 1.0®, Bayer Schering Pharma. Berlin, Germany) while generating good CNR on steady state MRA.

                  1472.     Quantification of Vessel Permeability by Modeling Contrast Agent Extravasation in Dynamic Susceptibility Contrast MRI of Brain Tumors

Yi-Ying Wu1, Wei-Shan Yang2,3, Yuan-Yu Hsu4, Ho-Ling Liu2,5

1Institute of Medical Physics and Imaging Science, Chang Gung University, Kwei-Shan , Tao-Yuan, Taiwan; 2Institute of Medical Physics and Imaging Science, Chang Gung University, Kwei-Shan, Tao-Yuan, Taiwan; 3Department of Radiology, Cheng Hsin Rehabilitation Medical Center, Taipei, Taiwan; 4Department of Medical Imaging, Buddhist Tzu Chi General Hospital, Taipei, Taiwan; 5MRI Center, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan

Disruption of BBB in brain tumors can cause errors in perfusion measurements using DSC MRI. This study proposed a model that takes both T1 and T2 effect of the contrast extravasations into account and at the same time incorporates the parameter of permeability-surface-area-product (PS). This model was applied in three DSC datasets of brain tumors at 3T. The resultant PS ranged from 0.28 to 0.74 min-1 in tumors, which was greater than in normal tissues. Tumor/white matter blood volume ratios were corrected (3.5-7.4 before and 1.6-4.4 after correction) by fitting DSC time curves to the proposed model.

                  1473.     Quantitative OEF Determination in Tumor Patients Using Additional DSC Measurements

Moritz Mie1, Maja Sohlin2, Johann Scharf3, Lothar Rudi Schad4

1Computer Assisted Clinical Medicine, Faculty of Medicine Mannheim,, University of Heidelberg, Mannheim, Germany; 2Medical Physics in Radiology, DKFZ, Heidelberg, Germany; 3Department of Neuroradiology, University Hospital, Mannheim, Germany; 4Computer Assisted Clinical Medicine, Faculty of Medicine Mannheim, University of Heidelberg, Mannheim, Germany

Tissue oxygenation is a very important factor in the field of neuroradiology. With the assistance of the oxygen extraction fraction (OEF) an estimation of tissue viability should be possible. In this work, we improved the present technique by using an additional independent dynamic susceptibility contrast (DSC) measurement that directly gives the amount of cerebral blood volume (CBV) which is an important parameter for stabilizing the OEF calculation. With this technique a difference in OEF between a healthy brain area and a tumorous one is observed.

                  1474.     Normative Blood Flow Values in the Posterior Fossa Using Quantitative Spin-Echo DSC Perfusion MRI

Jessy J. Mouannes1, Anahita Aghaei-Lasboo2, Amir H. Yassari3, Anindya Sen2, Aaron Skolnik3, Shahram Rahimi2, Timothy J. Carroll2,4, Bernard R. Bendok5, Matthew T. Walker2, Sandra W. Horowitz2, Ali Shaibani2

1Biomedical Engineering, Northwestern University , Chicago, IL, USA; 2Radiology, Northwestern University, Chicago, IL, USA; 3Feinberg School of Medicine, Northwestern University, Chicago, IL, USA; 4Biomedical Engineering, Northwestern University, Chicago, IL, USA; 5Neurological Surgery, Northwestern University, Chicago, IL, USA

The interest in cerebral perfusion imaging has increased in recent years, with the aim of accurately detecting brain tissue at risk of infarction. These efforts have resulted in the establishment of normal values for cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT), for the supratentorial section of the brain. However, without a quantitative understanding of normal flow values in the posterior fossa, it is difficult to make judgments on issues such as cerebrovascular reserve or chronic ischemia. Therefore, we have evaluated normative “quantitative” perfusion values for the posterior fossa in adults using the Bookend technique.

                  1475.     Dynamic Contrast Enhanced Whole Brain Perfusion Using a Rapid 3D T1-Weighted Sequence at 7T

Paul S. Morgan1,2, Emma C. Tallantyre3, Ali Al-Radaidah3, Jennifer E. Dixon4, Matthew J. Brookes4, Nikos Evangelou3, Peter G. Morris4

1Radiology & Radiological Sciences, Medical University of South Carolina, Charleston, SC, USA; 2Academic Radiology, University of Nottingham, Nottingham, UK; 3Clinical Neurology, University of Nottingham, Nottingham, UK; 4Sir Peter Mansfield MR Centre, University of Nottingham, Nottingham, UK

7T has shown potential in imaging the human brain. We investigated the feasibility of acquiring whole brain perfusion data during administration of a bolus of gadolinium-based contrast agent at 7T using a 3D T1-weighted technique previously demonstrated at lower field. Successful data were acquired on three patients with multiple sclerosis, yielding perfusion values for white and gray matter in the range obtained by other perfusion studies, indicating that this technique may be performed successfully at 7T.

                  1476.     Quantitative Cerebral Perfusion in Rodents Assisted by Susceptibility Weighted Imaging

Rui Liu1, Renjie He2, Kurt H. Bockhorst2, Venkata K. Mogatadakala2, Ponnada A. Narayana2

1Department of Electrical and Computer Engineering, University of Houston, houston, TX, USA; 2Department of Diagnostic and Interventional Imaging, University of Texas Medical School at Houston, Houston, TX, USA

Synopsis: A method for accurate determination of the perfusion parameters based on dynamic susceptibility contrast MRI is proposed and applied to determine the hemodynamic parameters in a rat brain. Our algorithm is based on the singular valued decomposition (SVD) technique. In addition, we registered SWI images with gradient-echo EPI images to identify and exclude venous structures for improved estimation of hemodynamic parameters. The hemodynamic parameters calculated using our procedure agrees with those determined using the microsphere technique, considered to be the “gold standard”.

                  1477.     Gas-Filled Microbubbles as Intravascular Susceptibility Contrast Agent for Brain MRI

Jerry S. Cheung1,2, April M. Chow1,2, Ed X. Wu1,2

1Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, China; 2Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, China

Gas-filled microbubbles have the potential to become a unique MR contrast agent due to their magnetic susceptibility effect, biocompatibility and localized manipulation via ultrasound cavitation. In this study, custom-made albumin-coated microbubbles and a commercially available lipid-based clinical ultrasound contrast agent SonoVue® were investigated with in vivo dynamic brain MRI in Sprague-Dawley rats at 7 Tesla. The results indicate that microbubbles can serve as an intravascular contrast agent for brain MRI at high field. Such microbubble MRI has the potential to provide real-time MRI guidance in various microbubble-based drug delivery and therapeutic applications.

                  1478.     Detection of Pulmonary Embolism with Hyperpolarized 3He MRI: A Comparison of PO2-Based and Susceptibility-Based Techniques

Michelle E. Law1, Jiangsheng Yu1, Stephen Kadlecek1, Kiarash Emami1, Masaru Ishii2, John MacDuffie-Woodburn1, Matthew Stetz1, Rahim R. Rizi1

1Radiology, University of Pennsylvania, Philadelphia, PA, USA; 2Department of Otolaryngology, Head and Neck Surgery, Johns Hopkins University, Baltimore, MD, USA

Hyperpolarized 3He MRI has been applied to diagnosis pulmonary emboli. In this work, we present a comparison of pO2-based and susceptibility-based hyperpolarized 3He MRI techniques for the detection of pulmonary emboli in a pig model. The experiment results show that the pO2-based technique is more sensitive than the susceptibility-based technique.

Perfusion & Permeability:  DCE-MRI
Exhibit Hall 2-3                    Thursday 13:30-15:30

                  1479.     An Automated Method for Determination of Arterial Input and Venous Output Function Using Perfusion Parametric Joint Histogram Analysis

Hiroyuki Kabasawa1, Tetsuji Tsukamoto1

1Japan Applied Science Laboratory, GE Yokogawa Medical Systems, Hino-shi, Tokyo, Japan

The automated arterial input and venous output function (AIF and VOF) is crucial to improve stroke diagnosis workflow and to reduce the variation of perfusion analysis result. The quality of AIF and VOF is also critical for perfusion quantification. We have developed the automated AIF/VOF detection algorithm based on the perfusion parametric joint histogram analysis. We showed that the VOF detection accuracy was significantly improved, by adding the averaged tracer concentration after bolus passages information into the joint histogram analysis.

                  1480.     Intravascular Water Molecule Lifetime in the Japanese Macaque Brain

Jeffrey Moses Njus1, James R. Pollaro1, Mathew T. Snodgrass1, John Cunneen1, Ethan Muldoon1, Vincent B. Warren2, Xin Li1, Charles S. Springer1, Steven G. Kohama2, William D. Rooney1

1Advanced Imaging Research Center, Oregon Health & Science University, Portland, OR, USA; 2Oregon National Primate Research Center, Beaverton, OR, USA

The purpose of this study was to investigate brain intravascular water molecule lifetime estimation using a dynamic contrast enhanced technique. MRI data were collected at 3T in the Japanese macaque. Gadoteridol (Gd) was administered and whole-brain quantitative R1 maps were collected using a sparse pharmacokinetic temporal sampling scheme during the contrast washout period. We compare intravascular water lifetimes extracted with and without accounting for Gd extravasation during the time series.

                  1481.     Simultaneous Imaging of Absolute CBF Change and BOLD with Saturation-Recovery-T1 MRI Approach Under Ischemia and Hypercapnia

Xiao Wang1, Xiao hong Zhu1, Yi Zhang1, Wei Chen1

1Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, USA

Apparent T1 is sensitive to cerebral perfusion, thus, CBF can be imaged by MR-based arterial spin labeling techniques. In this study, we proposed an alternative approach based on the saturation-recovery T1 imaging method for simultaneously measuring absolute CBF change (∆CBF) and BOLD. This perfusion approach was validated by examining the relationship between the simultaneously-measured ƒ´CBF using the MRI approach and relative percent CBF change using LDF in the rat brain under ischemia and hypercapnia conditions. The results suggest that the measured change in apparent T1 was tightly correlated to the absolute CBF increase during hypercapnia and decrease during ischemia. This perfusion approach, thus, should provide a useful, robust MRI tool for noninvasively imaging absolute CBF change and BOLD associated with brain physiology, function and viability.

                  1482.     Rapid and Direct Quantification of Longitudinal Relaxation Time (T1) in Look-Locker Sequences Using an Adaptive Neural Network

Hassan Bagher-Ebadian1,2, Ramesh Paudyal1,2, Tom Mikkelsen3, Quan Jiang1, James Russel Ewing1,2

1Neurology, Henry Ford Hospital, Detroit, MI, USA; 2Physics, Oakland University, Rochester, MI, USA; 3Neurosergery, Henry Ford Hospital, Detroit, MI, USA

In this study an adaptive neural network is employed for direct estimation of longitudinal relaxation time (T1) in Look-Locker signals. It is hypothesized that, given a signal generated by a LL model, an ANN could be trained to directly estimate T1. The analytical equation of the Look-Locker signal was considered as the gold standard of training and a set of LL signals for a wide range of T1’s were generated. For each T1 value LL signal inputs were generated by varying the other independent parameters in the synthetic model of signal (T2*, M0 etc).

                  1483.     Accuracy of Cerebral Blood Flow Measurements in Accelerated Dynamic Contrast Enhanced MRI Using k-T SENSE

Henrik Pedersen1, Adam Espe Hansen1, Henrik B.W. Larsson1

1Functional Imaging Unit, Glostrup Hospital, Glostrup, Denmark

Dynamic contrast enhanced (DCE) MRI represents an attractive technique for quantifying cerebral blood flow (CBF). However, the inherent slow nature of DCE-MRI currently prohibits whole-head imaging of CBF. This study investigates how different degrees of data reduction obtained with k-t SENSE influence CBF measurements in the brain. The results suggest that the optimum combination of training data size and acceleration factor is 11 training profiles and 8x acceleration, resulting in a net acceleration factor of 4.6. In practise, this allows increasing the spatial coverage of DCE-MRI from 4 slices with SENSE to 10 slices with k-t SENSE.

                  1484.     Dynamic Contrast Enhanced (DCE) MRI Metrices as a Predictor of Response in Head and Neck Cancers

Sushma Agrawal1, Rishi Awasthi2, Anup Singh3, Ram Kishore Singh Rathore3, Rakesh Kumar Gupta2

1Department of Radiotherapy, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India; 2Department of Radiodiagnosis, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India; 3Department of Mathematics and statistics, Indian institute of technology, Kanpur, Uttar Pradesh, India

DCE imaging prior to radiotherapy and three months of completion of radiotherapy were performed in 21 patients of locally advanced head and neck cancers.The DCE MRI parameters in terms of tissue blood flow (TBF), tissue blood volume (TBV), corrected TBV, bolus arrival time (BAT) and b were correlated with T, N, stage group of the patient and with response to treatment. TBF, TBV and corrected TBV were higher for higher T stage, but not for N stage, and overall stage group .These parameters were higher for complete responders than partial responders at both primary and nodes. Our study reflects TBF and TBV as predictors of outcome in head and neck cancer patients but needs validation in more patients to get a more robust conclusion

                  1485.     Concurrent Measurement of Brain Perfusion, Blood Volume and Blood Brain Barrier Permeability Using Dynamic Contrast Enhanced T1 -Weighted MRI

Henrik BW Larsson1, Frederic Courivaud2, Egill Rostrup1, Adam Espe Hansen1

1Functional Imaging Unit, Glostrup Hospital, Glostrup, Denmark; 2The Interventional Centre, Rikshospitalet, Oslo, Norway

The measurement of brain perfusion (CBF) and cerebral blood volume (CBV) is important when diagnosing and treating vascular, degenerative and neoplastic diseases. These diseases are often associated with an increase of blood brain barrier (BBB) permeability. Despite the widespread use of MR perfusion imaging based on bolus tracking a concurrent estimation of CBF, CBV and permeability has proved difficult to achieve. The present study shows that brain perfusion, brain blood volume and blood brain barrier permeability can be obtained concurrently from dynamic contrast enhanced T1 -weighted perfusion imaging. Perfusion was estimated by Tikhonov’s deconvolution method and blood volume and permeability were estimated by using Patlak’s method in 10 patients with brain tumors. The results point to the importance of considering the effect of BBB leakage on the CBV estimation.

                  1486.     Enhancement of Gas-Filled Microbubble Magnetic Susceptibility by Iron Oxide Nanoparticles

April M. Chow1,2, Jerry S. Cheung1,2, Ed X. Wu1,2

1Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, China; 2Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, China

Gas-filled microbubbles possess the ability to be an MR susceptibility contrast agent due to the induction of large local magnetic susceptibility differences by the gas-liquid interface. However, microbubble susceptibility effect is relatively weak when compared with other intravascular MR susceptibility contrast agents. In this study, we demonstrated that microbubble susceptibility effects can be improved by embedding and entrapping iron oxide nanoparticles, and hence microbubbles can be monitored with high sensitivity and low concentrations under MRI.

                  1487.     Single-Shot Look Locker T1 Mapping with Golden Angle Radial Sampling for Free-Breathing Liver DCE-MRI in Rats at 1.5 T

Andreas Steingoetter1, Jonas Svensson1,2, Rickmer Braren3, Rene Botnar1,4, Stefanie Remmele5

1Department of Nuclear Medicine, Klinikum rechts der Isar, Technische Universität München, Munich, Germany; 2Department of Medical Radiation Physics, Malmoe University Hospital, Lund University Malmoe, Malmoe, Sweden; 3Department of Radiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany; 4Division of Imaging Sciences, King’s College London School of Medicine, London, UK; 5Philips Research Europe-Hamburg, Hamburg, Germany

A 2D single-shot Look-Locker T1 mapping technique (LLRGC) applying golden angle radial sampling and dedicated contrast enhancing k-space filter has recently been proposed for DCE-MRI studies. Here, we evaluate this technique for non-triggered and free-breathing DCE-MRI experiments in rats. T1 variability, flip angle dependency and motion sensitivity were analyzed in-vitro and in-vivo. Modelling capability of acquired concentration curves was confirmed by calculating Ktrans and ve. Phantom T1 values match reference values and show no flip angle dependency. No impairing motion artefacts are observed in images and T1 maps of rat abdomen. Determined Ktrans and ve values correspond to literature values.

                  1488.     Developmental Analysis of Placental Vascularization Using Dynamic Contrast- Enhanced MRI

Stav Sapoznik1, Vicki Plaks1, Elina Berkovitz2, Rebecca Haffner-Krausz2, Michal Neeman1

1Biological Regulation, Weizmann Institute of Science, Rehovot, Israel, Israel; 2Veterinary Resources, Weizmann Institute of Science, Rehovot, Israel

The importance of the placental circulation has long been recognized and is exemplified by the correlation of fetal weight with placental size and blood flow. In the current study we applied macromolecular contrast-enhanced MRI for in utero assessment of placental function along pregnancy in mice. We were able to assess placental blood volume fraction, rate of contrast material enhancement, placental volume and fetal length. We evaluated normal placentas at different developmental stages, as well as strain specific differences. Additionally, we studied placental function during fetal resorption and the function of tetraploid placenta in complementation rescue of genetically modified mice.

                  1489.     Factor Analysis in Segmentation of 4D DCE-MRI Renal Studies

Borys Shuter1,2, Voreak Suybeng3, David A. Stringer4, Marica Cutajar5, Thomas Dissing6, Anni Eskild-Jensen7, Michael Pedersen8, Jørgen Frøkiær6, Jens Christian Djurhuus6, Ashraf Kassim3, Shih-Chang Wang1, Isky Gordon5

1Diagnostic Radiology, National University of Singapore, Singapore, Singapore; 2Diagnostic Imaging, National University Hospital, Singapore; 3Electrical and Computer Engineering, National University of Singapore, Singapore; 4KK Women's and Children's Hospital, Singapore; 5UCL Institute of Child Health, London, UK; 6Institute of Clinical Medicine, University of Aarhus, Denmark; 7Department of Nuclear Medicine, Aarhus University Hospital, Denmark; 8Institute of Clinical Medicine, University of Aarhus,, Denmark

Temporal information inherent in 4D DCE-MRI may be utilised to segment anatomy of clinical interest. Factor analysis is shown to be able to isolate renal compartments and other abdominal and thoracic organs in clinical studies and a porcine model of renal obstruction.

                  1490.     DCE MRI Pixel-By-Pixel Quantitive Curve Pattern Analysis (CPA)

Junyu Guo1, Wilburn E. Reddick1

1Radiological Sciences, St. Jude Children's Research Hospital, memphis, TN, USA

A novel Curve Pattern Analysis (CPA) method is presented for DCE-MRI data processing. The CPA method characterizes and quantifies the DCE-MRI signal curves without prerequisites such as AIF and T1 measurement. The simulations show that the CPA parameters are stable and approximately insensitive to the baseline T1 value, TR and flip angle. In vivo study shows that the CPA parameter &[kappa] is very sensitive to the curve pattern and well correlated with the kinetic parameter kep. This method therefore could have a higher repeatability by eliminating effects from some variation factors, e.g. AIF and T1.

                  1491.     A Precise Model for Arterial Input Functions of First Pass DCE-MRI

Jeiran Jahani1, Glyn Johnson2

1Bioimaging, New York University, New York, USA; 2Bioimaging, New York University, New York, USA

Diffusion-Perfusion Animal Studies
Exhibit Hall 2-3                    Monday 14:00-16:00

                  1492.     Orthogonal Diffusion Anisotropy Measurements in the Dorsal Third Ventricle of Adult Rat Brain Reveal Cerebrospinal Fluid Flow

Laura Nieto-Charques1, Pilar López-Larrubia1, Sebastián Cerdán1

1Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM, Madrid, Spain

Diffusion Weighted Magnetic Resonance Imaging (DW-MRI) provides information on the microstructure of tissues and its changes. However, the calculated ADC values may contain contributions from additional translational motions or flow. To investigate this aspect we measured water ADC in three orthogonal directions of the Dorsal Third Ventricle of rat brain during a live-sacrifice and low-high b value paradigms. We found that CSF flow through the head-feet direction of the D3V increased significantly the ADC determined in this direction for both low and high b value sequences. An isotropic diffusion pattern is found when impeding CSF flow by sacrificing the animals.

                  1493.     Deletion of the Brain-Specific Link Protein BRAL-1 Facilitates Extracellular Diffusion in the Mouse Corpus Callosum

Ivan Vorisek1,2, Lydia Vargova2,3, Lesia Dmytrenko1, Yoko Bekku4, Toshitaka Oohashi4, Eva Sykova1,2

1Department of Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, v.v.i., Prague, Czech Republic; 2Center for Cell Therapy and Tisue Repair, Charles University, 2nd Medical Faculty, Prague, Czech Republic; 3Department of Neuroscience, Charles University, 2nd Medical Faculty, Prague, Czech Republic; 4Department of Mollecular Biology and Biochemistry, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan

Besides morphological techniques, the structure of the nervous tissue may be revealed by the diffusion of substances in the extracellular space (ECS). The efficacy of extrasynaptic transmission between neurons and between neurons and glia is based on the diffusion of neuroactive substances in the ECS and depends on the diffusion properties of the ECS. Our previous studies revealed that changes in the extracellular matrix substantially affect the diffusion properties of nervous tissue. In the present study we examined three parameters describing the diffusion of molecules and neuroactive substances in the cortex and corpus callosum of BRAL1 positive and negative mice.

                  1494.     In Vivo Diffusion Tensor Magnetic Resonance Imaging and Fiber Tracking of the Mouse Brain

Laura-Adela Harsan1, Dominik Paul1, Susanne Schnell1, Bjorn W. Kreher1, Juergen Hennig1, Jochen F. Staiger2, Dominik von Elverfeldt1

1Department of Diagnostic Radiology, University Hospital Freiburg, Medical Physics, Freiburg, Germany; 2Department of Neuroanatomy, Institute for Anatomy and Cell Biology, Center for Neuroscience, Freiburg, Germany

In vivo DT-MRI and fiber tracking was used in the present study to describe major white matter fiber tracts of the mouse brain and also to identify for the first time non-invasively the rich connectivity between the amygdala and different brain regions. Beside the standard fiber tracking procedure we generated probability maps of connectivity with which it was possible to investigate – in a statistical sense - all possible connecting pathways between two seed points. We show here applications to determine the connection probability between regions belonging to the visual or limbic systems.

                  1495.     Diffusion Tensor Image Guided Histological Assessment of a Kainic Acid Rat Epilepsy Model Ex Vivo Utilizing Tract-Based Spatial Statistics Analysis

Alejandra Sierra1, Kimmo Lehtimäki2, Teemu Laitinen1, Jari Nissinen1, Asla Pitkänen1,3, Olli Gröhn1

1Department of Neurobiology, A.I. Virtanen Institute, University of Kuopio, Kuopio, Finland; 2Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute, University of Kuopio, Kuopio, Finland; 3Department of Neurology, Kuopio University Hospital, Kuopio, Finland

Epilepsy is a challenging disease for imaging due to heterogeneous, widespread and non-focal changes in the brain tissue. The present study diffusion tensor imaging (DTI) and tract-based spatial statistics (TBSS) analysis provides "anatomics" of the brain pathology during experimental epileptogenesis, revealing areas involved in the epileptogenic process in a kainic acid animal model. This technique has a great potential to serve as a robust screening method to guide tedious histological analysis aimed to reveal cellular alterations of neuronal pathways.

                  1496.     MRI Evaluation of Selective Disruption of the Blood-Brain Barrier by Photochemical Internalization

Michelle Zhang1, Steen J. Madsen1, Henry Hirschberg1,2, H Michael Gach3

1Health Physics, University of Nevada Las Vegas, Las Vegas, NV, USA; 2Beckman Laser Institute, University of California Irvine, Irvine, CA, USA; 3Research Imaging Facility, Nevada Cancer Institute, Las Vegas, NV, USA

T2- and T1-weighted post-contrast MRI scans were acquired at 7 T to evaluate blood brain barrier (BBB) disruption from treatment-induced edema and contrast volumes. Photochemical internalization (PCI) treatment, coupling the macromolecule Clostridium perfringens (Cl p) epsilon prototoxin with AlPcS2a-photodynamic therapy (PDT), was performed on non-tumor bearing inbred Fischer rats. The result of BBB disruption from PCI was compared with a control group receiving PDT-only. PCI was found to be highly effective for inducing selective and localized disruption of the BBB. The extent of BBB opening peaked on day 3 and was completed restored by day 18 after PCI.

                  1497.     Crossing Fibers in Lateral White Matter of the Cervical Spinal Cord Detected with Diffusion MRI  in Monkey Postmortem

Henrik Lundell1,2, Tim Dyrby1, Maurice Ptito1,3, Jens Bo Nielsen4

1Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital, Copenhagen, Denmark; 2Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, France, Denmark; 3School of Optometry, Univ Montreal, Montreal, QC, Canada; 4Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark

Mapping the white matter configuration of the spinal cord is of interest for understanding superspinal contribution to the generation of motion and coordination of muscles. Postmortem diffusion weighted MRI is a potent technique to investigate the microstructure of neuronal tissue. We have investigated fiber directions of the spinal cord in monkey using DT, Q-ball and PAS. Crossing fiber structures in the corticospinal tract was found using multi-fiber reconstruction techniques with good correlation to histological findings of terminating fibers.

                  1498.     Comparison of Cerebral Blood Flow as Measured by Arterial Spin Labeling and Cerebral Blood Volume as Measured by Micro-CT Imaging Over Regions of the Mouse Brain

Brige Paul Chugh1, Jason P. Lerch1, Lisa X. Yu1, R Mark Henkelman1, John G. Sled1

1Toronto Centre for Phenogenomics, Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada

We developed an efficient imaging protocol to study the relationship between cerebral blood volume (CBV) and cerebral blood flow (CBF) over regions of the entire mouse brain, which may in future be applied to phenotype models of neurovascular disease. We performed a study that compared normative values of CBV and CBF over 13 mouse brain regions and over the cerebral cortex. The CBF was imaged using 3D arterial spin labeling and these images were co-registered to CBV images determined by a micro-CT protocol. This method could be useful for characterizing regional differences in vascularity in mouse models of cerebrovascular disease.

                  1499.     Temporal Tissue Assessment in Non-Human Primate Cerebral Ischemia Using Diffusion-Weighted MR Imaging and ISODATA Cluster Analysis

Mark J.R.J. Bouts1,2, Ona Wu1,3, Rick M. Dijkhuizen2, Alex J. de Crespigny1,3, Helen E. D'Arceuil1,3

1Athinoula A. Martinos center for biomedical imaging, Massachusetts General Hospital, Charlestown, MA, USA; 2Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands; 3Radiology, Massachusetts General Hospital, Charlestown, MA, USA

Non-human primate experimental stroke models allow for studying precisely timed evolutionary DWI stroke patterns, which appear similar to those seen in human stroke, without temporal MRI sampling restriction. In regional analysis partial volume artifacts and non-significant regional signal variations within the lesions can bias the analysis outcome.Therefore, in this study we applied an ISODATA analysis to elucidate on a voxel-by-voxel basis multiple evolutionary ADC/FA signatures in permanent vs transient MCA occluded macaque brains. Five distinct signatures were distinguished demonstrating the potential of voxel-by-voxel analysis in staging, identifying and quantifying ischemic tissue damage as a result of stroke.

                  1500.     Cerebral Hypoxia-Ischemia in Neonates as a Model of Ischemic Injury to Study MR Diagnosis of Descending Corticospinal Tract Degeneration

Sanju Lama1, Min Qiao2, Amy Ng1, Delphi Barua1, Dave Kirk1, Tad Foniok2, Ursula Irene Tuor1,2

1Experimental Imaging Center and Faculty of Medicine, University of Calgary, Calgary, AB, Canada; 2Institute for Biodiagnostics (West), National Research Council, Calgary, AB, Canada

Wallerian degeneration of the descending corticospinal tract (DCST) has been reported as a detection of increased signal intensities in Diffusion weighted imaging (DWI) following pediatric stroke. We hypothesized that a neonatal animal model of cerebral hypoxia ischemia and MRI may also detect such MR intensity changes. Seven day old rats were subjected to cerebral hypoxia-ischemia. Following the injury, T2 and DWI increased significantly in ipsilateral regions of the DCST including the cerebral peduncle and internal capsule.This is comparable to observations made clinically indicating the availability of an animal model to investigate details of MR diagnosis of CNS pre/Wallerian degeneration.

                  1501.     DTI Eigenvalues in Grey Matter: A Songbird's Perspective

Geert De Groof1, Marleen Verhoye1,2, Alexander Leemans3, Marcel Eens4, Veerle M. Darras5, Annemie Van der Linden1

1Bio-Imaging Lab, University of Antwerp, Antwerp, Belgium; 2Vision Lab, University of Antwerp, Antwerp, Belgium; 3Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, UK; 4Ethology Research Group, University of Antwerp, Antwerp, Belgium; 5Animal Physiology and Neurobiology Section, K.U. Leuven, Leuven, Belgium

This study investigates seasonal changes of grey matter in the songbird brain using Diffusion Tensor Imaging (DTI). Here we focused on the nuclei of the 'social behaviour network' and a auditory sensory processing region. Nine male starlings were measured in both the breeding and the non-breeding season. We found a decrease of the third eigenvalue from the diffusion tensor from breeding to non-breeding season in all regions demonstrating a change in aromatase expression. This indicates that not only the song control system changes between seasons but other relevant structures in the brain also.

                  1502.     ABCDEFGHI:  Anatomic Basis Construction for Dynamic Enhancement Following Gadolinium CHelate Injection

Dustin K. Ragan1, James A. Bankson1

1Imaging Physics, M. D. Anderson Cancer Center, Houston, TX, USA

Dynamic Contrast Enhaced (DCE) MRI measures the time course of a contrast agent in blood and tissue to investigate microvasculature. The measurement in the blood is challenging, particularly in small animal models, because of the small size of blood vessels and the fast kinetics of the agent in the bloodstream. We have developed a novel reconstruction technique which permits reconstruction of the signal in a ROI from a single phase encode line. Using this technique we have performed high temporal resolution measurements of the blood time course in the heart which are free of partial volume effects.

                  1503.     Physiological Motion Artifact Correction in Segmented DTI Measurement of Anesthetized Non-Human Primates

Shiliang Huang1, Xiaodong Zhang1

1Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA

DTI images are very vulnerable to any motion during scanning. Physiological motion is the dominant motion source in anesthetized non-human primate subjects, severely corrupting the images and compromising the quantitative interpretation of DTI data. In this paper, we present a simple strategy to recover the corrupted segmented EPI images in DTI measurement for non-human primates, without the need for modifying pulse sequences or acquiring additional data.

                  1504.     Diffusion Tensor Imaging Reveals White and Gray Matter Modifications After Low Dose 56Fe Irradiation

Lei Huang1, Shu-Wei Sun1,2, Sheng-Kwei Song3, Peter Hayes1, Andre Obenaus1,4

1Radiation Medicine, Loma Linda University, Loma Linda, CA, USA; 2Biomedical Engineering, Loma Linda University, Loma Linda, CA, USA; 3Radiology, Washington University, Saint Louis, MO, USA; 4Radiology, Loma Linda University, Loma Linda, CA, USA

Neuro-degeneration is one of the major health concerns following high-energy charged particles (HZE) radiation in space travel. In a rat model of 56Fe irradiation simulating the space environment, we assessed brain alterations in white and gray matter at 18 mo post-exposure of 0 – 4 Gy irradiation using DTI. The profiles of DTI-derived parameters, including Tr, RA, axial and radial diffusivity differed in the corpus callosum, hippocampus, substantia nigra and cortex. The results suggest that the sensitivity of DTI detects disturbances in white matter and gray matter which may both contribute to the progressive cognitive impairments following brain irradiation.

                  1505.     Magnetic Resonance Techniques Applied to the Study of Mouse Brain Complications in Sepsis

Philippe Garteiser1, Sabrina Doblas1, Fernando A. Bozza2, Marcus F. Oliveira3, Rebecca Cranford1, Debra Saunders1, Inna Jones1, Rheal A. Towner1, Hugo C. Castro-Faria-Neto2

1Advanced Magnetic Resonance Center, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA; 2Immuno-Pharmacology Laboratory, Oswaldo Cruz Foundation, Rio De Janeiro, Brazil; 3Medicinal Biochemistry, University of Rio De Janeiro, Rio De Janeiro, Brazil

Despite the high mortality and incidence of sepsis-associated encephalopathies, little in vivo evidence is available on the physiology of the septic brain. Especially, magnetic resonance techniques have only recently garnered interest in this domain even though their relevance to other encephalopathies is already demonstrated. Using T2-weighted imaging, apparent diffusion coefficient (ADC) mapping and localized spectroscopy of mice with a cecal ligation and puncture model of sepsis, we observed several distinctive features having a strong correlation to animal survival. In particular, changes were detected in the metabolic profile, brain basal vasculature integrity and tissue ADC of septic animals.

                  1506.     MRI Techniques to Measure RCBF in Experimental Cortical Impact Injury in Mice

Danielle Christa Brink1, Brittany Renshaw Bitner2, Leela Cherian1, Robia G. Pautler2, Claudia S. Robertson1

1Neurosurgery, Baylor College of Medicine, Houston, TX, USA; 2Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA

Traumatic brain injury (TBI) results in potentially severely compromised cerebral vasculature and significantly reduced regional cerebral blood flow (rCBF). Here we explore the effect of TBI on rCBF in mice using MRI techniques. Wildtype mice and transgenic mice deficient for the enzyme arginase were aneasthetized, intubated, and underwent severe cortical impact injury (3m/s; 1.5mm deformation). Imaging was done pre- and post-injury to assess changes in rCBF and injury site. Arginase deficient mice demonstrated overall higher reperfusion compared to wildtype mice suggesting that arginase is a key enzyme in the regulatory mechanism for recovery from TBI.

                  1507.     Multi-Slice Absolute Cerebral Blood Volume Quantification on Animal Model Using a Hybrid Method of Vascular Space Occupancy and Susceptibility Effect of MION

Chien-Chung Chen1, Young Ro Kim2, Yi-Chun Wu1, Chou-Ming Cheng3, Tzu-Chen Yeh3, Fu-Nien Wang1

1Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan, Taiwan; 2Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA; 3Integrated Brain Research Laboratory, Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan, Taiwan

A hybrid method combing the advantage of Vascular Space Occupancy, Dynamic Susceptibility Contrast imaging, and susceptibility induced R2 increase by long half-life contrast agent MION are proposed to measuring absolute cerebral blood volume (CBV) with multiple slices on animal model. The correlation between these method are high and therefore a regression can be utilized to convert multi-slices relative CBV values to absolute quantifications, which could be beneficial to measuring whole brain perfusion on animal experiments.

                  1508.     Diffusion Tensor Tractography Aids in Anatomical Phenotyping

Jacob Ellegood1, Ameet S. Sengar2, Michael W. Salter2, Sean E. Egan3, Jason P. Lerch1, R Mark Henkelman1

1Mouse Imaging Centre, Hospital for Sick Children, Toronto, Ontario, Canada; 2Neuroscience and Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada; 3Developmental Biology, Hospital for Sick Children, Toronto, Ontario, Canada

Diffusion Tensor Imaging (DTI) of fixed mouse brain is useful in examining development and genetic differences between wild type and knockout mouse models. Tractography using DTI, allows a qualitative visualization of changes in the morphology of white matter and has had limited use in mouse phenotyping. The purpose of this study was to assess anatomical changes non-invasively in the white matter of a genetically altered mouse model with associated white matter abnormalities.

Arterial Spin Labeling
Exhibit Hall 2-3                    Tuesday 13:30-15:30

                 1509.     Delayed Arrival of Arterial Blood Measured with Arterial Spin Labeling in Patients with a Symptomatic Carotid Artery Stenosis

Reinoud Pieter Harmen Bokkers1, H. Bart van der Worp2, Willem P. Mali1, Jeroen Hendrikse1

1Department of Radiology, UMC Utrecht, Utrecht, Netherlands; 2Department of Neurology, UMC Utrecht, Utrecht, Netherlands

Arterial spin labeling (ASL) with image acquisition at multiple delay times is able to measure the temporal dynamics of arterial blood inflow in addition to cerebral blood flow. The purpose of this study was to investigate the effect of a symptomatic stenosis in the internal carotid artery on the arrival of arterial blood measured with ASL. Herein, we found a delayed arrival of arterial blood in the hemisphere ipsilateral to ICA stenosis. ASL measurements of arterial blood inflow may provide valuable information on the hemodynamic changes in patients with an ICA stenosis.

                  1510.     Characterising the Origin of the Arterial Spin Labelling Signal in MRI Using a Multi-Echo Acquisition Approach

Jack A. Wells1,2, Mark F. Lythgoe2,3, Mankin Choy2,3, David Gadian2, Roger Ordidge1, David L. Thomas1

1Advanced MRI Group, University College London, London, UK; 2RCS Unit of Biophysics, UCL Institute of Child Health, London, UK; 3Centre for Advanced Biomedical Imaging, University College London, London, UK

ASL provides a means of isolating the MR signal from arterial blood water in the brain. We have measured the transverse decay of the ASL signal over a range of bolus durations and delivery times to estimate the dynamic origin of nutritive flow within the extra and intracellular tissue space in the rat brain. By taking measurements with and without vascular crusher gradients we have calculated the extent of the perfusion weighted signal originating from the cerebral vasculature. We hope that this technique may be useful for future application in animal models of disease to better understand the relationship between perfusion and pathology.

                  1511.     Reliable Isolation of the Intravascular Contribution in Arterial Spin Labelling MRI

Michael A. Chappell1, Bradley J. MacIntosh1, Nicola Filippini1,2, Matthias Günther3,4, Clare E. Mackay1,2, Peter Jezzard1, Mark W. Woolrich1

1Centre for Functional MRI of the Brain, University of Oxford, Oxford, UK; 2Department of Psychiatry, University of Oxford, UK; 3Univeristy Hospital Mannheim, University of Heidelberg; 4Advanced MRI Technologies, Sebastopol, CA

Multi-inversion time ASL is a potentially rich source of information about the cerebral blood flow, providing more than just CBF measurement alone. This study demonstrates that it is feasible to extract the intravascular contribution in ASL data that has not been subject to flow suppression. A probabilistic approach is used that allows Automatic Relevancy Determination to be implemented, avoiding over fitting with an arterial blood signal where none exists.

                  1512.     Optimization and Implementation of Vessel Suppression Preparation for ASL MRI

Weiying Dai1,2, Philip M. Robson1,2, Ajit Shankaranarayanan3, David C. Alsop1,2

1Radiology, Beth Israel Deaconess Medical Center, Boston, MA, USA; 2Radiology, Harvard Medical School, Boston, MA, USA; 3Applied Science Laboratory, GE Healthcare, Menlo Park, CA, USA

The presence of intravascular signal can have undesirable effects on image quality and perfusion values with arterial spin labeling (ASL) techniques. Bipolar gradients have been employed to attenuate the flowing labeled spins within spin or gradient echo echoplanar images. However, the insertion of bipolar gradients can be difficult or impossible in multiple RF refocused imaging sequences such as FSE and balanced SSFP. As an alternative, we optimized and implemented a preparation sequence before the image acquisition to eliminate the fast flowing spins. This preparation can be flexibly combined with any image acquisition.

                  1513.     Dispersion of a Short ASL Bolus Along the Arterial Tree

Matthias Günther1

1Neurology department, University Hospital Mannheim, University Heidelberg, Mannheim, Germany

In ASL, the inflow of labeled blood is usually modeled by assuming a single arrival time of the bolus in the voxel under consideration. However, it was shown that models, which assume a distribution of arrival times can fit some signal curves more accurately. The goal of this work is to show how a labeled blood bolus is dispersed while traveling down the arterial tree. A short bolus of 500ms length is used and sampled with 100ms temporal resolution. The broadening of this bolus is approximately proportional to the bolus arrival time. This tool might be a sensitive marker to detect local changes of hemodynamics.

                  1514.     Benefits of Short Bolus ASL

Matthias Günther1

1Neurology department, University Hospital Mannheim, University Heidelberg, Mannheim, Germany

Usually, a long labeled blood bolus is used in arterial spin labeling (ASL) to yield optimal signal-to-noise ratios in perfusion-weighted images. In this work, properties of short bolus ASL is examined and demonstrated. Benefits of this approach include the approximate measurement of the tissue response curve and the precise probing of properties of parts of the arterial tree. Based on the ASL data with a short bolus length BL data sets can be reconstructed with a virtual bolus length, which is a multiple of BL. This allows calculating ASL time series with a bolus length of e.g. 2500ms, which usually cannot be measured in reality. The deviation between true and calculated bolus is less than 1% for common parameters. Short bolus ASL might probe sensitive to changes due to neuro-degenerative or small vessel disease.

                  1515.     Theoretical and Experimental Comparison of Different Techniques for Continuous Arterial Spin Labelling

Rolf Pohmann1, Juliane Budde1, Edward Auerbach2, Gregor Adriany2, Kamil Ugurbil2

1Magnetic Resonance Center, Max-Planck-Institute for Biological Cybernetics, Tübingen, Germany; 2Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA

Several sequences for continuous arterial spin labelling have been proposed to overcome the technical and conceptual difficulties of this technique. Four different schemes for performing tag and control scans have been simulated for parameter optimization and implemented on a 3 T scanner. All sequences produced excellent perfusion images and were clearly superior to pulsed arterial spin labelling. Both simulations and experiments showed minor differences in SNR between the four techniques.

                  1516.     ASL Optimization for Hippocampus Physostigmine Challenge Perfusion Study

Xiufeng Li1, Subhendra Sarkar2, David M. Buhner3, Robert W. Haley4, Richard W. Briggs3,5

1Biomedical Engineering, UT Southwestern Medical Center, Dallas, TX, USA; 2Radiology, Beth Israel Deaconess Medical Center, Boston, MA, USA; 3Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA; 4Internal Medicine, UT Southwestern Medical Center , Dallas, TX, USA; 5Radiology, UT Southwestern Medical Center, Dallas, TX, USA

To better facilitate hippocampus physostigmine challenge perfusion studies using ASL technique, one optimization study was performed to determine proper post-bolus delay time by performing multiple inversion perfusion studies with fixed labeling time but varied post-bolus delay times for sessions with both saline infusion and PHY infusion. The study results indicate that post-bolus delay times equal to 1.0 s or 1.2 s give lower inter-subject variability of hippocampus CBF measurements for perfusion studies with both saline and PHY challenge. Hippocampus CBF measurements at post-bolus delay equal to 1.2 s showed the largest decrease in CBF with PHY infusion.

                  1517.     Modulated Dual Saturation Pulse Trains for FAIR Studies of Cerebellum Perfusion

Xiufeng Li1, Subhendra Sarkar2, Robert W. Haley3, Richard W. Briggs3,4

1Biomedical Engineering, UT Southwestern Medical Center, Dallas, TX, USA; 2Radiology, Beth Israel Deaconess Medical Center, Boston, MA, USA; 3Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA; 4Radiolody, UT Southwestern Medical Center, Dallas, TX, USA

When FAIR with Q2TIPS is applied for perfusion studies of specific brain regions, such as cerebellum, the superior labeled venous blood generates huge undesired artifacts, making CBF estimation in neighboring tissue unreliable. To avoid these adverse artifacts in cerebellum perfusion studies, a modulated dual saturation pulse trains for FAIR (MDS FAIR) technique was implemented and evaluated by performing perfusion studies in the cerebellum. The study results show that the MDS FAIR can greatly minimize these adverse venous artifacts. This technique should also be valuable for perfusion studies of other organs and tissues where similar problems exist.

                  1518.     Correcting for Off-Resonance Induced Degradation of Inversion Efficiency in Pseudo-Continuous ASL

Hesamoddin Jahanian1,2, Luis Hernandez-Garcia1,2, Douglas C. Noll1,2

1Functional MRI Laboratory, University of Michigan, Ann Arbor, MI, USA; 2Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA

Pseudo-continuous arterial spin labeing (pCASL) uses a long train of labeling pulses to provide multi-slice cerebral perfusion measurements while compensating for magnetization transfer effects without using additional hardware. Changes in local resonance frequency and field gradients, due to field inhomogenities, can compromise the tagging efficiency of pCASL, which causes loss in SNR and can lead to quantification error. Here we examine the efficacy of dynamically changing the residual gradient moment (h) to systematically compensate the unwanted changes in φ thus restoring the tagging efficiency of PCASL. The method is demonstrated using numerical simulation and In-vitro data.

                  1519.     Off-Resonant Artifact Correction of RF Pulse Concatenation for Blood Flow Imaging Applications

Cheng Ouyang1, Luis Hernandez2, Brad P. Sutton1,3

1Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA; 2FMRI Laboratory, University of Michigan, Ann Arbor, MI, USA; 3Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA

Concatenation of RF pulses holds great potential for allowing tag and saturation pulses to occur near imaging slices in arterial spin labeling scans or other blood flow imaging methods. However, concatenated RF pulses suffer from reduction of tag efficiency and improper control images when magnetic field inhomogeneity is present. In this abstract, we present a framework for correcting field inhomogeneity effects on the net flip angle of concatenated RF pulses. This framework will allow for future developments of blood flow imaging methods with saturation planes very close to or coincident with the imaging slices.

                  1520.     Continuous Arterial Spin Labeling at 9.4T: How Long to Label?

Hanbing Lu1, William Rea1, Elliot A. Stein1, Yihong Yang1

1National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA

A ¡°steady-state¡± condition has often been assumed in ASL quantification. However, when T1 values are remarkably increased at high fields, such as 9.4T, the steady-state condition may not be satisfied when the tagging duration is not sufficiently long. Two practical questions arise: 1) how long should the tagging duration be for reaching a steady-state at 9.4T; and 2) how much error could be potentially introdcued when such assumption is not satisfied. Theoretical analysis and eperimental data are presented. Results show that at 9.4T, short tagging duration (¡Ü4.8s) does not satisfy the ¡°steady-state¡± assumption, systematically underestimating resting-state perfusion values by ~30%. A correction procedure may be required.

                  1521.     Regional White Matter Perfusion Measurement Using an Optimized Pseudo-Continuous ASL MRI

Kun Lu1, Thomas T. Liu1, Eric C. Wong1, Youngkyoo Jung1

1Radiology, University of California San Diego, La Jolla, CA, USA

Measuring white matter perfusion using arterial spin labeling (ASL) MRI is challenging due to low SNR, partial volume and transit time effects. In this study we used an optimized pseudo-continuous ASL method to measure transit time and perfusion in major white matter regions across the brain. The optimized method offered significantly improved SNR compared to conventional pulsed and continuous ASL methods and enabled perfusion measurement in white matter. The partial volume effects were reduced by carefully selecting only regions of interest containing more than 90% of white matter. Our results indicated a wide spread of the white matter transit time and perfusion values. The mean transit time for whole brain white matter was 1394 msec and mean perfusion 23.6 ml/100g/min.

                  1522.     Optimization of the Encoding Scheme for Improved SNR Efficiency in Vessel Encoded Pseudo-Continuous ASL

Jia Guo1, Eric C. Wong2

1Bioengineering, UC San Diego, La Jolla, CA, USA; 2Radiology and Psychiatry, UC San Diego, La Jolla, CA, USA

In Vessel-Encoded Pseudo-Continuous ASL, encoding schemes with high SNR efficiency are important to correctly decode the vascular territory information. Hadamard type encoding is optimal, but it is not always obvious how to construct such a matrix. In this study, the tagging profile of VE-PCASL is measured from in vivo data, and fitted to a simple model. Based on this model, an encoding scheme with a small number of encoding steps to optimize the efficiency is achieved by configuring the encoding gradients such that the encoding matrix has columns from a Hadamard matrix under constrains such as gradient amplitude.

                  1523.     A Method for Automatic Selection of the Labeling Slabs in Regional Arterial Spin Labeling

Ina Kompan1, Matthias Günther1,2, Johannes Heitz3

1University of Heidelberg, Heidelberg, Germany; 2Universitätsklinikum Mannheim, Mannheim, Germany; 3mediri GmbH, Heidelberg, Germany

The method of regional arterial spin labeling allows to measure the cerebral perfusion of single feeding arteries. Selective positioning of the labeling slabs on the arteries of interest therefore must be accomplished. Manual selection of the slabs is operator-dependent. Here, a method is presented for automatic finding and positioning of the inversion slabs.

                  1524.     Reproducibility of Flow Territories Defined by Plannings-Free Vessel Encoded Pseudo-Continuous Arterial Spin Labeling

Sanna Gevers1, Aart J. Nederveen1, Reinoud P.H. Bokkers2, Jeroen Hendrikse2, Dennis A. Kies3, Wouter M. Teeuwisse3, C.B. Majoie1, Matthias J.P. van Osch3

1Radiology, Academic Medical Center, Amsterdam, Noord Holland, Netherlands; 2Radiology, University Medical Center , Utrecht, Netherlands; 3Radiology, Leiden University Medical Center, Leiden, Netherlands

Plannings-free selective arterial spin labeling MRI has the unique capacity to show the perfusion territories of brain feeding arteries non-invasively. The clinical applicability of this method is highly dependent on reliability and accuracy with which different flow territories can be identified. Therefore the aim of the present study was to determine whether RPI based flow territories are imaged sufficiently reliable and accurate to be used in a clinical setting.

                  1525.     Within and Between Session Reproducibility of MR Perfusion Using PICORE Q2TIPS at 3T

Yang Wang1, Andrew J. Saykin1, Chen Lin1, Kristine M. Mosier1, Andrew J. Kalnin1, Josef Pfeuffer2

1IU center for Neuroimaging, Department of Radiology, Indiana University School of Medicine, Indianapolis, IN, USA; 2Siemens Medical Solutions USA, Inc.

In this study, we evaluate within and between session reproducibility of perfusion MR using PASL sequence PICORE Q2TIPS, and compare results with and without physiological noise correction.

                  1526.     Double Acquisition Background Suppressed  (DABS) FAIR at 3T and 7T: Advantages for Simultaneous BOLD and CBF Acquisition.

Roman Wesolowski1, Penny A. Gowland1, Susan T. Francis1

1School of Physics and Astronomy, University of Nottingham, Sir Peter Mansfield Magnetic Resonance Centre, Nottingham, Nottinghamshire, UK

We have developed and optimised a Double Acquisition Background Suppression (DABS) method for simultaneous CBF and BOLD image collection using FAIR at 3 and 7T. Background suppression reduces physiological noise in ASL by acquiring images close to the null point, but this prohibits simultaneous BOLD acquisition. DABS is a new method which acquires a second BOLD weighted acquisition at the end of each TR period. We have used this technique to obtain qualitative maps of CBF and BOLD haemodynamic responses to a finger tapping task at both 3 and 7T. This technique improves the detection of CBF changes whilst retaining good BOLD contrast.

                  1527.     Background Suppression in Multi Slice Arterial Spin Labeling

Wouter M. Teeuwisse1,2, Maarten J. Versluis1,2, Mark A. van Buchem1,2, Matthias J.P. van Osch1,2

1Radiology, Leiden University Medical Center, Leiden, Netherlands; 2C.J.Gorter Center for High Field MRI, Leiden, Netherlands

In Arterial Spin Labeling, background suppression (BS) is known to enable a two fold increase in SNR of the perfusion images. However, for multi slice acquisition BS is only optimal for the first slice and will deteriorate in later slices due to regrowth of the background signal. In this study, efficiency of BS and its relation to SNR is investigated and also, whether addition of BS inversion pulses that are played between acquisition of slices improves BS and SNR for later slices.

                  1528.     Continuous Arterial Spin Labeling by a Separate Neck Coil with Inversion-Recovery Suppression of Static Tissue Signals (Ir-CASL)

Qiang Shen1, Timothy Q. Duong1

1Research Imaging Center, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA

Reduction or elimination of the static tissue signal in an ASL study could improve sensitivity and reproducibility. Such static tissue signal reduction has been achieved with the use of additional inversion pulses during the labeling of arterial spins in single-coil ASL techniques. In this work, we implemented the inversion-recovery suppression of static tissue to the two-coil continuous ASL (ir-cASL) to image baseline CBF and stimulus-evoked CBF fMRI. This approach compares favorably with existing methods because static tissue suppression is independent of labeling efficiency.

                  1529.     Improved Detection and Estimation of Perfusion Using High Spatial Resolution ASL at 7T

Emma Louise Hall1, Roman Wesolowski1, Penny A. Gowland1, Susan T. Francis1

1Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, Nottinghamshire, UK

Arterial Spin Labelling (ASL) data is typically acquired at coarse resolution with voxel volumes of ~ 50 ƒÝl. In this study the increased signal-to-noise and lengthened relaxation times at 7 T are used to acquire ASL at a range of spatial resolutions (45 ƒÝl, 27 ƒÝl, 12 ƒÝl and 7 ƒÝl). At high spatial resolution partial volume effects are reduced allowing the delineation of homogeneous grey matter perfusion changes. This leads to an increase in the measured mean grey matter ASL signal change, which will result in increased measured perfusion rate, and increased contrast-to-noise ratio.

                  1530.     Single Pair Arterial Spin Labeling Imaging

Jiabao He1, Andrew M. Blamire1

1Newcastle Magnetic Resonance Centre, Newcastle upon Tyne, Tyne and Wear, UK

Arterial spin labelling is a valuable MR technique to examine cerebral blood flow. Due to the small amplitude of contrast, a large number of acquisitions have to be collected, resulting in prolonged experimental duration. Two major sources of signal loss are T1 relaxation of tagged magnetization during transit between the labelling zone and imaging slice and T2* relaxation during imaging readout. In this work, we present a FAIR based technique to accelerate perfusion image acquisition through a combination of single slice imaging with a tightly restricted inversion slab to reduce transit region and spiral readout to mininize TE.

                  1531.     Comparison of Perfusion Values Obtained by Single Subtraction and Multiple Subtraction Strategies in ASL

Onur Ozyurt1, Alp Dincer2, Cengizhan Ozturk1

1Bogazici University, Biomedical Engineering Institute, Istanbul, Bebek, Turkey; 2Radiology Department, Acibadem University, School of Medicine, Istanbul, Turkey

In this study, voxel-wise comparison of CBF maps obtained from normal volunteers by single subtraction (SS)(typically, TI2 = 1400) and multiple subtraction (MS) experiments were done. It is shown that even for a healthy brain; SS method may result in underestimation in CBF in some voxels. Additionally, these voxels were identified as arterial sites and the regions with prolonged transit times. The amount of differences in CBF estimates of both methods are calculated.

                  1532.     Comparison of Breath Holding Techniques for the Calibration of FMRI Measurements of Oxygen Metabolism

Peter Roberts1, Peter Jezzard1, Daniel Bulte1

1FMRIB Centre, University of Oxford, Oxford, Oxfordshire, UK

Changes in the cerebral metabolic rate of oxygen consumption (CMRO2) during functional brain activity can be estimated from fMRI measurements of cerebral blood flow (CBF) and the blood oxygenation level dependent (BOLD) signal. A common method of calibrating the calculation uses breath holds to induce hypercapnia, which causes changes in cerebral blood oxygenation and flow. It has been debated whether it is better, either due to differences in physiology or magnetic field shim quality, to hold the breath after inspiration or expiration. The present study compared the two techniques by acquiring interleaved BOLD and CBF fMRI images from six subjects.

                  1533.     Measuring Absolute Arteriolar Cerebral Blood Volume (CBVa) in Human Brain Gray Matter (GM) Without Contrast Agent

Jun Hua1, Qin Qin1, James J. Pekar1, Peter CM van Zijl1

1Dept. of Radiology, The Johns Hopkins University, Baltimore, MD, USA

Vascular-space-occupancy (VASO) MRI can measure relative cerebral blood volume (CBV) without contrast agents using non-selective inversion to null blood signal. When spatially selective inversion is employed to null only blood flowing into a slice, signal can be sensitized to arteriolar CBV (CBVa) if a condition can be achieved for which blood-nulling time and arterial transit time are comparable. We show that absolute CBVa can be determined by performing such a scan with and without blood nulling followed by intensity-normalized subtraction. Measured CBVa in human GM was 0.96±0.18ml/100ml (n=7), in agreement with literature estimates.

                  1534.     3D Balanced SSFP Imaging of Arterial Arrival Time and Perfusion in Abdominal Organs Using Arterial Spin Labeling

Philip M. Robson1, Weiying Dai1, Ajit Shankaranarayanan2, David C. Alsop1

1Radiology, Beth Israel Deaconess Medical Center, Boston, MA, USA; 2Applied Science Laboratory, GE Healthcare, Menlo Park, CA, USA

Most studies using arterial spin labelling (ASL) for perfusion in the abdomen have used 2D acquisitions in a limited number of slices. We evaluated 3D balanced SSFP imaging for volumetric acquisition of abdominal perfusion. Subtraction ASL, with background suppression was used to obtain large field of view perfusion images in the abdomen, identifying perfusion in the renal parenchyma and in the spleen. Dynamic perfusion imaging measured the arrival time of blood to the tissues, employing continuous-labelling ASL that permits variable labelling times, independent of background suppression.

                  1535.     Assessment of Retinal and Choroidal Vascular Reactivity in Humans with Arterial Spin Labeling Perfusion Imaging

Nasim Maleki1, David C. Alsop2, Weiying Dai2, Chris Hudson3,4, David Mikulis1, Jay Han5, Joseph A. Fisher5,6

1Department of Medical Imaging, University of Toronto, Toronto, ON, Canada; 2Department of Radiology, Harvard Medical School and Beth Israel Deaconess Medical Center, Boston, MA, USA; 3School of Optometry, University of Toronto, Waterloo, ON, Canada; 4Department of Ophthalmology & Vision Science, University of Toronto, Toronto, ON, Canada; 5Department of Anesthesiology, University of Toronto, Toronto, ON, Canada; 6Thornhill Research Inc., Toronto, ON, Canada

Some of the major causes of irreversible vision loss are characterized by a pathophysiologic vascular dysfunction element. The feasibility of measurement of the total blood flow to the retina with an optimized arterial spin labeling method has been described previously. In the current study, we hypothesized that ASL can be used to measure the changes in flow to the combined retinal and choroidal system induced by hypercarbic and hyperoxic stimuli in human. Our results indicate that a CO2 provocation challenge in combination with the ASL may be a promising approach to investigate choroidal vascular reactivity under normal and disease states.

                  1536.     Layer-Specific Blood Flow MRI of the Mouse Retina

Eric Raymond Muir1,2, Timothy Q. Duong2

1Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA; 2Research Imaging Center, University of Texas Health Science Center, San Antonio, TX, USA

The retina is nourished by two separate blood supplies, the retinal and choroidal vessels. We previously reported blood flow MRI of the rat retina at 90x90 micron, but this resolution was insufficient to resolve the two vascular layers supplying the retina and the avascular layer in between. Herein, we developed the continuous arterial spin labeling technique for blood flow imaging of the mouse retina at considerably higher resolution (42x42 micron) to resolve the two vascular layers and the avascular layer in between. The effects of two common anesthetics, isoflurane or ketamine/xylazine, on blood flow in the retina were also examined.

                  1537.     Assessment of Calf Perfusion Kinetics in Response to Exercise and Ischaemia Using Q2TIPS-Arterial Spin Labelling Method

Elina Raja Ahmad1, Laura Michelle Parkes2, Graham J. Kemp1

1Magnetic Resonance & Image Analysis Research Centre (MARIARC), School of Clinical Sciences, University of Liverpool, Liverpool, UK; 2Imaging Science and Biomedical Engineering, School of Cancer and Imaging Sciences, The University of Manchester, Manchester, UK

Q2TIPS, a pulsed ASL variant, has technical advantages which have improved perfusion quantification in the brain. We report its first application to skeletal muscle, studying calf perfusion recovery kinetics after exercise and ischaemia. Four datasets were collected with 6 s resolution during recovery from 5 min cuff ischaemia (200 mmHg) in 5 subjects, and after 30s sustained 80% maximal plantar flexion in 4 subjects. Recovery kinetics after ischaemia and exercise were similarly fast (t½ 6±1, 7±2 s, respectively) indicating rapid vascular reactivity. Reproducibility of peak flow and t½ was good (CV 10-22%).

                  1538.     Comparing Kidney Perfusion Using Arterial Spin Labeling and Microsphere Methods in an Interventional Swine Model

Nathan Artz1, Andrew Wentland1, Elizabeth Sadowski2, Zhifei Wen1, Thomas Grist1,2, Arjang Djamali3, Sean Fain1,2

1Medical Physics, University of Wisconsin, Madison, WI, USA; 2Radiology, University of Wisconsin, Madison, WI, USA; 3Nephrology, University of Wisconsin, Madison, WI, USA

Two methods of measuring cortical kidney perfusion, fluorescent microspheres and ASL-FAIR, are compared for 5 swine at four time points: under baseline conditions, during an acetylcholine and fluid bolus challenge, and at baseline and after 2 hours of isoflurane anesthesia with ice placed on one of the kidneys. ASL correlates well with microspheres at every time point during the experiment, with a rho = 0.7.

                  1539.     ASL-FAIR Technique Optimization for Measuring Kidney Perfusion in Native and Transplanted Kidneys

Nathan Artz1, Zhifei Wen1, Yin Huang1, Sean Fain1,2

1Medical Physics, University of Wisconsin, Madison, WI, USA; 2Radiology, University of Wisconsin, Madison, WI, USA

An ASL-FAIR technique was optimized to measure cortical perfusion in native and transplanted kidneys. Motion compensation methods, kidney-specific T1 information, and a measured FAIR inversion factor are incorporated into perfusion measurement and calculation. Perfusion results with and without corrections are shown for two subjects (one transplant and one native) with diminished kidney function. Correction based methods are shown to affect the perfusion results by as much as 39%.

                  1540.     Perfusion Imaging of Inflammatory Thyroid Diseases Using an Arterial Spin Labeling Technique

Christina Schraml1, Karsten Müssig2, Petros Martirosian1, Nina F. Schwenzer1, Andreas Boss1, Claus D. Claussen3, Hans U. Häring2, Bernd Balletshofer2, Fritz Schick

1Department of Diagnostic Radiology, Section on Experimental Radiology, University Hospital of Tuebingen, Tuebingen, BW, Germany; 2Department of Internal Medicine IV, University Hospital of Tuebingen, Tuebingen, BW, Germany; 3Department of Diagnostic Radiology, University Hospital of Tuebingen, Tuebingen, BW, Germany

Thyroid inflammation pathologies are related to changes in thyroid tissue perfusion which cannot be quantified absolutely by the established imaging modalities. The aim of the present study was to investigate thyroid perfusion in autoimmune inflammatory thyroid diseases (Graves-Basedow and Hashimoto’s thyroiditis) by using an arterial spin-labeling approach working without contrast media administration. Perfusion maps of diagnostic quality were created by means of the extended Bloch equations. Perfusion values were calculated by ROI-analysis revealing significantly different perfusion values in the examined patient groups in comparison to healthy volunteers. Perfusion imaging may be helpful in diagnosis and monitoring of thyroid inflammation pathologies.