ISMRM 21st Annual Meeting & Exhibition 20-26 April 2013 Salt Lake City, Utah, USA

3029 -3052 Arterial Spin Labeling
3053 -3076 Perfusion & Permeability Measured with Contrast Agents
3077 -3100 Diffusion Applications
3101 -3123 Diffusion to Measure Perfusion
3124 -3147 Diffusion: Models & Microstructure
3148 -3171 Fiber ODF & Fiber Tracking
3172 -3195 Diffusion Acquisition & Analysis
3196 -3219 Diffusion MR Artefacts & Data Quality

Monday, 22 April 2013 (14:15-15:15) Exhibition Hall
Arterial Spin Labeling

  Computer #  
3029.   1 Pseudo-Continuous Arterial Spin Labeling Based Dynamic Angiographic Imaging with Decreased Number of Acquisitions
Onur Ozyurt1, Alp Dincer2, Ali Avci3, and Cengizhan Ozturk1
1Biomedical Engineering Institute, Kandilli, Istanbul, Turkey, 2Acibadem University, Kozyatagi, Istanbul, Turkey, 3Siemens Turkey, Kartal, Istanbul, Turkey

Pseudo-Continuous Arterial Spin Labeling (pCASL) based dynamic angiographic images were obtained with decreased number of acquisitions. An efficient labeling based on Hadamard encoding were used replacing the conventional control-tag pair imaging.

3030.   2 Prospective Motion Correction of 3D GRASE PASL Acquisitions with Volume Navigators
André J. W. van der Kouwe1,2, Matthew Dylan Tisdall1,2, Himanshu Bhat3, Borjan Gagoski2,4, and Keith A. Heberlein5
1A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, 2Radiology, Harvard Medical School, Boston, MA, United States, 3Siemens Medical Solutions, Charlestown, MA, United States, 4Center for Fetal-Neonatal Neuroimaging and Developmental Science, Boston Children's Hospital, Boston, MA, United States, 5Siemens Healthcare USA, Charlestown, MA, United States

3D GRASE PASL is a useful technique for efficiently measuring perfusion in clinical populations such as stroke patients. The technique is sensitive to motion because of the 3D segmented acquisition and successively acquired label and control volumes. This abstract describes an implementation of real-time prospective motion correction using embedded 3D EPI-based volume navigators. The method corrects rigid body head motions without increasing acquisition time and the motion corrected perfusion images are generated immediately on the scanner.

3031.   3 Pseudocontinuous Arterial Spin Labeling with Prospective Motion Correction (PCASL-PROMO)
Zungho Zun1, Ajit Shankaranarayanan2, and Greg Zaharchuk1
1Radiology, Stanford University, Stanford, CA, United States, 2GE Healthcare, Menlo Park, CA, United States

Arterial spin labeling (ASL) scans can benefit from motion correction techniques particularly for disoriented or uncooperative patients. Prospective motion correction (PROMO) is a rigid-body motion correction method based on image domain using 3-plane navigator. In this work, PROMO was incorporated into pseudocontinuous ASL (PCASL) sequences for cerebral blood flow (CBF) measurements. In the presence of brain motion, blurring artifacts were generated in ASL images, but these were removed dramatically using PROMO. In addition, ASL imaging was not perturbed by navigator imaging in PROMO and the labeling efficiency was not affected by the brain motion.

3032.   4 Pulsatile Motion Artifact Correction in Multishot Spiral PCASL
Li Zhao1, Samuel W. Fielden1, and Craig H. Meyer1,2
1Biomedical Engineering, University of Virginia, Charlottesville, Virginia, United States, 2Radiology, University of Virginia, Charlottesville, Virginia, United States

ASL is sensitive to motion, because of low SNR and control-label subtraction. Small blood flow changes can cause ring artifacts in multi-shot spiral ASL. The parallel reconstruction method SPIRiT removes aliasing by using multi-coil information and is proposed to reduce the artifact here. Volunteer PCASL images were reconstructed using conventional gridding method and using SPIRiT. By using SPIRiT parallel image reconstruction to reconstruct each spiral interleaf separately, the ring artifact resulting from pulsatile venous blood flow in multi-shot spiral ASL can be largely eliminated.

3033.   5 Improving ASL Using 3D bSSFP with Background Suppression and Two-Dimensional GRAPPA -permission withheld
Hua-Shan Liu1, Daeun Kim1, Randall B. Stafford1, Se-Hong Oh1, Sung-Hong Park2, Danny J.J. Wang3, Ze Wang1, Misung Han4, John A. Detre1, and Jongho Lee1
1University of Pennsylvania, Philadelphia, Pennsylvania, United States, 2Korean Advanced Institute for Science and Technology, Daejun, Korea, 3University of California, Los Angeles, LA, United States, 4University of California, San Francisco, San Francisco, California, United States

In this study, we investigated the characteristics of a 3D bSSFP sequence in ASL. We developed a BS-pCASL bSSFP with 2D (Ky and Kz) GRAPPA acceleration. The results were compared with conventional 2D EPI ASL. We demonstrated the advantages of a 3D BS pCASL-bSSFP sequence with high quality data while keeping the acquisition fast and efficient.

3034.   6 Benefits of Spiral Imaging for Arterial Spin Labeling as Compared to EPI -permission withheld
Britta Lehmann1, Tiejun Zhao2, and Josef Pfeuffer1
1Siemens Healthcare, MR Application Development, Erlangen, BY, Germany, 2Siemens Healthcare, Pittsburg, PA, United States

The most common imaging methods for PASL are EPI and spiral imaging. Segmenting the spiral trajectory into two interleaved spirals reduces the duration of each spiral and therefore blurring by off resonance effects. In this work, an approach with a one and a two-segmented spiral in comparison to full and partial k-space EPI were evaluated in terms of SNR and the impact of artifacts (off resonance, physiology) of the ASL signal. PICORE-PASL data from subjects were acquired in human subject at 3T. In conclusion, the two-segmented spiral method provided the bests result with regard to artifacts and SNR for PASL.

3035.   7 Feasibilty of Dual-Echo PCASL and PASL BOLD-RCBF fMRI in Olfactory Experiments
Ana Beatriz Solana1, Elena Molina2, Pablo García-Polo2, Juan Antonio Hernández-Tamames2,3, Susana Borromeo2, Fernando Zelaya4, and Francisco del Pozo1
1Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain, 2Universidad Rey Juan Carlos, Móstoles, Madrid, Spain, 3Fundación CIEN-Fundación Reina Sofía. Madrid, Madrid, Madrid, Spain, 4King's College London, London, United Kingdom

The study of the primary olfactory cortex with fMRI is difficult because of its location in medial temporal lobe, highly affected by magnetic field inhomogeneities causing both local image distortion and signal dropout. Arterial Spin Labelling is a promising fMRI technique, , above all in these distorted areas, due to its shorter TE and also because its a quantitative measurement. However, ASL-fMRI is challenging due to its low SNR. In this work, we showed the feasibility and advantages of using simultaneous dual-echo BOLD-ASL fMRI acquisition with spiral readout using PCASL and PASL in olfactory experiments in healthy volunteers.

3036.   8 Reproducibility of Total Cerebral Blood Flow and Determination of Tagging Efficiency in PCASL Using Gated and Non-Gated PCMRA
Yuxiang Zhou1,2, Lingyun Chen2, Xiaojun Sun1, Vipulkumar Patel1, Jerry S. Wolinsky3, and Ponnada A. Narayana1
1Department of Diagnostic and Interventional Imaging, University of Texas Medical School at Houston, Houston, TX, United States, 2Department of Diagnostic & Molucular Imaging, Beaumont Health System, Royal Oak, MI, United States, 3Department of Neurology, University of Texas Medical School at Houston, Houston, TX, United States

Tagging efficiency plays an important role in absolute CBF quantification based on (pseudo continuous arterial spin labeling (pCASL). In pCASL, the tagging efficiency strongly depends on the subject and other factors. Phase contrast MRA (PCMRA) is used for determining the tagging efficiency in a subject specific manner. Reproducibility of CBF and tagging efficiency were investigated by scanning the subject twice within one hour. No statistically significant differences between the mean of the two measurements was observed, suggesting excellent reproducibility. This study also demonstrates that non-gated PCMRA, which involves shorter scan times, is a reliable method for measuring the tagging efficiency.

3037.   9 Robust Perfusion Maps in Arterial Spin Labeling by Means of M-Estimators
Camille Maumet1, Pierre Maurel1, Jean-Christophe Ferré1,2, and Christian Barillot1
1Inria, IRISA, RENNES, Brittany, France, 2Department of Neuroradiology, CHU Rennes, Rennes, Brittany, France

In Arterial Spin Labeling (ASL), the perfusion signal is usually extracted by averaging the volumes acquired over several repetitions. Unfortunately, the presence of artefacts is a well-known source of outliers and can drastically alter the perfusion map obtained by averaging. In this paper, we propose to compute ASL perfusion maps using Huber's M-estimator, a robust statistical function that is not overly impacted by outliers. This method is compared to an empirical approach, previously introduced in the literature, based on z-score thresholding. Overall, Huber's M-estimator is more robust than z-thresholding. Both robust approaches outperform the sample mean in the presence of outliers.

3038.   10 Simultaneous Imaging of Cerebral Perfusion and Glucose Metabolism by PET/MRI
Udunna Anazodo1,2, R. Stodika1,2, John Butler1, Jonathan Mandel3, Terry Thompson1,2, F.S Prato1,2, Danny J.J. Wang4, and Keith, S St. Lawrence1,2
1Lawson Health Research Institute, London, Ontario, Canada, 2Medical Biophysics, Western University, London, Ontario, Canada, 3Radiology Department, St Joseph's Health Care, London, Ontario, Canada, 4Department of Neurology, UCLA, Ahmanson-Lovelace Brain Mapping Center, Los Angeles, California, United States

Objective of this study was to investigate the ability of a hybrid PET/MRI scanner to collect whole-brain images of cerebral perfusion and metabolism simultaneously by combining pseudo-continuous ASL with PET imaging of fluorine-18 fluoro-deoxyglucose (FDG) imaging. A strong correlation between regional cerebral blood flow and energy metabolism was found in two neurologically normal patients and one patient with traumatic brain injury. A perfusion/metabolism mismatch was found in a patient with frontotemporal dementia, similar to previous studies of Alzhemier’s disease.

3039.   11 Calibration of Cerebral Blood Oxygenation and Perfusion MR Imaging in Mice by Invasive Micro Probe Measurements.
Jan Sedlacik1, Matthias Reitz2, Div S. Bolar3, Elfar Adalsteinsson4, Nils Ole Schmidt2, and Jens Fiehler1
1Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, 2Neurosurgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, 3Radiology, A. A. Martinos Center, Charlestown, MA, United States, 4Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States

Quantitative MR measurements sensitive to blood oxygenation (R2*, QUIXOTIC-R2) and perfusion (Q2TIPS-ASL) were calibrated by different respiratory stimuli and subsequent invasive micro probe measurements. We found reasonable consistency between MRI and micro probe measurements. However, adverse effects of anesthesia and trauma during micro probe insertion have to be solved in further experiments.

3040.   12 Accuracy of Vessel-Encoded Pseudo-Continuous Arterial Spin Labeling in Identification of Feeding Arteries in Patients with Intracranial Arteriovenous Malformation
Songlin Yu1, Rui Wang2, Rong Wang1, Shuo Wang1, Yuqiang Yao3, Dong Zhang1, Yuanli Zhao1, Zhentao Zuo2, Rong Xue2, Danny J.J. Wang4, and Jizong Zhao1
1Tiantan hospital, Beijing, Beijing, China, 2Institute of Biophysics, Chinese Academy of Sciences, Beijing, Beijing, China, 3Beijing Jishuitan Hospital, Beijing, Beijing, China, 4University of California Los Angeles, Los Angeles, California, United States

In order to evaluate the diagnostic accuracy of VE-PCASL in identifying feeding arteries of intracranial AVM, sixteen AVM patients were examined with VE-PC ASL. Supply fraction of each feeding artery to the AVM was calculated. ROC curves were calculated to evaluate the diagnostic accuracy of VE-PCASL for identifying feeding arteries of AVMs, using DSA as the gold standard. Results are that for VE-PCASL with standard labeling efficiencies, the AUC was 0.935. The optimal cut-off of supply fraction for identifying feeding arteries was 15.17% and the resulting sensitivity was 83.3% and specificity was 91.7%. For VE-PCASL with custom labeling efficiencies, the AUC was 0.956. The optimal cut-off of supply fraction was 11.73% which yielded 88.9% sensitivity and 91.7% specificity. We conclude VE-PCASL with either standard or custom labeling efficiencies offers a high level of diagnostic accuracy compared to DSA for identifying feeding arteries.

3041.   13 Selective ASL with 2D RF Pulses
Britta Lehmann1, Dieter Ritter1, and Josef Pfeuffer1
1Siemens Healthcare, MR Application Development, Erlangen, BY, Germany

Different methods for selective labeling of single arteries have been developed for selective Arterial Spin Labeling. In this study, a spatially selective 2D-RF pulse was designed for a 2-channel pTX system and evaluated in human subjects. The pulse design used a variable-density TX trajectory, taking into account subject-specific B1 maps and hardware and SAR constraints. It was shown that these 2D-RF pulses can provide comparable results to the standard FOCI-PICORE method. The perfusion territories of the left internal carotid artery (ICA), right ICA and basilar artery were determined with a reasonable SNR even at small target sizes.

3042.   14 Full Brain and Territorial Arterial Spin Labeling with External RF Shimmed Labeling Coil at 7 Tesla
Wouter Koning1, Esben Thade Petersen1, Jaco J.M. Zwanenburg1, Peter R. Luijten1, and Dennis W.J. Klomp1
1University Medical Center, Utrecht, Utrecht, Netherlands

Arterial spin labeling (ASL) at ultra high field can theoretically offer a high signal to noise ratio (SNR) of the perfusion signal due to higher intrinsic SNR and the longer T1 relaxation times. A major challenge at 7T MRI is the absence of a body coil. Due to the limited range the head coils used at the 7 Tesla scanners, it is difficult to label the lower regions of the brain. In this research, a simple U-Tube transmitter is used as an external labelling coil, in combination with the standard head coil. With this setup, full brain and territorial ASL maps could be acquired.

3043.   15 Pulsed Continuous 3DASL Cerebral Perfusion Imaging Using Multiple Post Label Delay(PDL) Acq. in the Clinical Utility of Arterial Transit Time(ATT) Mapping: Comparative Study with PET-OEF in Patients with Chronic Occlusive Vascular Disease
Hirohiko Kimura1, Tetsuya tsujikawa1, Tsuyoshi Matsuda2, Yasuhiro Fujiwara3, Kennichi Kikuta4, and Hidehiko Okazawa5
1Radiology, University of Fukui, Fukui, Japan, 2Applied Science Laboratory Asia Pacific, GE Healthcare Japan, HIno, Japan, 3Radiology center, University of Fukui Hospital, Fukui, Japan, 4Neurosurgery, University of Fukui, Fukui, Japan, 5Biomedical Imaging Center, University of Fukui, Fukui, Japan

Arterial spin labeling (ASL) is a means of non-invasive MR perfusion assessment that provides a quantitative map of cerebral blood flow. However, it has not been fully investigated whether the hemodynamic changes in patients with occlusive cerebrovascular disease which affects the reliability of ASL-CBF value. The goal of the current study is to demonstrate arterial transit map calculation as well as CBF based on a two-compartment model using a 3DASL with multi-PLD approach. The comparison of CASL-ATT and O15 PET-OEF was also performed for the demonstration of clinical utility of ATT mapping in patients with chronic occlusive cerebrovascular disease.

3044.   16 Examining the Relationship Between Cerebral Blood Flood and Grey Matter Structure in Typically Developing Children
Jeffrey T. Duda1, Emily Kilroy2, James C. Gee1, Danny J.J. Wang2, and Brian B. Avants1
1Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2Neurology, University of California Los Angeles, Los Angeles, CA, United States

Cerebral blood flow is measured in typically developing children using pseudo-continuous arterial spin labeled MRI. Additionally, T1 and diffusion tensor images are acquired. Metrics derived from the structural images are used to create linear regression models in order to determine the extent to which structural properties of tissue account for variance in the measurement of cerebral blood flow in grey matter. The structural metrics examined include grey matter probability, white matter probability, cortical thickness, fractional anisotropy and mean diffusion.

3045.   17 Effect of NMDA-Receptor Inhibition on Relative Cerebral Blood Flow to the Hippocampus and Medial Prefrontal Cortex: A Placebo Controlled Repeated Measures Study of Ketamine in Healthy Young Men
Najmeh Khalili Mahani1, Marieke Niesters1, Matthias J.P. van Osch2, and Albert Dahan1
1Anesthesiology, Leiden University Medical Center, Leiden, Netherlands, 2Radiology, Leiden University Medical Center, Leiden, Netherlands

Pseudocontinuous ASL (pCASL) reveals regional effects of ketamine on relative cerebral blood flow in the hippocampus, basal ganglia, cerebellum and medial visual and prefrontal cortical regions.

3046.   18 Correlation Between Cerebral Blood Flow and Anisotropy in White Matter
Andrea Federspiel1, Sebastian Walther1, Ariane Orosz1, Roland Wiest2, Stéphanie Giezendanner1, Jennifer Andreotti1, Simon Schwab1, Thomas Dierks1, and Kay Jann1
1Dept. of Psychiatric Neurophysiology, University Hospital of Psychiatry / University of Bern, Bern, Bern, Switzerland, 2Institute of Diagnostic and Interventional Neuroradiology, University of Bern, Bern, Bern, Switzerland

In the present study the relationship between cerebral blood flow (CBF) and fractional anisotropy (FA) within white matter was investigated in a cohort of twenty four healthy subjects. After rigorous treatment of partial volume effects a significant negative linear relationship located within the splenium of the corpus callosum was observed between these variables in all subjects. The findings of the present study are in line with previous findings, but with a larger sample. The inverse relationship could indicate a dependency of CBF values with averaged axonal diameter of the tracts within WM.

3047.   19 Simultaneous Measurement of Perfusion and BOLD Changes in Calf Muscle During Exercise
Jason K. Mendes1, Christopher J. Hanrahan1, Gwenael Layec2, Corey Hart2, Russell S. Richardson2, and Vivian S. Lee3
1Radiology, University of Utah, Salt Lake City, Utah, United States, 2Internal Medicine, University of Utah, Salt Lake City, Utah, United States, 3School of Medicine, University of Utah, Salt Lake City, Utah, United States

Perfusion and oxygenation in calf muscle have been shown to be beneficial in determining severity of peripheral arterial disease and monitoring response to therapeutic interventions. However, imperfections in the saturation/inversion pulses used in ASL sequences cause significant errors in the measurement of perfusion. This works demonstrates the feasibility of modeling these imperfections in the calculation of perfusion.

3048.   20 Measurement of Reduced Lymphatic Flow Velocity Under Conditions of Obstructed Lymphatic Flow Using Spin Labeling Approach
Swati Rane1, Paula Donahue2,3, Theodore F. Towse1, Sheila Ridner4, John C. Gore1,5, Michael A. Chappell6,7, and Manus J. Donahue1,8
1VUIIS, Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States, 2Vanderbilt Dayani Center for Health and Wellness, Vanderbilt University Med. Center, Nashville, TN, United States, 3Vanderbilt Physical Medicine and Rehabilitation, Vanderbilt University Med. Center, Nashville, TN, United States, 4School Of Nursing, Vanderbilt University, Nashville, TN, United States, 5Biomedical Engineering, Vanderbilt University, Nashville, TN, United States,6Institute of Biomedical Engineering, University of Oxford, Oxford, OX, United Kingdom, 7John Radcliffe Hospital, Oxford Centre for Functional MRI of the Brain, Oxford, OX, United Kingdom, 8Psychiatry, Vanderbilt University, Nashville, TN, United States

This work tests the feasibility of our recently developed lymph spin labeling approach to study reduced lymphatic velocity in breast cancer treatment related lymphedema subjects

3049.   21 Perfusion Imaging of Renal Tumors at 3 Tesla Using Pulsed Continuous Arterial Spin Labeling
Ananth J. Madhuranthakam1, Ivan E. Dimitrov2, David C. Alsop3, and Ivan Pedrosa1
1Radiology and Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, United States, 2Philips Healthcare, Cleveland, OH, United States, 3Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, United States

We investigated pulsed continuous arterial spin labeling combined with background suppression for renal perfusion imaging at 3 Tesla using single shot fast spin echo acquisition. High image quality was achieved in normal volunteers and five patients with renal tumors. Averaged across all subjects, mean perfusion was measured as 235±72 mL/100g/min in cortex and 134±25 mL/100g/min in medulla and in agreement with values previously reported in the literature. Perfusion was heterogeneous in tumors and varied considerably across patients, most likely depending upon the tumor histopathologic subtypes.

3050.   22 Measurement of Renal Perfusion Using 3D Pseudo-Continuous Arterial Spin Labeling
Kaining Shi1, Haiyi Wang2, and Yehuan tang2
1Applied Science Lab (China), GE HealthCare, Beijing, Beijing, China, 2the Department of Radiology, People¡¯s Liberation Army General Hospital, Beijing, Beijing, China

3D Pseudo-Continuous Arterial Spin Labeling is a desirable approach for the measurement of renal perfusion because of its capability of providing noninvasive and non-contrast perfusion imaging. Compared to prior approaches, the 3D PCASL technique exhibits more uniform perfusion images with better SNR and lower SAR. In this work, 3D PCASL technique was successfully implemented in the measurement of kidney perfusion and renal blood flow was calculated. Perfusion weighted images with 2025ms PostLabelDelay time had better CNR and background suppression. Mean renal blood flow of the kidney cortex is about 0.5015 ml/min/g, similar to prior PET results.

3051.   23 A Double-Excitation Approach Is the Optimal Strategy for Whole-Brain ASL/BOLD Acquisitions
Vincent J. Schmithorst1,2, Luis Hernandez-Garcia3, Jennifer Vannest2, Akila Rajagopal2, Gregory Lee2, and Scott Holland2
1Radiology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, United States, 2Radiology, Children's Hospital Medical Center, Cincinnati, OH, United States, 3Functional MRI Laboratory, University of Michigan, Ann Arbor, MI, United States

The optimal approach for simultaneous ASL/BOLD imaging covering the whole brain is unknown. Via simulations, we compared relative ASL and BOLD CNR obtained using three possible acquisition strategies. Optimal performance was obtained using a dual-excitation approach, in which images with a short TE for ASL contrast are obtained immediately after the ASL tagging pulse; afterwards, images with a longer TE for BOLD contrast are acquired. Compared to a dual-echo acquisition, the dual-excitation strategy with optimized excitation flip angles provided a near 70% increase in ASL CNR for later-acquired slices, with only a 1% reduction in BOLD CNR.

3052.   24 Comparison of Multi-Parametric ASL and CT Perfusion in Moyamoya Diseases
Rui Wang1, Songlin Yu2, Jeffry R. Alger3, Bo Wang1, Jizong Zhao2, Zhentao Zuo1, Rong Xue1, and Danny J.J. Wang3
1State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, Beijing, China, 2Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, Beijing, China, 3Department of Neurology, University of California Los Angeles, Los Angeles, CA, United States

The goal of this study was to present a novel multi-delay multi-parametric pseudo-continuous ASL (pCASL) protocol which allows simultaneous estimation of cerebral blood flow (CBF), arterial cerebral blood volume and arterial transit time (ATT). Its accuracy was compared with CT perfusion (CTP) in 17 moyamoya patients. Based on both intra- and inter-subject correlation analysis, pCASL and CTP provided highly consistent results for the evaluation of hemodynamics in moyamoya patients. By incorporating delayed ATT in CBF calculation, pCASL is able to provide quantitative multi-parametric perfusion imaging consistent with CTP in moyamoya disease.


Monday, 22 April 2013 (15:15-16:15) Exhibition Hall
Perfusion & Permeability Measured with Contrast Agents

  Computer #  
3053.   1 The Influences of Vertebral Level and Age on Perfusion Parameters of Thoracic-Lumbar Vertebral Marrow in Adults Using T1-Weighted Dynamic Contrast Enhancement MRI
Qinxiang Li1, He Wang2, and Yunfei Zha1
1REN MIN HOSPITAL OF WUHAN UNIVERSITY, WUHAN, HUBEI, China, 2MR Research China, GE Healthcare, Shanghai, China

This study investigated the differences in quantitative perfusion parameters of thoracolumbar vertebral bone marrow(VBM) in adults in relation to vertebral level and age using dynamic contrast enhancement MRI(DCE-MRI). We found that the quantitative parameters (Ktrans,Kep and Ve )were significantly associated with vertebral level and significantly influenced by age, which could lay a foundation for the further research of vertebral marrow perfusion.

3054.   2 Differences in Two-Compartment Model Parameters of Gluteal and Deep Pelvic Muscles
Milica Medved1, Aytekin Oto1, Xiaobing Fan1, Federico D. Pineda1, Russell Z. Szmulewitz2, and Gregory S. Karczmar1
1Radiology, University of Chicago, Chicago, Illinois, United States, 2Medicine, University of Chicago, Chicago, Illinois, United States

In applications of the two compartment model to tissue contrast agent uptake and washout, it is critical to determine the arterial input function (AIF). The AIF cannot always be measured directly, and approximate methods are sometimes used to derive it. For example, it can be derived by using muscle – with known Ktrans and ve values – as a reference tissue. Published values for skeletal muscle are used, typically measured in an accessible muscle, such as the calf. We show that Ktrans and ve vary between gluteal and deep pelvic muscles, and that thus skeletal muscles should be characterized individually.

3055.   3 Simultaneous Quantification of Permeability and Perfusion in Multiple Sclerosis Lesions
Katherine C. Gao1, Govind Nair1, Colin D. Shea1, Pietro Maggi1,2, Souheil J. Inati3, Luca Massacesi2, and Daniel S. Reich1
1National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, United States, 2Department of Neurological and Psychiatric Sciences, University of Florence, Florence, Italy, 3Natiional Institute of Mental Health, Bethesda, Maryland, United States

Patients with MS typically develop lesions around inflamed blood vessels in the brain. Since permeability and perfusion of MS lesions have been shown to change with time, ascertaining these parameters within individual MS lesions at a particular time point may provide a snapshot of the underlying inflammatory and pathphysiological processes. By acquiring a dual-echo T1-weighted dynamic scan during a single bolus of MRI contrast, we simultaneously estimated permeability and perfusion of chronic and active lesions in MS patients. As expected, enhancing lesions had the highest permeability. Additionally, some chronic lesions had non-zero permeability, which may reflect inflammatory activity that is no longer visibly detectable as enhancement in post-contrast T1-weighted images. Longitudinal studies are underway to track changes in lesion permeability and perfusion over time and will determine whether this methodology can be used to assess the effects of disease-modifying therapies that reduce inflammation and maintain the blood-brain-barrier.

3056.   4 Cerebral Blood Flow Measurement Obtained by PET/MR Dual-Modality Imaging System
Parinaz Massoumzadeh1, Yi Su1, Joshua S. Shimony1, Andrei Vlassenko1, Jonathan McConathy1, and Tammie Benzinger1
1Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, United States

Cerebral blood flow (CBF) has been compared using PET and MR, methods but not using a PET/MR dual-modality imaging system. Here, we compare CBF measurement obtained using three methods: dynamic susceptibility contrast (DSC) MR, Dynamic F18-FDG, and O-15 water PET scans for patients with brain tumor. We use a PET/MR scanner (Siemens Biograph mMR). MR based CBF were found to be correlated with PET CBF at both voxel and regional level, although the correlation was lower than the correlations between [015]PET and FDG imaging. Further investigation is ongoing to investigate the difference between PET and MR based CBF measurements.

3057.   5 Time to Peak Based Differentiation of Functional Placental Compartments in the Mouse Model
Fabian Kording1, Wedegaertner Ulrike1, Nils Daniel Forkert2, Jan Sedlacik1, Gerhard Adam1, and Chressen K. Much1
1Department of Diagnostic and Interventional Radiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, Germany, 2Department of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, Germany

The assessment placental perfusion using dynamic contrast enhanced MRI is of increasing importance for early prediction of fetal growth restrictions and vascular complications during pregnancies. To assess differences in the placenta perfusion in experimental studies analysis is performed as an average over the whole placenta. However, the mouse placenta consists of two different functional zones and differentiating the two compartments may lead to additional important information. In this work placenta functional compartments were successfully differentiated using time-to-peak values of the contrast agent time curve. Perfusion analysis of both compartments revealed significant differences which could be beneficial for further studies.

3058.   6 Measurement of Rat Brain Tumor Kinetics Using an Intravascular Mr Contrast Agent and DCE-T1 Nested Model Selection
Wilson B. Chwang1, Rajan Jain1,2, Siamak P. Nejad-Davarani3,4, A.S.M. Iskander1, Ashley VanSlooten5, Lonni Schultz5, James R. Ewing3,6, Ali S. Arbab1,7, and Hassan Bagher-Ebadian3,6
1Department of Radiology, Henry Ford Hospital, Detroit, MI, United States, 2Department of Neurosurgery, Henry Ford Hospital, Detroit, MI, United States,3Department of Neurology, Henry Ford Hospital, Detroit, MI, United States, 4Department of Biomedical Engineering, University of Michigan, Ann Artbor, MI, United States, 5Department of Public Health Sciences, Henry Ford Hospital, Detroit, MI, United States, 6Department of Physics, Oakland University, Rochester Hills, MI, United States, 7Department of Radiology, Wayne State University, Detroit, MI, United States

The purpose of this study was to investigate parameters of vascular physiology such as vp, Ktrans, and ve in a rat glioma model using two different contrast agents, an intravascular or blood pool agent (gadofosveset) and an extravascular agent (gadopentetate dimeglumine, Gd-DTPA) using DCE T1 nested model selection. We found that Ktrans was significantly lower using gadofosveset compared to Gd-DTPA, while vp and ve measures were not statistically different. But more importantly these parameters were measured with high agreement using DCE T1 NMS, demonstrating the stability of nested model selection in DCE-MRI and its importance for assessing the tumor microenvironment.

3059.   7 Reducing the Scan Time in Quantitative Dynamic Contrast Enhanced MRI of the Breast Using the Extended Graphical Model
Huijun Chen1, Matthew L. Olson2, Savannah C. Partridge3, and William Kerwin3
1Tsinghua University, Beijing, Beijing, China, 2University Of Washington, Seattle, WA, United States, 3University of Washington, Seattle, WA, United States

The Extended Graphical Model (EGM) has the ability to acquire accurate pharmacokinetic parameters (contrast transfer constant: Ktrans) using a shorter scan time than the widely used modified Kety/Tofts model in dynamic contrast enhanced (DCE) MRI of carotid atherosclerotic plaque. However, in the area of oncology, where DCE MRI and pharmacokinetic modeling are widely used in clinical research, the capability of the EGM has not been investigated. In this study, we sought to evaluate the EGM in breast imaging for use with a novel hybrid DCE MRI that provides separate high spatial and high temporal resolution datasets with full bilateral coverage.

3060.   8 Improving the Consistency in Permeability Measurement with DCE-MRI for Longitudinal Follow-Up of Brain Metastatic Tumors
Yi-Ying Wu1, Chen-Hao Wu1,2, Chih-Ming Chiang1, Clayton Chi-Chang Chen1,3, and Jyh-Wen Chai1,4
1Department of Radiology, Taichung Veterans General Hospital, Taichung City, Taiwan (R.O.C), Taiwan, 2Institute of Biomedical Engineering, National Taiwan University, Taipei City, Taiwan(R.O.C.), Taiwan, 3Department of Biomedical Engineering, Hung Kuang University, Taichung City, Taiwan (R.O.C.), Taiwan, 4College of Medicine, China Medical University, Taichung City, Taiwan (R.O.C), Taiwan

Venous output function (VOF) from the larger and straighter superior sagittal sinus, with similar shape of the concentration time curves as AIF, has shown the effectiveness in permeability measurements of brain neoplasms. However, there are still some errors from VOF that may influence the quantification of tissue permeability. The aim of this study is to investigate the clinical applicability of permeability measurement with DCE-MRI, by using a combination of the scaled AIF with VOF and the normalization to the plasma volume of the adjacent white matter, to estimate Ktrans of brain metastatic lesions in the longitudinal follow-up.

3061.   9 Repeatability of Cerebral Perfusion Measurements Using Susceptibility Contrast MRI
Kourosh Jafari-Khouzani1, Kyrre E. Emblem1,2, Jayashree Kalpathy-Cramer1, Atle Bjørnerud2,3, Mark Vangel1, Elizabeth R. Gerstner4, Kathleen M. Schmainda5, Tracy T. Batchelor4, Bruce Rosen1, and Steven M. Stufflebeam1
1Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States, 2The Intervention Centre, Rikshospitalet, Oslo University Hospital, Oslo, Norway, 3Dept of Physics, University of Oslo, Oslo, Norway,4Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, United States, 5Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States

This study evaluates the repeatability of dynamic susceptibility contrast (DSC) based perfusion imaging using a double baseline MRI acquisition setup in 31 adult patients (18 M, 13 F, age 23-72, mean 56) with newly diagnosed glioblastoma. The images were acquired using a dual-echo, combined gradient-echo (GE) and spin-echo (SE) echo planar imaging sequence. Cerebral blood volume (CBV) and cerebral blood flow (CBF) maps were generated and evaluated within tumor regions (enhancing tumor from T1-weighted images and whole tumor including edema from FLAIR image). Repeatability was evaluated using intraclass correlation coefficients. High repeatability was obtained for mean values of perfusion maps within tumor regions.

3062.   10 Variability of CBF Calibration Using Venous Output Function in DSC-MRI of Rat Brains
I Chi Liu1,2, Tsong-Hai Lee3, Ching-Chung Liang4, and Ho-Ling Liu1,5
1Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taoyuan, Taiwan, 2Department of Medical Physics, Koo Foundation Sun Yat-Sen Cancer Center, Taipei City, Taiwan, 3Department of Neurology and Stroke Center, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan, 4Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, and Chang Gung University College of Medicine, Taoyuan, Taiwan, 5Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Taoyuan, Taiwan

Accurate estimation of arterial input function (AIF) is crucial for the CBF quantification using DSC-MRI. In small animals, AIF is difficult to identify due to the inevitable partial-volume effects. This study aimed to investigate the feasibility of using a venous output function (VOF) for calibrating the AIF in rats, and evaluate the deviation caused by the selection of VOF within sagittal sinus. The results showed that using the ratio of areas under the curve from VOF versus AIF after a gamma-variate fitting yielded the most stable CBF calibration. The uncertainties of resulted CBF values were in the range of 8-28%.

3063.   11 A Physiological Model for Injected Contrast Agent Concentration Incorporating Recirculation, Extravasation and Excretion
Dennis Lai Hong Cheong1 and Thian C. Ng1,2
1Clinical Imaging Research Center, SBIC/A*STAR & National University of Singapore, Singapore, Singapore, 2Department of Diagnostic Radiology, National University of Singapore, Singapore, Singapore

In the analysis of DCE MRI, a functional curve representing the arterial or vascular input function is beneficial. Empirical formulations depend on the shape of the input function, and its parameters provide little physiologic meaning. Horsfield physiologically based model is good but its application is limited to human DCE MRI study using Gd-DTPA. We have developed a physiologically based model without this limitation. We demonstrate its ability to fit data measured by both DCE MRI and DCE CT, and at different blood vessel locations. It has potential application to animal studies, and to other measurements (e.g. PET). Unphysiological parameter values may assist in identifying errors in measured input functions, especially in DCE MRI where quantification is problematic.

3064.   12 Automatic AIF Estimation in Multi-Echo DSC-MRI of Pediatric Patients - Avoiding the Noise Floor
Allen T. Newton1,2, Jack T. Skinner1, and Christopher C. Quarles1
1Radiology and Radiological Sciences, Vanderbilt University Institute of Imaging Science, Nashville, TN, United States, 2Radiology and Radiological Sciences, Monroe Carell Jr. Children's Hopsital at Vanderbilt, Nashville, TN, United States

We present a simple method by which investigators performing multi-echo DSC-MRI perfusion studies can identify voxels saturating into the noise floor at later echo times, and show the effect of removing these voxels from analysis on AIF estimation. Furthermore, our study evaluates these methods in a population of pediatric patients, demonstrating their applicability in an actual clinical context.

3065.   13 Alternative Sequence for Arterial Input Function Measurements for Bolus Tracking Perfusion Imaging in the Brain
Elias Kellner1, Irina Mader2, Marco Reisert1, and Valerij G. Kiselev1
1Department of Radiology, University Hospital Freiburg, Freiburg, Germany, 2Section of Neuroradiology, University Hospital Freiburg, Freiburg, Germany

We recently presented a method for a quantitative determination of the arterial input function in the carotid arteries. The AIF-measurement plug-in in the standard DSC perfusion sequence used the apparent shift in the arterial position in one-dimensional projection images and was optimised for high doses of contrast. Here we demonstrate an alternative AIF measurement plug-in for low-dose clinical measurements based on fast two-dimensional readout and the phase AIF. Efficient background suppression using inversion recovery remains a crucial component of the method. We present a comparative discussion of both methods in relation to the dose, tracer type, and the field strength.

3066.   14 High Relaxivity Contrast Reagents Allow Detection of Erythrocyte Transcytolemmal Water Exchange
Gregory J. Wilson1, Charles S. Springer, Jr.2, Mark Woods2,3, Sarah Bastawrous1,4, Puneet Bhargava1,4, and Jeffrey H. Maki1
1Radiology, University of Washington, Seattle, WA, United States, 2Advanced Imaging Research Center, Oregon Health and Science University, Portland, OR, United States, 3Chemistry, Portland State University, Portland, OR, United States, 4Radiology, Puget Sound VAHCS, Seattle, WA, United States

Measurements of longitudinal relaxation rates (R1) of 1H2O in whole blood with gadolinium-based contrast reagent concentrations ([CR]) in the range of 2 to 18 mM provide evidence of water exchange across the erythrocyte cell membrane. The dependence of R1 on [CR] was accurately predicted by the two-site-exchange (2SX) model in the fast exchange regime (FXR). Contrast reagents with high protein binding affinity (gadobenate dimeglumine and gadofosveset trisodium) were more sensitive to the water exchange kinetics because of their higher relaxivities. This sensitivity to water exchange across the cell membrane may enable future studies of erythrocyte function.

3067.   15 Does DCE-MRI Have a Metabolic Dimension?
Martin M. Pike1, Mohan L. Jayatilake1, Xiaoyan Wang2, Merryl R. Lobo1, Xin Li1, Matthias C. Schabel1, William D. Rooney1, Dale J. Christensen3, Jerry D. Glickson4, Rosalie C. Sears2, Wei Huang1, and Charles S. Springer, Jr.1
1Advanced Imaging Research Center, Oregon Health & Science University, Portland, Oregon, United States, 2Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon, United States, 3Oncotide Pharmaceuticals, Research Triangle Park, North Carolina, United States,4Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States

The metabolic dimension of DCE-MRI is explored by using targeted therapy on a genetically modified mouse spontaneous breast cancer. DCE-MRI suggests a metabolic flux decrease upon therapy.

3068.   16 Quantifying Cerebral Haemodynamics Beyond CBF Using Control Point Interpolation Deconvolution for DSC MRI Perfusion Analysis
Amit Mehndiratta1, Bradley J. MacIntosh2, David E. Crane2, Stephen J. Payne1, and Michael A. Chappell1
1Institute of Biomedical Engineering, University of Oxford, Oxford, Oxfordshire, United Kingdom, 2Medical Physics, University of Toronto, Toronto, ON, Canada

Perfusion analysis could provide tissue residue function by deconvolution of the observed MR signal with AIF; however with SVD it is challenging due to non-physiological oscillations. The Control Point Interpolation method has been demonstrated to provide smooth residue functions in perfusion analysis and is sensitive to pathological variations. Our analysis of eight atherosclerotic disease patients showed variation in residue function among healthy and ischemic tissue which was quantified by calculating the time taken for the residue function to drop to 50% and 10% of its maximum value. Capillary transit time heterogeneity information was also extracted from this residue function by calculating transit time distribution for tissue.

3069.   17 DSC-MRI Simulations: What Is the Correct Model for the in vivo Tissue Residue Function?
Amit Mehndiratta1, Fernando Calamante2, Bradley J. MacIntosh3, David E. Crane3, Stephen J. Payne1, and Michael A. Chappell1
1Institute of Biomedical Engineering, University of Oxford, Oxford, Oxfordshire, United Kingdom, 2Melbourne Brain Centre - Austin campus, Brain Research Institute, Heidelberg, Victoria, Australia, 3Medical Physics, University of Toronto, Toronto, ON, Canada

Exponential residue function is commonly used in DSC MRI simulations for cerebral haemodynamic approximation to validate novel deconvolution methodologies. However, the haemodynamics is significantly altered in pathology where exponential approximation might be no more valid. In the study in-vivo observed residue function with non-parametric CPI method were approximated with four commonly used analytical expressions where bi-exponential expression was found to be more realistic approximation of normal and pathological variation in haemodynamics.

3070.   18 CBF Quantification in the Face of Dispersion and Separation of Its Effects from Normal Cerebral Haemodynamics: A Comparison of Deconvolution Methods in DSC-MRI
Amit Mehndiratta1, Fernando Calamante2, Bradley J. MacIntosh3, David E. Crane3, Stephen J. Payne1, and Michael A. Chappell1
1Institute of Biomedical Engineering, University of Oxford, Oxford, Oxfordshire, United Kingdom, 2Melbourne Brain Centre - Austin campus, Brain Research Institute, Heidelberg, Victoria, Australia, 3Medical Physics, University of Toronto, Toronto, ON, Canada

Bolus dispersion is a significant problem in perfusion imaging because of remote AIF measurement. It is challenging to accurately estimate CBF in presence of dispersion; in this study our motivation was to investigate the accuracy in CBF estimate with a number of deconvolution methods, and also investigate the possibility to separate the effects of dispersion from cerebral haemodynamics using these techniques. The ambiguity between true residue function and dispersion could not be resolved with any of the deconvolution methods, but accurate estimates of cerebral perfusion can be achieved with an effectively non-parametric CPI approach even in presence of dispersion.

3071.   19 Analyzing Error Propagation in Semi-Quantitative DCE MRI Parameters in Brain Tumors: A Comparison Study to Monte Carlo Simulation Predictions
Ka-Loh Li1, Xiaoping Zhu1, and Alan Jackson1
1The Wolfson Molecular Imaging Centre, The University of Manchester, Manchester, United Kingdom

Uncertainty analysis for error propagation in five semi-quantitative DCE-MRI parameters was performed. Five patients with NF2 were used for evaluation. Percent deviation (PD) distributions from Monte Carlo simulation were compared with in vivo data. Results: 1) The sum of SE and SErel had greater precision than non-summed metrics for persistent type SI(t); (2) The “normalized” parameters had poorer precision than non-normalized metrics;(3) Rse1/se2 was more accurate for persistent type than washout type; (4) Rse1/se2, showed wide PD distribution. In summary, comparison of in-vivo analysis with Monte Carlo simulation supports the findings of previous studies on synthetic data.

3072.   20 Susceptibility Induced Signal Quenching in DCE-MRI Is Tissue Dependent
Xin Li1, Seymur Gahramanov2, Charles S. Springer, Jr.1, William D. Rooney1, and Edward A. Neuwelt2
1Advanced Imaging Research Center, Oregon Health & Science University, Portland, Oregon, United States, 2Department of Neurology, Oregon Health & Science University, Portland, Oregon, United States

Conventional gradient echo Dynamic-Contrast-Enhanced (DCE) MRI protocols acquire data at short but finite echo time (TE). During contrast reagent (CR) bolus passage, T2* related MRI signal reduction (mainly due to susceptibility gradient introduced by CR) may not be negligible even with short TE, especially at ultra-high field. Using a sequential multi-session DCE-MRI data collection at 11.75 T, we demonstrate that the T2* signal loss in DCE-MRI is tissue dependent and most pronounced for tissues with low CR extravasation which transiently experience large intra-voxel susceptibility gradients.

3073.   21 Random Matrix Theory-Based Noise Reduction for Dynamic Imaging: Application to DCE-MRI
Jeiran Jahani1, Glyn Johnson2, Valerij G. Kiselev3, and Dmitry S. Novikov4
1New York University School of Medicine, New York City, New York, United States, 2University of East Anglia, East Anglia, United Kingdom, 3University Medical Center Freiburg, Freiburg, Germany, 4Radiology, New York Univeristy School of Medicine, New York City, New York, United States

We present a nonlinear algorithm for a simultaneous reduction of noise in a series of dynamic maps, such as those acquired during bolus passage in DCE MRI. Our algorithm utilizes a universal distribution of eigenvalues of a random covariance matrix. Thus we are able to objectively remove the “noisy” eigenvalues and preserve the significant principal components. We test our method in a numerical dynamic phantom to show that the noise-reduction preserves all structural information, and further apply it to DCE MRI. Our method selectively reduces noisy components of the images across time while preserving the informative structures of contrast dynamics.

3074.   22 Determination of Local Tissue Enhancement from Radially Reconstructed Images
Jennifer Moroz1, Piotr Kozlowski2,3, and Stefan A. Reinsberg1
1Physics and Astronomy, UBC, Vancouver, BC, Canada, 2Radiology, UBC, Vancouver, BC, Canada, 3MRI Research Centre, UBC, Vancouver, BC, Canada

A high-temporal resolution arterial input function (AIF) is desired for pharamacokinetic modelling, which may be achieved with a projection-based approach. However, local tissue enhancement will affect the accuracy of the AIF. Tissue enhancement may be visualized from the projections used to estimate the AIF, if acquired radially. This work investigates three methods for radial reconstruction and evaluates their potential for measuring tissue enhancement. An error profile, a plot comparing the profile of the measured enhancement (radial image) with the expected result, was calculated to evaluate the techniques. The NFFT technique had the lowest errors, making it attractive for our application.

3075.   23 Spatial Information Based DCE-MRI Data Reconstruction and Analysis Using PCA
Dattesh D. Shanbhag1, Suresh E. Joel1, Ming-Ching Chang2, Kumar T. Rajamani1, Sandeep Narendra Gupta2, and Rakesh Mullick1
1GE Global Research, Bangalore, Karanataka, India, 2GE Global Research, Niskayuna, NY, United States

In this work, we investigated a block-wise PCA based approach to reconstruct DCE-MRI data. It is based on the hypothesis that there exists overlapping temporal information within a spatial neighborhood which can be exploited to separate noise from true contrast enhancement while maintaining tissue heterogeneity. We demonstrate that PCA based reconstruction of dynamic DCE data produced smooth parametric maps while preserving the lesion conspicuity, compared to pixelated maps produced using voxel-by voxel analysis. This will improve the accuracy of DCE-MRI quantification and enhance the sensitivity of the method in clinical scenario.

24 Magnetic Susceptibility Alterations in Mouse Brains with Prenatal Alcohol Exposure: A Preliminary Study
Wei Cao1, Wei Li1, Shonagh K. O’Leary-Moore2, Kathleen K. Sulik2, G. Allan Johnson3, and Chunlei Liu1,4
1Brain Imaging and Analysis Center, Duke University, Durham, NC, United States, 2Bowles Center for Alcohol Studies,University of North Carolina, Chapel Hill, NC, United States, 3Center for In Vivo Microscopy, Duke University, Durham, NC, United States, 4Department of Radiology, Duke University, Durham, NC, United States

The primary effects of prenatal alcohol exposure are on the brain development and the cognitive and behavioral deficits that ensue. Magnetic susceptibility imaging was used to assess its impact to mouse brains. Two groups of mice (n=3, postnatal day 80) were characterized: an ethanol group and a control group. Two main white matter fiber bundles, anterior commissure and corpus callosum, were analyzed. The orientation dependence of magnetic susceptibility was found significantly decreased in ethanol exposed brains compared to their age-matched controls in both regions. This may be interpreted as a loss of myelination due to prenatal alcohol exposure.


Monday, 22 April 2013 (14:15-15:15) Exhibition Hall
Diffusion Applications

  Computer #  
3077.   25 Progressive Myocardial Sheet Dysfunction from 3 to 16 Months in Duchene Muscular Dystrophy Mice (mdx) Defined by Diffusion Tensor MRI (DTI)
Ya-Jian Cheng1, Junjie Chen2, Shelton D. Caruthers2, and Samuel A. Wickline2
1Biomedical Eng., Washington University In Saint Louis, Saint Louis, Missouri, United States, 2Washington University In Saint Louis, St Louis, MO, United States

Heart muscle, the most important muscle in our body, demonstrates mysterious mechanical function during each heart beat. The heart wall generates up to 50% wall thickening with lower than 15% of fiber shortening. A laminar-like muscle structure, a.k.a. sheets, was found to contribute to such function. Here, we accessed the sheet reorientation function in the most used dystrophy model, mdx mice, with the Langendorff perfused viable hearts and mighty 11.7T diffusion tensor MRI.

3078.   26 Comparison of in vivo and Ex Vivo DTI Cortical Connectivity Measurements in the Squirrel Monkey Brain
Yurui Gao1,2, Ann S. Choe1,2, Xia Li1, Iwona Stepniewska3, and Adam W. Anderson1,2
1Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, United States, 2Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, United States, 3Department of Psychological Sciences, Vanderbilt University, Nashville, Tennessee, United States

In a previous study, we validated DTI-tractography-derived measures of primary motor area (M1) corticocortical (CC) connectivity by comparing the ex vivo DTI connectivity with the histological ground truth. Ex vivo acquisitions typically provide higher image quality than in vivo experiments, since scan times can be much longer and motion is usually not an issue. The goal of the present study was to get a more realistic understanding of the limitations of in vivo DTI measures of CC connectivity by comparing the reliability of in vivo and ex vivo DTI data acquired from the same squirrel monkey.

3079.   27 Preliminary Results on Image Artifacts in Lipid Diffusion Imaging -permission withheld
Jutta Janke1, Andreas Wetscherek1, Bram Stieltjes2, and Frederik B. Laun1,2
1Dpt. Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Baden-Württemberg, Germany, 2Quantitative Imaging-Based Disease Characterization, German Cancer Research Center (DKFZ), Heidelberg, Baden-Württemberg, Germany

The Apparent Diffusion Coefficient (ADC) of lipids may be a valuable biomarker for various diseases, e.g. diabetes. The low ADC of lipids requires the use of long diffusion weightings, which results in low signal-to-noise ratios. Compensating the low SNR by thicker slices lead to unexpected artifacts, which usually do not appear in water diffusion experiments. In particular, we observed pronounced signal drops that we attribute to tissue pulsation and imperfect slice selections due to residual eddy currents. We compensated for these signal drops by using only the maximal signal intensity of all acquired images for the calculation of the ADC.

3080.   28 Diffusion Tensor Imaging of the Mouse Brain with a Cryogenic Coil at Ultrahigh-Field: Fast Imaging Allows for Cohort Studies
Hans-Peter Mueller1, Ina Vernikouskaya2, Albert Ludolph1, Jan Kassubek1, and Volker Rasche2,3
1Department of Neurology, Ulm University, Ulm, Baden Wuerttemberg, Germany, 2Core Facility Small Animal MRI, Ulm University, Ulm, Baden Wuerttemberg, Germany, 3Experimental Cardiovascular Imaging, Ulm University, Ulm, NA, Germany

The SNR gain of cryogenically cooled resonators (CCR)is supposed to generate high fidelity DTI data with high in-plane resolution and thin slices in order to get close to isotropic voxel resolution. That way, accurate fractional anisotropy (FA) mapping and improved isotropic 3D DTI fiber reconstruction could be obtained. The aim of this study is to keep the overall scanning time at approximately 30 minutes in order to enable the application of the scan protocol to in-vivo cohort studies aiming at DTI comparisons of murine brain at the group level.

3081.   29 High Spatial Resolution Diffusion Tensor and Kurtosis Analysis of Formalin Fixed Whole Prostate Tissue
Roger Bourne1, Dominic Pang1, Andre Bongers2, Carl Power2, Paul Sved1, and Geoffrey Watson3
1University of Sydney, Sydney, NSW, Australia, 2University of New South Wales, Sydney, NSW, Australia, 3Royal Prince Alfred Hospital, Sydney, NSW, Australia

This work compares a high spatial resolution diffusion kurtosis analysis of two whole fixed prostates with single b-value DTI of the same voxels. Kurtosis was found to be high in low diffusivity glandular tissue and low in stromal tissue. Variance of the kurtosis correlated strongly with DTI-derived fractional anisotropy.

3082.   30 Manganese Alters Water Movement in Ocular Lens Detected by DTI in vivo
Jennifer Mei1, Hsiao-Fang Liang2, and Shu-Wei Sun2
1University of California, Loma Linda, CA, United States, 2Loma Linda University, Loma Linda, CA, United States

The calcium-dependent aquaporin water channel (AQP) 0 in ocular lens fiber cells facilitates fluid circulation for nourishing the vascular lens to maintain transparency. The goal of this study is to evaluate whether AQP0 malfunction can be detected non-invasively by Diffusion Tensor Imaging (DTI). We used Manganese ions (Mn2+) to alter the AQP0 function in mouse lens. A reduction of radial diffusivity was found in Mn2+-affected lens, compared to the controls.

3083.   31 On the Application of Anomalous Diffusion Metrics in Animal Stroke Models
Farida Grinberg1, Ezequiel Farrher1, Luisa Ciobanu2, and Nadim Jon Shah1,3
1Institute of Neuroscience and Medicine 4 - Medical Imaging Physics, Forschungszentrum Juelich, Juelich, Germany, 2Neurospin, CEA, Gif-sur-Yvette, France,3Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany

We analyse the sensitivity of the stretched- exponential model in providing contrast for ischemic lesions in animal stroke models. Good fits in the extended range of the diffusion weightings were obtained. In frame of the proposed analytical models, the stretched-exponential function is indicative of anomalous diffusion mechanisms and provide complementary means to infer valuable microstructural information. We obtained promising results in terms of image contrast and better understanding of pathological changes in the ischemic lesions.

3084.   32 Preliminary Evidence of Abnormalities in the Prefrontal Cortex of 10 Weeks Old Ts65Dn Mouse Model of Down Syndrome Using DKI-Cerebral Microenvironment Modeling.
Xingju Nie1, Edward S. Hui1, Jens H. Jensen1, Joseph A. Helpern1,2, Ann-Charlotte E. Granholm-Bentley2, Heather A. Boger2, and Maria F. Falangola1,2
1Radiology and Radiological Science, Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, United States, 2Neurosciences, Medical University of South Carolina, Charleston, SC, United States

The goal of this study was to utilize a recently developed cerebral microenvironment modeling (CMM) method to investigate the morphological abnormalities in the prefrontal cortex of young Ts65Dn mice. CMM relates diffusional kurtosis imaging (DKI) data to specific biophysical tissue characteristics. We demonstrated that CMM parameters are sensitive indicators of changes in the complexity of the neurite architecture associated with abnormal brain development and maturation in this model.

3085.   33 Design of a Noninvasive System to Characterize Collagen-Sponge Remodeling Using MRI
Mohammed Salman Shazeeb1,2, Stuart Howes2, Sivakumar Kandasamy2, Christopher H. Sotak1,2, and George Pins2
1Radiology, University of Massachusetts Medical School, Worcester, MA, United States, 2Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, United States

The in vivo evaluation of the remodeling of soft biomaterial implants often involves surgical removal of the implant for subsequent histological assessment. This approach is very resource intensive, it is often destructive, and imposes practical limitations on how effectively these materials can be evaluated. MRI has the potential to non-invasively monitor the remodeling of collagen scaffolds. This study investigated the development of a model system to evaluate the remodeling of implanted collagen scaffolds using MRI and conventional histological techniques. Significant correlations were found between the MRI and histological parameters demonstrating that MRI is sensitive to specific remodeling parameters.

3086.   34 Does Skeletal Muscle Contain Fast and Slow Diffusion Components in High B-Value Diffusion Weighted Imaging (DWI)?
Yoshikazu Okamoto1, Tomonori Isobe1, and Yuji Hirano1
1University of Tsukuba Hospital, Tsukuba, Ibaraki, Japan

How slow and fast diffusion components work in the skeletal muscle?

3087.   35 Accurate Monitoring of the Treatment Response in Whole-Body Bone Marrow Metastatic Cancers Based on ADC Histogram Analysis Employing an Automatic Multiparametric (T1/ADC) Registration/Segmentation Approach
Faezeh Sanaei Nezhad1, Anahita Fathi Kazerooni2,3, Anwar R. Padhani4, Hamid Soltanian Zadeh1, and Hamidreza Saligheh Rad2,3
1School of Electrical and Computer Engineering (ECE), College of Engineering, University of Tehran, Tehran, Iran, 2Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran, 3Quantitative MR Imaging and Spectroscopy Group, Research Center for Cellular and Molecular Imaging, Tehran University of Medical Sciences, Tehran, Iran, 4Paul Strickland Scanner Centre, Mount Vernon Cancer Centre, London, United Kingdom

Bone marrow metastases are common manifestation of many malignant cancers. In order to gain deeper insight into patient’s state of disease and the treatment response, the bone marrow cellularity can be assessed by the histogram analysis and monitoring of the ADC-maps acquired by DW-MRI. However, correct decision making about the effectiveness of therapy is dependent on the ROIs selected from the ADC-maps, raising concerns about the susceptibility of manual ROI placement to human errors. In this work, an automatic bone marrow registration/segmentation histogram analysis approach was applied to the ADC-maps, to show its superiority over the manual ROI analysis method.

3088.   36 Distinct Effects of the Nuclear Volume Fraction and Cell Diameter on Diffusion Contrast in Tumors
Nathan White1 and Anders M. Dale2
1University of California, San Diego, La Jolla, CA, United States, 2Radiology and Neurosciences, University of California, San Diego, La Jolla, CA, United States

The apparent restricted water signal, derived from restriction spectrum imaging (RSI) data, provides improved conspicuity and delineation of high-grade brain tumors and reduced sensitivity to edema compared with traditional ADC. However, the biological origin of the restricted water signal remains poorly understood. In this study, we use Monte Carlo simulations to evaluate the specific role of the nuclear volume fraction and cell diameter on RSI signal contrast. The results suggest that the nuclear volume fraction is an important cellular characteristic for both RSI and ADC contrast, that may explain in part the lack of apparent restriction in low-grade tumors.

3089.   37 Characterization of Diffusion Signal Decay in the Spinal Cord Based on Angular Dispersion of Axons
Novena Rangwala1, David Hackney1, and David C. Alsop1
1Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States

A model of diffusion signal decay in the transverse plane is proposed and applied to high b-value diffusion-weighted (DW) images of the cervical spinal cord (SC) in vivo. This model assumes that axons within SC are not perfectly aligned and the transverse signal decay is a function of the angle made by the axons with the cord axis. The results show that the average axonal dispersion in the cord is ~10°, and decreases to ~6.5° within the posterior funiculus of white matter, indicating that the model is sensitive to regional differences in axon structure.

3090.   38 Comparison of Conventional Histology and Diffusion Weighted Microimaging for Estimation of Epithelial, Stromal, and Acinar Volumes in Prostate Tissue
Michael Zhao1, Esther Myint2, Geoffrey Watson3, and Roger Bourne1
1University of Sydney, Sydney, NSW, Australia, 2Laverty Pathology, Sydney, NSW, Australia, 3Royal Prince Alfred Hospital, Sydney, NSW, Australia

Diffusion weighted microimaging of fixed prostate tissue reveals distinct diffusivity differences between epithelium, stroma, and acinal spaces1. In normal glandular tissue changes in the relative volumes of epithelium and stroma explain ~60% of the variation in signal fraction of a biexponential model of diffusion signal decay. We hypothesise that microscopic tissue volume changes may also explain the observed strong correlation between cancer Gleason grade and apparent diffusion coefficient measured in vivo. In this pilot study we used semi-automated morphometry methods to quantify partial volumes of epithelium, stroma and acinal space in H&E-stained histological images of benign and cancerous prostate tissue and compared these results with segmentation and statistical analysis of diffusion weighted microimages of normal tissue.

3091.   39 Diagnostic Accuracy of Periodically Rotated Overlapping Parallel Lines with Enhanced Reconstruction (PROPELLER) Diffusion-Weighted MRI in Cholesteatomas -permission withheld
Yu-Chun Lin1, Jiun-jie Wang2, Che-Ming Wu3, and Shu-Hang Ng1
1Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, 333, Taiwan, 2Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taoyuan, 333, Taiwan, 3Department of Otolaryngology, Chang Gung Memorial Hospital, Linkou, Taiwan, Taiwan

The study evaluated the diagnostic value of multishot fast spin-echo periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) diffusion weighted imaging (DWI) in detecting cholesteatoma. The surgical pathologic findings were used as the reference standard in 23 patients. The images using PROPELLER DWI had significantly lower susceptibility and geometric artifacts, which resulted in higher sensitivity and accuracy compared with those using the single-shot EPI DWI. Both two techniques had 100% specificity in diagnosis. The multishot fast spin-echo PROPELLER DWI provided better diagnostic utility in detecting middle ear cholesteatoma compared with conventional EPI-DWI.

3092.   40 Diffusion Weighted Magnetic Resonance Imaging of the Breast: Technical Considerations and Clinical Applications
Habib Rahbar1,2, Matthew L. Olson1,2, Constance D. Lehman1,2, and Savannah C. Partridge1,2
1Radiology, University of Washington, Seattle, WA, United States, 2Radiology, Seattle Cancer Care Alliance, Seattle, WA, United States

Diffusion weighted (DW) breast MR holds promise as an adjunct technique to standard dynamic contrast-enhanced breast MR, a biomarker of disease subtypes, and a non-contrast screening tool. In this educational exhibit, we review the technical considerations and current evidence for clinical applications of this promising MR technique. We also highlight areas requiring further research to allow widespread implementation of this technique into clinical breast MR protocols.

3093.   41 in vivo Measurement of Axonal Diameter and Density of Human Corpus Callosum Using Bi-Gaussian Model Q-Planar MRI
Jun-Cheng Weng1,2, Sih-Yu Lin1, and Wen-Yih Isaac Tseng3,4
1School of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung, Taiwan, 2Department of Medical Imaging, Chung Shan Medical University Hospital, Taichung, Taiwan, 3Center for Optoelectronic Biomedicine, National Taiwan University College of Medicine, Taipei, Taiwan, 4Department of Medical Imaging, National Taiwan University Hospital, Taipei, Taiwan

It is known that water signal decay in a MR diffusion experiment in neuronal tissues, at sufficiently high diffusion weighting, appears to be non-mono-exponential, thus complicating even further the interpretation and assignment of the different components to actual physiological compartments. Therefore, we used 2D bi-Gaussian model (i.e. slow and fast components) to fit our QPI data. After 2D Fourier transformation of the slow and fast Gaussian curved surfaces of signal decay, respectively, two Gaussian curved surfaces of displacement distribution (i.e. narrow and broad components) were obtained. Intracellular and extracellular information could then be extracted from the narrow and broad Gaussian displacement distributions, respectively. Our results demonstrated that bi-Gaussian fitting QPI produced reasonable distribution of relative axonal diameters of CC in normal human brain.

3094.   42 Comparison of the ADC Measurement in Liver DWI with Multi-Breath-Hold, Free Breathing, Respiratory Triggered and Navigator Triggered Techniques
Zaiyi Liu1, Changhong Liang1, and Xin Chen1
1Dept. of radiology, Guangdong General Hospital, Guangzhou, Guangdong, China

ADC is a promising imaging biomarker for characterizing liver lesions and predicting and monitoring the response of hepatic diseases to treatment. However, there's a wide variety in liver ADC values which have been reported, even in normal liver. Knowledge of the characteristic of ADC measurement in normal liver is of great importance for accurate interpretation of ADC changes. Our results showed that the ADC values are influeced by both DWI techniques and anatomical location of the liver, thus we should use the same technique and the same location when evaluate the ADC values changes in diffuse liver disease after treatment.

3095.   43 Hormonal Contraceptives Dependency of Quantitative Diffusion Kurtosis Parameters in the Limbic System: A Voxel Based Approach
Timo De Bondt1, Wim Van Hecke2, Jelle Veraart3, Alexander Leemans4, Jan Sijbers3, Stefan Sunaert5, Yves Jacquemyn6, and Paul M. Parizel1,7
1Radiology, Antwerp University Hospital, Antwerp, Antwerp, Belgium, 2icoMetrix, Leuven, Belgium, 3Physics, University of Antwerp, Antwerp, Antwerp, Belgium,4Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands, 5Radiology, University Hospitals of the Catholic University Leuven, Leuven, Belgium, 6Gynaecology and Obstaetrics, Antwerp University Hospital, Antwerp, Antwerp, Belgium, 7Radiology, University of Antwerp, Antwerp, Antwerp, Belgium
3096.   44 Semiautomatic Segmentation and Quantification of Volume, T2 Relaxation Time and Mean Diffusivity of the Human Brain CSF Compartments Across the Lifespan
Khader M. Hasan1 and Ponnada A. Narayana1
1Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, Houston, Texas, United States

Due to its close interplay with the vasculature, cerebrospinal fluid (CSF) serves as a chemical conduit in intracranial pressure regulation and chemical function. Whole brain, sulcal and ventricular CSF volumes have been used as a marker of normal brain development and aging and atrophy in a host of pathologies, including closed traumatic brain injuries. In addition CSF chemical and metabolic content serves as a robust biomarker of neural degeneration. A comprehensive analysis of normative CSF compartmental volumetry, relaxometry and diffusimetry has not been described previously using quantitative magnetic resonance imaging (qMRI). In this report, we applied novel and validated atlas-based segmentation methods for a detailed investigation of age dependent qMRI changes in the CSF compartments in both men and women

3097.   45 Cerebrospinal Fluid Flow Detection on Diffusion-Weighted Reversed Fast Imaging with Steady-State Precession -permission withheld
Tetsu Niwa1, Koki Kusagiri2, Noriko Aida2, Taro Takahara3, Tomoaki Nagaoka4, and Yutaka Imai1
1Radiology, Tokai University School of Medicine, Isehara, Kanagawa, Japan, 2Radiology, Kanagawa Children's Medical Center, Yokohama, Kanagawa, Japan,3Biomedical Engineering, Tokai University School of Engineering, Isehara, Kanagawa, Japan, 4Electromagnetic Compatibility Laboratory, Applied Electromagnetic Research Institute, National Institute of Information and Communications Technology, Koganei, Tokyo, Japan

We assessed whether diffusion-weighted reversed fast imaging with steady-state precession (DW-PSIF) can demonstrate cerebrospinal fluid flow. DW-PSIF showed signal reduction at the cerebrospinal fluid (CSF), which was corresponded to CSF flow on phase-contrast imaging. DW-PSIF with higher moment revealed less imaging quality and less signal-to-noise ratio. DW-PSIF can be a method to assess CSF flow in a relatively good imaging quality and in a short time.

3098.   46 in-vivo Diffusion Tensor Imaging of the Systemic Right Ventricle at 3T
Jack Harmer1, Nicolas Toussaint1, Kuberan Pushparajah1, Christian T. Stoeck2, Rachel W. Chan3, Reza Razavi1, David Atkinson3, and Sebastian Kozerke1,2
1Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, United Kingdom, 2Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, 3Centre for Medical Imaging, University College London, London, United Kingdom

Advances in diffusion acquisition schemes employing stimulated echoes now allow for robust DTI of the beating heart. When used in conjunction with respiratory navigation, data can be acquired during free breathing making it potentially feasible in patients. We demonstrate how in-vivo DTI data can be acquired in a patient with a systemic right ventricle, allowing novel insights into the adaptation of myofibre architecture in a morphological right ventricle supporting systemic circulation. This is to our knowledge the first record of in-vivo DTI of a systemic right ventricle. The technique has considerable potential for furthering our understanding of congenital heart disease.

3099.   47 Diffusion Behaviour of Water and Fat in Bone Marrow
Valentina Di Marco1, Marco Palombo1,2, and Silvia Capuani1,2
1Physics Department, Sapienza University, Rome, Rome, Italy, 2CNR IPCF UOS Roma, Physics Department, Sapienza University, Rome, Rome, Italy

We investigated the potential of Gaussian and non-Gaussian diffusion methods to obtain information about the microstructural complexity and the water compartmentalization in free and trabecular bone-marrow by investigating apparent diffusion coefficient (ADC) of the water and the fat component as a function of diffusion time (Capital Greek Delta). ADCs of the fat were found to be constant as a function of Capital Greek Delta, while the intracellular and the extracellular water exhibits a different ADC behavior as a function of Capital Greek Delta in free and trabecular bone marrow. Internal gradient at the interface between water and bone affects extracellular ADC behaviour which is non-Gaussian.

3100.   48 Quantitative and Qualitative Analysis of Diffusion Tensor Imaging of the Median Nerve Region at the Carpal Tunnel in Various Clinical Settings -permission withheld
Eiko Yamabe1, Ryo Miyagi2, Toshinori Sakai3, Toshiyasu Nakamura4, and Hiroshi Yoshioka1
1Department of Radiological Sciences, University of California Irvine, Orange, CA, United States, 2Department of Orthopaedic Surgery, Miyoshi City National Insurance Nishi-Iya Clinic, Tokushima, Japan, 3Department of Orthopedics, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan, 4Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan

We qualitatively visualized the median nerve with diffusion tensor imaging in various acquisition positions/parameters and quantitatively investigated changes in diffusion values (FA, ADC) of the median nerve at different locations of the carpal tunnel in healthy volunteers. The median nerve at the carpal tunnel including a small nerve fiber such as a motor branch was well appreciated on fiber tracking images. Comparable fiber tracking images and FA/ADC values were obtained in supine and prone positions without any statistical differences. These results show a potential for their clinical use.


Monday, 22 April 2013 (15:15-16:15) Exhibition Hall
Diffusion to Measure Perfusion

  Computer #  
3101.   25 Perfusion Measurement of Brain Tumors:Comparison Between IVIM and DSC
Qunfeng Tang1, Hongwei Chen1, and Hui Liu2
1Radiology, Wuxi People Hospital, Nanjing Medical University, Wuxi, Jiangsu, China, 2MR Collaboration NE Asia, Siemens Healthcare, Shanghai, Shanghai, China

In the brain application, IVIM is a method capabling of simultaneously measuring CBF, CFV and ADC. In this study, we evaluated this IVIM based perfusion by comparing with the traditional DSC based perfusion measurement in 3 types of tumors. Initial results shows the consistent in CBF measurement between IVIM and DSC based methods except 18% cases which are considered to be contributed by flow effect for IVIM measurement.

3102.   26 Imaging Parameters of High Grade Gliomas in Relation to the MGMT Promoter Methylation Status: Diffusion Tensor Imaging, Perfusion Imaging and Intravoxel Incoherent Motion Imaging Using 3.0-T MR
Tao Jiang1, Peng Wang1, Shi-Yuan Liu1, Weibo Chen2, and Queenie Chan3
1Department of Radiology, Shanghai Changzheng Hospital, Shanghai, China, 2Philips Healthcare, Shanghai, China, 3Philips Healthcare, Hong Kong, China

This study mainly focus on whether the the methyl-guanine methyl transferase(MGMT) promoter methylation status is associated with a specific imaging feature and several imaging parameters (ADC, FA and perfusion parameters) of HGGs.

27 Potential of Perfusion and Diffusion IVIM MRI in a Rat Brain 9L Glioma Model -permission withheld
Mami Iima1,2, Olivier Reynaud1, Tomokazu Tsurugizawa1, Luisa Ciobanu1, Jing-Rebecca Li1, Françoise Geffroy1, Boucif Djemai1, Masaki Umehana3, and Denis Le Bihan1
1Neurospin, CEA Saclay, Gif-sur-Yvette, Ile-de-France, France, 2Diagnostic Imaging and Nuclear Medicine, Kyoto University Graduate School of Medicine, Kyoto, Kyoto, Japan, 3Kyoto University Faculty of Medicine, Kyoto, Kyoto, Japan

IVIM MRI images were acquired in 14 rats implanted with a 9L glioma model using a 17.2T MRI scanner. IVIM maps clearly highlighted areas with high and low fraction perfusion within tumors which were generally heterogeneous, as confirmed by histology. Perfusion parameters could easily be obtained using a 2-steps processing approach. Diffusion parameters obtained using a biexponential 2-compartments diffusion model, such as ADCo and fslow, additionally provided information in tissue structure. However, the diffusion parameters estimated from the biexponential model were found to be very sensitive to noise and to the initial values used for data fitting.

3104.   28 Optical Model Mapping for Characterizing Tumor Microcirculation with Diffusion Weighted Imaging in Head and Neck Cancer
Yonggang Lu1, Jacobus F.A. Jansen2, Yousef Mazaheri1, Hilda E. Stambuk3, and Amita Shukla-Dave1
1Medical Physics Department, Memorial Sloan-kettering Cancer Center, New York, NY, United States, 2Radiology Department, Maastricht University, Maastricht, Maastricht, Netherlands, 3Radiology Department, Memorial Sloan-kettering Cancer Center, New York, NY, United States

This study proposes optimal model mapping to characterize tumor microcirculation with diffusion weighted imaging in head and neck cancer. At each voxel within tumor tissue, an optimal model was determined to quantify tumor microcirculation from several common diffusion models based on the Bayesian Information Criterion. For individual tumors, voxel percentage for each model and the optimal model map were generated. The results were promising in characterizing the heterogeneity of tumor microcirculation. Future studies with large cohort of patients need to assess the use of this method in clinical applications such as tumor diagnosis, staging and treatment monitoring.

3105.   29 Intravoxel Incoherent Motion MR Imaging and Dynamic Contrast-Enhanced MRI in Brain Tumors: Correlation of Quantitative and Semi-Quantitative Parameters
Moritz Jörg Schneider1, Michael Ingrisch1, Birgit Ertl-Wagner2, Maximilian F. Reiser2, and Olaf Dietrich1
1Josef Lissner Laboratory for Biomedical Imaging, Institute for Clinical Radiology, LMU Ludwig Maximilian University of Munich, Munich, Bavaria, Germany,2Institute for Clinical Radiology, LMU Ludwig Maximilian University of Munich, Munich, Bavaria, Germany

Intravoxel incoherent motion (IVIM) MRI can be used to obtain information about tissue microcapillary perfusion properties based on diffusion-weighted acquisitions. Therefore, we compare perfusion-related parameters obtained by IVIM measurements with cerebral blood volume and flow (CBV,CBF) as well as semi-quantitative parameters retrieved from dynamic-contrast-enhanced (DCE) MRI in tumorous and normal-appearing white matter. The IVIM perfusion fraction f correlates well with CBV and CBF, indicating that IVIM yields perfusion-related information. All of the DCE parameters correlate strongly with the product D*×f, which reflects a “makeshift flow”and is therefore likely to be the best indicator for tissue-perfusion changes.

3106.   30 Investigating the Effect of Intra-Voxel Contrast Agent Diffusion on Quantitative DCE-MRI
Stephanie L. Barnes1,2, Christopher C. Quarles1,2, and Thomas E. Yankeelov1,2
1Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States, 2Vanderbilt University Institute of Imaging Sciences, Vanderbilt University, Nashville, TN, United States

Quantitative DCE-MRI analysis does not account for diffusion of the contrast agent (CA) within a voxel. This work utilizes a finite element model of CA diffusion to investigate the effect of diffusion on intra-voxel CA distribution, and the resulting effect on voxel SI and parameterization error. The results show that decreasing homogeneity of CA distribution increase the difference in effective total voxel signal intensity (SI). Additionally, CA diffusion (over a range of relevant values) affects SI on a time scale on the order of common temporal resolutions. These results demonstrate the potential importance of CA diffusion in DCE-MRI analysis.

3107.   31 Pulsatile Microvascular Perfusion Demonstrated in the Human Brain with Intravoxel Incoherent Motion (IVIM) MRI
Christian Federau1, Kieran O'Brien2, Markus Müller3, Matthias Stuber1,4, Reto Meuli1, Philippe Maeder1, and Patric Hagmann1
1Radiology, CHUV, Lausanne, VD, Switzerland, 2CIBM, Université de Genève, Lausanne, VD, Switzerland, 3The Abdus Salam International Center for Theoretical Physics, Trieste, Trieste, Italy, 4CIBM, Lausanne, VD, Switzerland

We present evidence that the IVIM perfusion parameters (f, the perfusion fraction, D*, the pseudo-diffusion coefficient, and fD*, which is related to blood flow) depend on the cardiac cycle in the human brain, while the diffusion coefficient was found to be stable. This represents direct experimental evidence of pulsatile flow in the human brain microvasculature and correlates well with recently reported measurement of pulsatile blood flow in the microvasculature of the cortex of the mice brain by Santisakultarm et al (Am J Physiol Heart Circ Physiol, 2012) using two-photon microscopy.

3108.   32 Different Kinetics of Post-Exercise Perfusion Fraction by Diffusion-Weighted Imaging Between Athletes and Non-Athletes
Yoshikazu Okamoto1, Graham J. Kemp2, and Tomonori Isobe1
1University of Tsukuba Hospital, Tsukuba, Ibaraki, Japan, 2University of Liverpool, Liverpool, Liverpool, United Kingdom

New measurement method of skeletal mucle perfusion by IVIM

3109.   33 IVIM with Simultaneous T2 Mapping and Relaxivity Correction
Sangwoo Lee1, Jeong Min Lee2, Jeong Hee Yoon2, and Hiroyuki Kabasawa3
1Global Applied Science Lab, GE Healhcare, Gangnam-gu, Seoul, Korea, 2Radiology, Seoul National University Hospital, Jongno-gu, Seoul, Korea, 3Global Applied Science Laboratory, GE Healhcare, Hino-shi, Tokyo, Japan

IVIM (IntraVoxel Incoherent Motion) has been widely used in various clinical applications including liver fibrosis staging and hepatic tumor characterization. However, in those studies, there has been no consideration of T1 and T2 relaxation differences between blood and tissue within the IVIM signal model. It was reported that perfusion fraction can be significantly affected by imaging TE due to such relaxation differences. In this work, we demonstrated the feasibility of simultaneous estimation of tissue T2 map within single IVIM data acquisition and compensation of perfusion fraction using the acquired T2 map.

3110.   34 Insight Into Intravoxel Incoherent Motion: Appearance of Signal from Interstitial Fluid
Kimihiro Ogisu1, Akiko Fujita2, and Toru Yamamoto3
1Department of Radiology, National Hospital Organization Hokkaido Medical Center, Sapporo, Hokkaido, Japan, 2Graduate School of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan, 3Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, Japan

Blood flow in capillaries has been believed to be intravoxel incoherent motion whose MR signal appears in diffusion weighted imaging at low b values as well as MR signal from free water. However, we found an increase in T2 with decreasing b values, and this increase cannot be interpreted by blood in capillaries. MR signal from interstitial fluid (ISF), the T2 of which is around 300 ms, agrees the T2 increase. Blood flow in capillaries is rather understood as intravoxel coherent motion by using anisotropic directional distribution model of vessel segments.

3111.   35 Compressed Sensing for Flow-Compensated Intra-Voxel Incoherent Motion Modeling
Andreas Wetscherek1,2, Frederik B. Laun1,3, Claudia Prieto2,4, and Cristián Tejos2,5
1Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Biomedical Imaging Center, Pontificia Universidad Catolica de Chile, Santiago, Chile, 3Quantitative Imaging-Based Disease Characterization, German Cancer Research Center (DKFZ), Heidelberg, Germany, 4Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom, 5Department of Electrical Engineering, Pontificia Universidad Catolica de Chile, Santiago, Chile

The flow-compensated (FC) intra-voxel incoherent motion (IVIM) model allows probing the characteristic timescale and velocity of the incoherent motion using FC diffusion weighted MRI. To reduce the long acquisition times required, we applied a compressed sensing reconstruction exploiting sparsity of the Karhunen-Loève transform domain to a 3x undersampled data set. We were able to show that the CS reconstruction improved the accuracy of the parameter maps obtained from the undersampled data making their quality comparable to those obtained from non-undersampled data.

3112.   36 Lenaldekar Prevented Relapses in Experimental Autoimmune Encephalomyelitis Mice: A Diffusion Basis Spectrum Imaging Study
Xiaojie Wang1, Matthew Cusick2, Robert S. Fujinami2, and Sheng-Kwei Song3,4
1Chemistry, Washington University, St. Louis, MO, United States, 2Pathology, University of Utah, Salt Lake City, UT, United States, 3Radiology, Washington University, St. Louis, MO, United States, 4Hope Center for Neurological Disorders, Washington University, St. Louis, MO, United States

SJL-EAE mice were treated with LDK or vehicle from the onset of first relapse to the study end-point (37 day post immunization). 99-direction DBSI was performed to examine the spinal cord white matter pathology. Axon and myelin integrity of the spinal cord white matter was assessed using axial and radial diffusivity, respectively, while inflammation extent was evaluated using cell ratio and edema water ratio derived by DBSI. LDK diminished the disease activity through the anti-inflammatory, axon preservation and probably remyelination effect.

3113.   37 Comparing of Mono-Exponential, Bi-Exponential and Stretched Exponential Models with Multi-B Value Diffusion Weighed Imaging in Uterus Malignancies¡ªpilot Study -permission withheld
Yan Zhou1, Jianyu Liu2, He Wang3, and Nan Sun4
1Peking University Third Hospital, Beijing, Beijing, China, 2Radiology Department, Peking University Third Hospital, Beijing, Beijing, China, 3MR Research China, GE Healthcare, Shanghai, Shanghai, China, 4MR Research China, GE Healthcare, Beijing, Beijing, China

In this study, multi-b value Diffusion Weighed imaging models of mono-exponential, bi-exponential (intravoxel incoherent motion, IVIM) and stretched exponential models were discussed in diagnosing endometrial cancer and cervix cancer, in order to find more reliable or more precise method to deal with DWI. The results showed good diagnostic value of Slow ADC in IVIM model, and showed potentially ability of using perfusion fraction as a non invasive method assessing perfusion. While stretched exponential model were questioned by some results from this study.

3114.   38 Development of a Phantom for Quality Assurance in Multi-Centre Clinical Trials with Diffusion-Weighted MRI
Naomi H. M. Douglas1, Jessica M. Winfield1, Nandita M. deSouza1, David John Collins1, and Matthew R. Orton1
1Radiotherapy and Imaging, Institute of Cancer Research, Sutton, Surrey, United Kingdom

A phantom suitable for quality assurance in multi-centre clinical trials has been designed and built. Phantom development involved testing of: temperature stability; relaxivity dependence on concentrations of sucrose and manganese chloride; ADC dependence on concentrations of sucrose and manganese chloride. Sodium azide was added to each of the solutions as a bactericidal agent. The final phantom is of a modular design containing samples with physiologically relevant values of ADC, T1 and T2. This test object is being used to aid the validation of ADC as a biomarker for treatment response of tumours in multi-centre clinical trials.

3115.   39 UMMDiffusion: An OsiriX Plug-In for ADC and IVIM Analysis in Clinical Routine
Frank G. Zöllner1, Sven Kaiser1, Gerald Weisser2, and Lothar R. Schad1
1Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Baden-Württemberg, Germany, 2Institute for Clinical Radiology and Nuclear Medicine, Medical University Center, Heidelberg University, Mannheim, Baden-Württemberg, Germany

Intra-voxel incoherent motion (IVIM) diffusion weighted imaging (DWI) is an emerging method to derive microscopic structural information non-invasively [1]. To allow for a broader usage, in this work, an OsiriX plug-in was developed to submit the DWI analysis and specific the IVIM model for integration in the clinical routine diagnostics.Based on 30 data sets of prostate, a t-test revealed, that there was no significant difference (p < 0.05) between the plugin and a reference implmentation.

3116.   40 Does the Protein Content Influence on DWI-Thermometry?: Artificial CSF Phantom Study -permission withheld
Koji Sakai1, Ryusuke Nakai1, Kei Yamada2, Jun Tazoe2, Kentaro Akazawa2, and Naozo Sugimoto1
1Kyoto University, Kyoto, Kyoto, Japan, 2Kyoto Prefectural University of Medicine, Kyoto, Kyoto, Japan

Among these MR methods, the most clinically applicable may be the post processing of diffusion-weighted images (DWI). However, this DWI-based method might be influenced by the composition of the CSF, which can strongly affect its viscosity and diffusivity. The purpose of this study was to investigate the influence of protein content on DWI thermometry by using artificial CSF (ACSF) with variable protein concentrations. The protein content of ACSF increased viscosity and decreased the diffusion coefficient. Consequently, the results of DWI thermometry were influenced by the protein content in the range of 0.10 to 1.11 mg/ml (0.10 ºC – 0.42ºC).

3117.   41 Measurement of Portal Venous Flow Using Phase-Contrast MRI at 9.4T: Preliminary Repeatability, Reproducibility and Invasive Validation Studies
Manil Chouhan1,2, Alan Bainbridge3, Nathan Davies4, Rajiv Jalan4, Rajeshwar Mookerjee4, Simon Walker-Samuel2, Mark F. Lythgoe2, Shonit Punwani1, and Stuart Taylor1
1UCL Centre for Medical Imaging, University College London, London, London, United Kingdom, 2UCL Centre for Advanced Biomedical Imaging, University College London, London, London, United Kingdom, 3Department of Medical Physics, University College Hospitals NHS Trust, London, London, United Kingdom, 4UCL Institute for Liver and Digestive Health, University College London, London, London, United Kingdom

The lack of robust non-invasive techniques for repeated measurement of liver blood flow has restricted understanding of the vascular changes underpinning chronic liver disease and the development of therapies to address these changes. Phase-contrast MRI has potential for portal venous flow quantification and in this study we demonstrate repeatability of phase-contrast MRI and present encouraging initial data demonstrating reproducibility of measurements and validation of flow quantification against invasive transit-time ultrasound measurements.

3118.   42 Validation of Cerebral Blood Volume Quantification in Humans by Rapid Steady State T1 MRI
Teodora-Adriana Perles-Barbacaru1, Irène Troprès1, David Chechin2, Sylvie Grand1, Jean-François Le Bas1, Francois Berger1, and Hana Lahrech1
1Grenoble Institute of Neurosciences, University of Joseph Fourier, INSERM U 836, La Tronche, France, 2Philips Healthcare, Suresnes, France

The Rapid Steady State T1 technique enables direct quantitative mapping of the cerebral blood volume fraction with a clinically approved Gd-DOTA dose during the first pass and without requirement of the arterial input function. It facilitates treatment monitoring and clinical studies in particular for the evaluation of antiangiogenic therapies.

3119.   43 Quantification of Pulmonary Perfusion Using Fourier Decomposition Method
Åsmund Kjørstad1, Dominique M.R. Corteville1, André Fischer2, Frank G. Zöllner1, and Lothar R. Schad1
1CKM, Heidelberg University, Mannheim, Baden-Württemberg, Germany, 2Institute of Radiology, University of Wuerzburg, Würzburg, Bavaria, Germany

The Fourier Decomposition method is established as a non-invasive method for perfusion related information in the lung, and has shown promise in clinical studies. One drawback is the lack of meaningful quantification, making follow-up and comparison of patients difficult. We show that quantification of Fourier Decomposition maps is both possible and easy, requiring only a small amount of post-processing.

3120.   44 D2O Perfusion MRI: Investigation on the D2O Infusion Method
Chin-Tien Lu1, Tzu-Chen Yeh2, and Fu-Nien Wang1
1Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan, 2Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan

D2O can be used as a free diffusible tracer for measurement of tissue perfusion. Recently, an indirect strategy for D2O perfusion MRI was proposed by monitoring the 1H signal attenuation. In this study, we aimed to further utilize the characteristic of long time course of D2O. Using syringe pump for stable infusion of 2ml/100g D2O and proton-density weighted RARE for dynamic imaging, intact brain morphology and good perfusion contrast were achieved in location with severe susceptibility effect.

3121.   45 Numerical Approach for Quantitative BOLD with Vessel Size Estimate – Validation on Phantom.
Nicolas Pannetier1,2, Maja Sohlin3, Thomas Christen4, Lothar R. Schad5, and Norbert Schuff1,2
1Department of Radiology, University of California San Francisco, San Francisco, CA, United States, 2Centre for Imaging of Neurodegenerative Diseases, Veteran Affairs Medical Centre, San Francisco, CA, United States, 3MR centre, Sahlgrenska University Hospital, Goteborg, Goteborg, Sweden, 4Department of Radiology, Stanford University, Stanford, CA, United States, 5Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Heidelberg, Germany

MRI is a powerful tool to investigate the microvasculature. Various techniques benefit from the entanglement of the contrasts that arise within a voxel and provide relevant biomarkers. However, the analysis relies on analytical models that present a discrepancy with Monte Carlo simulations. In this work we present a versatile approach directly based on a numerical model. The approach is evaluated on phantom data where vessels are mimicked by polyamide strings. We compared our model with analytical ones and we demonstrated that this approach could provide a mean to estimate the radius of the vessel without the use of contrast agent (CA).

46 Quantitative BOLD Analysis Using a Numerical Model. Blood Volume, Oxygenation and Vessel Size Measurement in the Rat Brain.
Nicolas Pannetier1,2, Benjamin Lemasson3,4, Thomas Christen5, Greg Zaharchuck5, Emmanuel Luc Barbier3,4, and Norbert Schuff1,2
1Department of Radiology, University of California San Francisco, San Francisco, CA, United States, 2Centre for Imaging of Neurodegenerative Diseases, Veteran Affairs Medical Centre, San Francisco, CA, United States, 3Grenoble Institute of Neurosciences, Grenoble University, La Tronche, Rhone-Alpes, France, 4U836, INSERM, La Tronche, Rhone-Alpes, France, 5Department of Radiology, Stanford University, Stanford, CA, United States

The analytical description of the susceptibility-related MR dephasing is used to assess the microvasculature. However, analytical solutions are discordant with Monte Carlo simulations and this discrepancy lead to bias vascular estimates. Moreover recent results demonstrate that BVf and SO2 cannot be assessed at once in qBOLD. In this work, we proposed a new integrative approach to simultaneously assess blood volume, oxygenation and the radius of the vessel. We built up a densely sampled lookup table by simulating the MR signal provided by a Gradient Echo Sampling of the FID and SE sequence prior and post injection of a contrast agent. We acquired the corresponding sequence on rats with focal brain ischemia and we estimated the vascular parameters from the LT.

3123.   47 Does T2' Depend on the Measurement Method? Considerations for Quantitative BOLD Oxygenation
Wendy W. Ni1,2, Thomas Christen1, Zungho Zun1, and Greg Zaharchuk1
1Department of Radiology, Stanford University, Stanford, CA, United States, 2Department of Electrical Engineering, Stanford University, Stanford, CA, United States

In this study, we compare the measurement of reversible contribution R2'=1/T2' of the transverse relaxation rate using nine methods characterized by three approaches: asymmetric spin echo (ASE), Gradient-Echo Sampling of FID and Echo (GESFIDE), and combined (COMBO). We found that the mean value, spatial SNR and inter-subject variation of resulting R2' maps differed significantly between methods, highlighting the importance of making a careful choice in R2' measurement method for quantitative BOLD (qBOLD) oxygenation measurements.


Monday, 22 April 2013 (14:15-15:15) Exhibition Hall
Diffusion: Models & Microstructure

  Computer #  
3124.   49 Complex Patterns of Non-Gaussian Diffusion in Artificial Anisotropic Tissue Models
Farida Grinberg1, Ezequiel Farrher1, Ivan I. Maximov1, and Nadim Jon Shah1,2
1Institute of Neuroscience and Medicine, Forschungszentrum Juelich, Juelich, Germany, 2Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany

We report on the results of the application of several non-Gaussian (diffusion kurtosis, log-normal distribution function, stretched exponential function) and anomalous diffusion models to describe experimental data in the anisotropic fibre phantoms. We focus on the influence of fibre packing density on the quantitative metrics of these models and compare their sensitivity to this parameter. We examine the power-law dependences of the apparent diffusivity on time and fibre density in the frame of anomalous diffusion model.

3125.   50 Classification of Axon Diameter Properties Using Machine Learning
Shlomi Lifshits1, Assaf Horowits2, Daniel Barazany2, Saharon Rosset1, and Yaniv Assaf2
1Department of Statistics and Operations Research, Tel-Aviv University, Tel-Aviv, Israel, 2Department of Neurobiology, Tel-Aviv University, Tel-Aviv, Israel

We suggest formulating the AxCaliber framework as a statistical learning classification problem and show that biologically consistent results are achieved by the resulting axon diameter distribution probability maps.

3126.   51 Pinning Down Specificity of Biomarkers to Axon and Myelin Damage: Preliminary Results
Gemma Nedjati-Gilani1, Torben Schneider2, Bernard M. Siow1,3, Mohamed Tachrount4, Andrew Davies2, Kenneth J. Smith2, Ying Li4, Olga Ciccarelli4, David L. Thomas4, Daniel C. Alexander1, and Claudia Angela M. Wheeler-Kingshott2
1Centre for Medical Image Computing, Department of Computer Science, University College London, London, United Kingdom, 2NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Institute of Neurology, London, United Kingdom, 3Centre for Advanced Biomedical Imaging, University College London, London, United Kingdom, 4Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, London, United Kingdom

This works tests the feasibility of parameters from diffusion MR such as exchange time lower case Greek taui and axonal density f as biomarkers for axonal loss and demyelination, using an animal model of axonal loss in the spinal cord. Preliminary results show a significant decrease in f in regions of axon loss. Exchange time also decreases, but is not necessarily significant. This suggests that f is a potentially useful biomarker of axonal degeneration. Future work will extend the methodology to investigate demyelination.

3127.   52 Characterizing Microstructure by a Time-Dependent Transverse Relaxation Rate
Alexander Ruh1, Philipp Emerich1, Dmitry S. Novikov2, and Valerij G. Kiselev1
1Department of Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany, 2Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States

The correlation time of diffusing spins in magnetically heterogeneous tissues is often commensurate with the timing of MRI experiments. This results in a time dependent transverse relaxation rate that for long times approaches the monoexponential limit. Here we show that the power law of this approach represents the statistics of large-scale organization of magnetic microstructure. The origin of this effect is the self-averaging, which is inherent to diffusion narrowing, when spins are exploring microstructure via diffusion. The present results enable an analysis scheme alternative to a previously proposed spectral domain approach, which enlarges options for future quantifications.

3128.   53 Using in-vivo Human Brain Data to Select Diffusion MRI Compartment Models
Uran Ferizi1,2, Torben Schneider2, Eleftheria Panagiotaki1, Gemma Nedjati-Gilani1, Hui Zhang1, Claudia Angela M. Wheeler-Kingshott2, and Daniel C. Alexander1
1Centre for Medical Image Computing and Department of Computer Science, University College London, London, England, United Kingdom, 2NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Institute of Neurology, London, England, United Kingdom

Finding models that are more descriptive than the standard Diffusion Tensor is necessary in producing better disease biomarkers that provide more specificity to the physiological changes and sensitivity to the pathological impact of the disease in the body. This work investigates which compartment models of diffusion MRI are best at describing the signal from in-vivo human brain white matter, and how reproducible these results are across acquisition sessions.This study helps clinicians and medical physicists in choosing models for future in-vivo brain microstructure imaging.

3129.   54 Multimodality Investigation of Microstructures by the Combination of Diffusion NMR and Diffuse Optical Spectroscopy
Alessandro Proverbio1, Bernard M. Siow2, Daniel Alexander3, and Adam Gibson1
1Department of Medical Physics and Bioengineering, University College London, London, United Kingdom, 2Centre for Advanced Biological Imaging, University College London, London, United Kingdom, 3Centre for Medical Image Computing and Department of Computer Science, University College London, London, United Kingdom

Non-invasive histology is a key research area. Diffusion NMR (dNMR) and Diffuse Optical Spectroscopy (DOS) can provide complementary information about the microstructure of a tissue using different contrast mechanisms. Here, we developed a biophysical model of the microstructure directly informed by dNMR and DOS signals, and we applied it to a sample to estimate three microstructural parameteres. This is a proof of concept that a low level combination of information obtained from dNMR and DOS can improve the accuracy of parameters estimatation. The model was developed in order to allow an extention to real tissues microstructure.

3130.   55 Differentiation Between Apoptotic and Non-Apoptotic Cell Death Using Diffusion-Weighted MR
Sato Eida1, Marc Van Cauteren2, Yuka Hotokezaka1, Makoto Obara2, Tomoaki Okuaki2, Ikuo Katayama1, Miho Sasaki1, Misa Sumi1, and Takashi Nakamura1
1Radiology and Cancer Biology, Nagasaki university, nagasaki, nagasaki, Japan, 2Philips Electronics, tokyo, tokyo, Japan

The area and integrity of the plasma membranes, as quantified by the total CPL, are critical determinants of the diffusion characteristics on the cellular level. The evolution over time of the ADC values is characteristic of whether the cells die via apoptotic or non-apoptotic (necrotic) pathway. Therefore, this can be used as a cancer biomarker for differentiating between different pathways of cell death, e.g. in testing the effects of cancer drugs in vitro.

3131.   56 High-Resolution Diffusion Kurtosis Imaging (DKI) Enabled by Segmented Position Orientation Adaptive Smoothing (POAS)
Siawoosh Mohammadi1, Karsten Tabelow2, Thorsten Feiweier3, Joerg Polzehl2, and Nikolaus Weiskopf1
1Wellcome Trust Centre for Neuroimaging at UCL, ION UCL, UCL, London, London, United Kingdom, 2Weierstrass Institute for Applied Analysis and Stochastics, Berlin, Berlin, Germany, 3Healthcare Sector, Siemens AG, Erlangen, Bayern, Germany

Recent studies suggest that Diffusion Kurtosis Imaging (DKI) is more sensitive to gray microstructure than the well-known diffusion tensor imaging (DTI). However, DKI suffers from a low signal-to-noise ratio (SNR), since it is based on multiple and high b-value data. Thus, in-vivo high-resolution DKI with small voxel sizes has not been available on clinical scanners. We aimed to overcome the low SNR issue by using a novel version of the position orientation adaptive smoothing (POAS), which is separately applied on grey and white matter masks.

3132.   57 Exact Analytical Results for ADC for Oscillating Diffusion Sensitizing Gradients
Alexander L. Sukstanskii1
1Radiology, Washington University, St. Louis, Missouri, United States

Apparent diffusion coefficient (ADC) is analyzed for the case of oscillating diffusion sensitizing gradients. The exact analytical expressions are obtained for the high-frequency expansion of ADC for an arbitrary number of oscillations. The validity conditions of the high-frequency expansion of ADC are analyzed. It is shown that these conditions are substantially different for cos- and sin-type gradients. For the cos-type gradients, the high-frequency regime is reached whenT<<tD (T is the period of oscillations, tD is the characteristic diffusion time), whereas for the sin-type gradients, this regime is achieved when the total diffusion time t is smaller tD.

3133.   58 Evaluation of the Biexponential Model for the Description of Diffusion Data Acquired with Multiple B-Values
Letizia Squarcina1, Denis Peruzzo1, Filippo Arrigoni2, Fabio Triulzi3, and Alessandra Bertoldo1
1Department of Information Engineering, University of Padova, Padova, Italy, Italy, 2Neuroimaging Unit, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy, 3Neuroimaging Unit, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milano, Italy, Italy

The aim of this work is to understand if diffusion brain data are better described by a bi-exponential model rather than with the conventional mono-exponential. We investigate if all brain areas or only a critical portion of them benefit from the more complicated bi-exponential model and if the derived diffusion indexes obtained with the two models are comparable. The bi-exponential model resulted to fit the data significantly better in all brain areas, with a higher impact in term of diffusion indexes on those where the estimated fraction volume suggests two components.

3134.   59 Investigation of Diffusion Kurtosis Imaging of the Organ with Plenty of Perfusion/flow Effect
Yuriko Suzuki1 and Marc Van Cauteren2
1Philips Electronics Japan, Minato-ku, Tokyo, Japan, 2Philips Healthcare Asia Pacific, Minato-ku, Tokyo, Japan

Diffusion Kurtosis Imaging (DKI) is a method to study the deviation of water diffusion from Gaussian distribution, which has been successfully applied to several brain diseases recently. However, in the organ with plenty of flow, DKI curve fitting is ruined. The aim of study is to define the DKI model which consider perfusion/flow component, and using this model, investigate how the conventional DKI fitting is affected by perfusion/flow. Our study has shown that large perfusion/flow fraction induced lower R2 of fitting, overestimated D and large error of estimated K.

3135.   60 Does the Signal Arising from a Single Fascicle Significantly Deviates from a Monoexponential Decay with a Clinical Scanner?
Benoit Scherrer1, Maxime Taquet1,2, Onur Afacan1, and Simon K. Warfield1
1Computational Radiology Laboratory, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States, 2ICTEAM Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium

Multiple works have shown that the diffusion attenuation in a voxel significantly deviates from a monoexponential decay. However, when imaging with a clinical scanner with long δ, it is not clear that the signal arising from a single fascicle is non-monoexponential. We hypothesize that the non-monoexponential behavior observed in voxels may reflect predominantly the presence of multiple fascicles with heterogeneous orientation and the presence of an additional compartment that is macroscopically isotropic. We imaged a region containing a single fascicle orientation, the body of the corpus and investigated the residual diffusion decay after subtracting the contribution of unrestricted diffusion.

3136.   61 Microstructural Information by Double-Pulsed-Field-Gradient NMR: from Model Systems to Nerves
Darya Morozov1, Leah Bar2, Nir Sochen2, and Yoram Cohen1
1School of Chemistry, Tel Aviv University, Tel Aviv, Israel, 2School of Mathematical Sciences, Tel Aviv University, Tel Aviv, Israel

Diffusion NMR is a powerful tool for gleaning microstructural information on opaque systems. We demonstrate that our modeling of d-PFG MR experiments, performed on a series of phantoms of increasing complexity where the ground truth is known a priori, can, without assuming the number of compartments, identify the number of restricted compartments, detect their sizes and determine their relative populations. In addition the model can identify free diffusion when presents in addition to the restricted compartments. This model was then used to study diffusion in excised nerves, showing that it provides a mean to obtain detailed microstructural information in nerves.

3137.   62 Nerve Microstructure: Modeling of the Diffusion MR Signal in Calibrated Model Systems and Nerves
Darya Morozov1, Leah Bar2, Nir Sochen2, and Yoram Cohen1
1School of Chemistry, Tel Aviv University, Tel Aviv, Israel, 2School of Mathematical Sciences, Tel Aviv University, Tel Aviv, Israel

Diffusion NMR is a powerful tool for gleaning microstructural information on opaque systems. We demonstrate that our modeling of s-PFG MR experiments, performed on a series of phantoms of increasing complexity where the ground truth is known a priori, can, without assuming the number of compartments, identify the number of restricted compartments, detect their sizes and determine their relative populations. In addition the model can identify free diffusion when presents in addition to the restricted compartments. This model was then used to study diffusion in excised nerves, showing that it provides a mean to obtain detailed microstructural information in nerves.

3138.   63 Monte-Carlo Simulation of Susceptibility Effects on the PGSE Signal and Diffusion Measures
Pim Pullens1,2, Alard Roebroeck2, Rainer Goebel2, and Kamil Uludag2
1Biomedical MR Imaging and Spectroscopy Group, Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands, 2Maastricht Brain Imaging Center, Maastricht, Netherlands

The susceptibility in white matter fiber is orientation-dependent and, thus, affects the gradient-echo signal. Rotating a fibrous phantom in the magnetic field, we also observed signal changes in diffusion-weighted spin-echo experiments. Consequently, diffusion parameters, such as FA and ADC, can be distorted by these orientation-dependent effects. In the study, Monte-Carlo simulations were performed to investigate the effect of susceptibility changes in a PGSE experiment. We found in our simulations that diffusion-weighted signal, FA and ADC change as a result of susceptibility differences. This could have an impact on human DW-MRI measurements especially at high and ultra-high fields.

3139.   64 Explicit Formula for Diffusion Orientation Distribution Function Using a Kurtosis Approximation
Jens H. Jensen1,2, Ali Tabesh1,2, and Joseph A. Helpern1,2
1Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, United States, 2Center for Biomedical Imaging, Medical University of South Carolina, Charleston, SC, United States

The diffusion orientation distribution function (dODF) can be used to estimate the directions of axonal fiber bundles and may be combined with white matter fiber tractography algorithms. Here a new analytical representation for the dODF is presented that includes the leading non-Gaussian corrections through the diffusional kurtosis tensor. By using numerical simulations, it is shown that including the non-Gaussian corrections both improves the accuracy of the predicted fiber bundle directions and allows for the direct quantification of intra-voxel fiber crossings. This explicit formula for the dODF may be of utility when diffusional kurtosis imaging data is available.

3140.   65 The Influence of Macroscopic and Microscopic Fibre Orientation Dispersion on Diffusion MR Measurements: A Monte-Carlo Simulation Study
Tingting Wang1, Hui Zhang1, Matt G. Hall1, and Daniel C. Alexander1
1University College London, London, United Kingdom

Two classes of fibre orientation dispersion are observed in biological tissue: 1) Macroscopic dispersion, a population of straight fibres with different orientation, e.g. crossing and fanning fibres. 2) Microscopic dispersion, individual fibres with varying orientation, e.g. undulating fibres. Current reconstruction techniques implicitly assume macroscopic dispersion. Here we construct virtual tissue environments and conduct Monte-Carlo simulations to study differences that arise in the water dispersion, FA, and parameter estimates from biophysical models. Our results suggest that, the ODF can be recovered accurately in macroscopic dispersion, but not with small scale microscopic dispersion. We suggest considering such effects in future modelling works.

3141.   66 Monte Carlo Simulation of White Matter as a Composite Porous Medium
Gregory T. Baxter1 and Lawrence R. Frank1
1Radiology, UCSD, La Jolla, CA, United States

Sen and Basser developed a theoretical model for diffusion in white matter in the brain in the long-time limit. Their model represents white matter fascicles as coated cylinders in periodic arrays, with distinct axonal core, myelin sheath, and surrounding medium. We implement this white matter model in a Monte Carlo diffusion simulator to find results in the context of DTI. Anisotropy calculated from numerical simulations matches the theoretical model in the long-time limit, but anisotropy is significantly understated when diffusion time is short. Anisotropy is also sensitive to the concentration of spins in the myelin sheath.

3142.   67 Numerical Simulation of DMRI Signals in a Complex Tissue Model
Jing-Rebecca Li1 and Denis Le Bihan2
1Equipe DEFI, INRIA Saclay, Palaiseau Cedex, Palaiseau Cedex, France, 2NeuroSpin, CEA, Gif-sur-Yvette Cedex, Gif-sur-Yvette Cedex, France

We numerically simulated the magnetization of diffusing water molecules in a two compartment tissue model consisting of permeable cells, with cylindrical and spherical shapes, and extra-cellular space subject to the pulsed gradient spin echo (PGSE) sequence at various diffusion times by numerically solving the Bloch-Torrey partial differential equation using a finite volume spatial discretization coupled with a Runge-Kutta Chebyshev time-stepping method. The simulated results are consistent with experimental findings in rat cortex in vivo.

3143.   68 Selective Sensitivity of Diffusion-Weighted MRI to Various Length Scales in Tumors Following Treatment
Junzhong Xu1 and John C. Gore1
1Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States

Many practical anti-cancer treatments induce tumor microstructural variations at both supra- and subcellular levels, and detecting changes across different length scales is likely to provide more comprehensive information about tumor status. In this study, we used histology-based simulations and imaging in vivo of mouse xenografts to demonstrate the importance of probing various length scales of tumors. The results suggest that, in order to obtain comprehensive information about tumor status or to maximum the sensitivity for monitoring tumor response to treatment, diffusion measurements with a broad range of diffusion times may be necessary

3144.   69 The Anomalous Diffusion Parameter lower case Greek alpha Provides the Most Relevant Information of Structural Complexity in Heterogeneous Media
Marco Palombo1,2, Andrea Gabrielli3, Giancarlo Ruocco1,2, and Silvia Capuani1,2
1Physics Department, Sapienza University, Rome, Rome, Italy, 2CNR IPCF UOS Roma, Sapienza University, Rome, Rome, Italy, 3ISC-CNR, Rome, Rome, Italy

The anomalous diffusion parameter lower case Greek alpha, which quantifies sub-diffusion processes was investigated as a function of the sphere-density lower case Greek phi. We demonstrated, by using numerical simulation and experimental results that, unlike conventional tortuosity investigations based on long diffusion time behavior of D(t)/D0, lower case Greek alphaquantifies the global structural complexity (disorder) of heterogeneous systems. Moreover, we showed that lower case Greek alpha can be measured by using Capital Greek Delta-varying PFG experiment which is faster than the diffusion time behavior of D(t)/D0 study. As a consequence we speculate that our approach could be used as a new tool to probe changes in microstructural properties in healthy and pathological tissues.

3145.   70 Improvement of Diffusion Spectrum Imaging Using Bi-Exponential Diffusion Weighting
Kwan-Jin Jung1
1Psychology, Carnegie Mellon University, Pittsburgh, PA, United States

The brain tissue is known to be bi-exponential in diffusion weighting at a high b value. The diffusion spectrum imaging (DSI) employs a wide range of b values with a peak value greater than 5000 and hence the diffusion in DSI should be considered to be bi-exponential. However, the conventional analysis of DSI has not considered the bi-exponential diffusion weighting. The bi-exponential diffusion weighting in DSI has been accounted for by replacing the acquired b with an adjusted b* which can be obtained by a simple nonlinear curve fitting. The bi-exponentially adjusted b* was experimentally confirmed to be effective in improving the fiber tracts particularly through the multiple fiber crossing regions.

3146.   71 Correlation Time Vs. Pulsed Field Gradient Diffusion MRI of the Brain: On the Effects of Magnetization Transfer and Myelination as a Function of Age
Hazem Eltawell1, Stephan Anderson1, Osamu Sakai1, and Hernan Jara1
1Boston University Medical Center, Boston, MA, United States

The aim of our work was to discern the effects of the brain growth and development on global diffusion coefficients measured by correlation time technique DCT, in comparison to the standard DPFG technique. 27 subjects (0.5 to 24 years old) brains were scanned using 1.5 T scanner, DW-SE-sshEPI, and mixed-TSE pulse sequence, images were processed by qMRI algorithm to produce parametric maps used to calculate global DPFG and DCT histograms. Statistical analysis of the Peak DPFG and DCT histograms gives a power fit with different degrees of correlation, R2=0.92; R2=0.47 respectively, and maximum 17% age (myelination) related difference.

3147.   72 Distinguishing Small Pore Sizes Using Oscillating Gradient Spin Echo Sequences
Sheryl L. Herrera1, Trevor J. Vincent2, Jonathan D. Thiessen1,3, Richard Buist3, and Melanie Martin2,4
1Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada, 2Physics, University of Winnipeg, Winnipeg, Manitoba, Canada, 3Radiology, University of Manitoba, Winnipeg, Manitoba, Canada, 4Radiology, Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada

Oscillating gradient spin echo (OGSE) sequences probe the shortest possible diffusion time scales so that the transition from restricted to hindered diffusion within the smallest structures can be detected. Here we simulate different geometries using OGSE sequences to determine the ability of the OGSE sequences to distinguish small pore sizes. As expected, OGSE frequencies corresponding to scales in the range between completely restricted and free diffusion best distinguish restriction sizes. Combining these measurements with other techniques such as AxCaliber and ActiveAx can allow for the inference of restriction sizes in the samples.


Monday, 22 April 2013 (15:15-16:15) Exhibition Hall
Fiber ODF & Fiber Tracking

  Computer #  
3148.   49 RESDORE: Robust Estimation in Spherical Deconvolution by Outlier Rejection
Greg D. Parker1,2, David Marshall2, Paul L. Rosin2, Nicholas Drage3, Stephen Richmond3, and Derek K. Jones1
1CUBRIC, School of Psychology, Cardiff University, Cardiff, South Glamorgan, United Kingdom, 2School of Computer Science, Cardiff University, Cardiff, South Glamorgan, United Kingdom, 3School of Dentistry, Cardiff University, Cardiff, South Glamorgan, United Kingdom

We present a novel method for robust estimation of fibre orientation distribution functions through diffusion weighted signal outlier rejection. Our algorithm combines aspects of the Richardson-Lucy spherical deconvolution with a non negative sparse coder to produce an adaptive signal dictionary that 'learns' compensations for common non-axially symmetric noise/corruption while preserving signals arising from complex fibre architecture. This has the effect of improving both fODF estimation and (by studying the dictionary adaptations) the robustness of outlier identification.

3149.   50 Robust Fiber Response Function Estimation for Deconvolution Based Diffusion MRI Methods
Chantal M.W. Tax1, Ben Jeurissen2, Max A. Viergever1, and Alexander Leemans1
1Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands, 2Department of Physics, University of Antwerp, iMinds-Vision Lab, Antwerp, Belgium

Spherical deconvolution techniques characterize complex fiber configurations within a voxel. Currently, the response function (RF) needed for deconvolution is derived from voxels with the highest fractional anisotropy (FA). Poor accuracy of FA in the high b-value and low SNR regime and the ad-hoc nature of selecting these voxels complicate RF estimation, which may lead to the detection of false positive peaks and altered peak magnitudes. In this work, the computation of the RF is optimized by excluding "crossing fibers" voxels in a recursive framework, which does not rely on FA. Feasibility is demonstrated on simulated and real diffusion MRI data.

3150.   51 Knowledge-Based Tractography Using Path Finding by Dynamic Programing
Muwei Li1, J. Tilak Ratnanather2, Yajing Zhang1, Hangyi Jiang1, Kenichi Oishi1, Michael I. Miller2, and Susumu Mori1
1The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 2Center for Imaging Science, Johns Hopkins University, Baltimore, MD, United States

A knowledge-guided path-finding approach is proposed in this study. Combined with the automated brain segmentation, this approach can automatically generate 106 tracts based on our anatomical knowledge.This tool can be used to investigate tract-specific white matter anatomical states in various brain disorders.

3151.   52 Assessment of Local Fiber Plausibility Using a HARDI Based Reference
Peter F. Neher1, Bram Stieltjes2, Ivo Wolf3, Hans-Peter Meinzer1, and Klaus Hermann Fritzsche1,2
1Medical and Biological Informatics, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Quantitative Image-based Disease Characterization, German Cancer Research Center (DKFZ), Heidelberg, Germany, 3Medical Informatics, Mannheim University, Mannheim, Germany

Evaluation of diffusion MRI-based tractography methods is challenging and existing approaches for quantitative assessment mainly focus on measures of general tract overlap or the presence of anatomically plausible connections between brain regions. We present an evaluation of the local fiber direction plausibility on a voxel-wise basis. We further propose a reference-based validation procedure that aims at evaluating tractograms obtained from data of clinical quality using high quality HARDI data as a reference.

3152.   53 A Variational Bayesian Approach to Network Modularity Applied to the Structural Connectome of the Human Brain
Etay Ziv1, Julia P. Owen1, Yi-Ou Li1, Eric J. Friedman2, and Pratik Mukherjee1
1University of California, San Francisco, San Francisco, California, United States, 2International Computer Science Institute, Berkeley, California, United States

We apply a Variational Bayesian approach to modularity analysis of the structural connectome in normal adult subjects and compare this VBMOD algorithm to the two most widely used module detection algorithms within the brain network community. We demonstrate the superiority of VBMOD to these existing methods in precision, accuracy and robustness to noise, both in module identification and cardinality inference. These findings are consistent over a broad range of thresholds used to binarize the networks. Our results are of interest to researchers in the connectomics and diffusion tractography literature.

3153.   54 Towards a Super-Resolution CONNECT/ARCHI Atlas of the White Matter Connectivity
Delphine Duclap1, Benoit Schmitt1, Alice Lebois1, Pamela Guevara2, Hui Zhang3, Clarisse Longo Dos Santos1, Denis Le Bihan1, Jean-François Mangin1, and Cyril Poupon1
1I2BM, CEA NeuroSpin, Gif-sur-Yvette, France, 2University of Concepción, Concepción, Chile, 3Department of Computer Science and Centre for Medical Image Computing, University College London, London, United Kingdom

Super-resolution techniques now provide an efficient strategy to improve the spatial resolution of individual diffusion maps. We extended this approach to a population of subjects and proposed a novel half-millimeter isotropic probabilistic atlas of the human brain connectivity, using the ARCHI database acquired in the frame of the European CONNECT connectome project. We demonstrate the efficacy of this approach combining a super-resolution technique based on high density streamline tractography and a robust segmentation technique of the white matter bundles.

3154.   55 Towards Probabilistic Atlases of the T1/T2 Relaxation Times from the CONNECT/ARCHI Database
Alice Lebois1, Delphine Duclap1, Benoit Schmitt1, Clarisse Longo Dos Santos1, Pamela Guevara2, Hui Zhang3, Denis Le Bihan1, Jean-François Mangin1, and Cyril Poupon1
1I2BM, CEA-NeuroSpin, Gif-Sur-Yvette, France, France, 2University of Concepcion, Concepcion, Chile, Chile, 3Department of Computer Science and Centre for Medical Image Computing, University College of London, London, United Kingdom

This work is focused on the construction of two probabilistic atlases of the quantitative T1 and T2 parameters of the human brain from the relaxometry data of the CONNECT/ARCHI database, an open MRI database of 79 healthy subjects built under the framework of the European CONNECT project which aims at inferring the connectome atlas of the human brain from functional and anatomical MRI data at 3T. We combined these atlases to density maps of the major white matter bundles we extracted from the diffusion data of the 79 subjects to compute the average T1/T2 relaxation times for each bundle.

3155.   56 A Novel Probabilistic Connectivity Atlas for the Human Connectome : The CONNECT/ARCHI Atlas
Benoit Schmitt1, Delphine Duclap1, Alice LEBOIS*1, Pamela Guevara2, Hui Zhang3, Yaniv Assaf4, Fabrice POUPON1, Denis Riviere1, Yann Cointepas1, Denis Le Bihan1, Jean-François Mangin1, and Cyril POUPON1
1I2BM, CEA - NeuroSpin, GIF-SUR-YVETTE, FRANCE, France, Metropolitan, 2University of Concepcion, CONCEPCION, CHILE, Chile, 3Department of Computer Science & Centre for Medical Image Computing, University College London, LONDON, UNITED KINGDOM, United Kingdom, 4Department of Neurobiology, Tel-Aviv University, TEL-AVIV, ISRAEL, Israel

Providing a map of the human connectome is today a major challenge of diffusion. To reach this goal, two projects were launched: Human Brain Connectome in the USA and CONNECT project in Europe. This study was done in the frame of CONNECT project and included 79 subjects. In this study, we built the first probabilistic atlas of the human brain connectivity and diffusion quantitative statistics along bundles. We believe this novel atlas will help to infere the human brain connectome and further to provide some microstructural information for each bundle.

3156.   57 Multi-Fascicle Model Reconstruction from Acquisitions of DWI at a Single B-Value with a Population-Informed Prior
Maxime Taquet1,2, Benoit Scherrer1, Benoit Macq2, and Simon K. Warfield1
1Computational Radiology Laboratory, Harvard Medical School, Boston, Massachusetts, United States, 2ICTEAM Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium

DTI are unable to distinguish fascicles crossing in one voxel, making them impractical to study the white matter microstructure and the brain connectivity. Multi-tensor models are a valuable option in these contexts. However, their reconstruction requires acquisitions of DWI at multiple b-values, unlike all datasets acquired with a single-shell HARDI sequence. This results in a waste of money, effort and imaging time. In this study, we propose a method to circumvent the multiple b-values requirement, allowing the community to use their existing datasets to reconstruct multi-fascicle models and conduct further analyses of the white matter at no additional cost.

3157.   58 Construction of a Fiber Atlas of the Murine Heart
Stelios Angeli1, Nicholas Befera2, Gary Cofer2, G. Allan Johnson2, and Christakis Constantinides1
1University of Cyprus, Nicosia, Nicosia, Cyprus, 2Radiology, Duke University Medical Center, Durham, NC, United States

The unique myocardial architecture, comprised of oriented laminar sheets and helical spiral tracts of fibers, accounts for its efficient contractile and torsional mechanical function. The inherent structural-functional associations of the heart also underline the potential significance of fiber tractography in remodeling or cellular disarray, following early, or late pathological states. Diffusion MRI tractography can provide 3-dimensional (3D) mapping of the myofiber structure . This study employs 3D, microscopic, spin-echo, diffusion-weighted MRI to construct a fiber atlas of the ex-vivo, fixed, C57BL/6 murine heart.

3158.   59 Tractography-Based Voxel-Wise Analysis (TBVA): A New Approach for Detecting White Matter Abnormalities in Clinical Populations
Su-Chun Huang1,2, Gregory J. Pauley1, Todd L. Richards1, Neva M. Corrigan3, Dennis W. Shaw3, Alan A. Artru4, Annette Estes5, Stephen R. Dager3, and Natalia M. Kleinhans1,3
1Integrated Brain Imaging Center, Department of Radiology, University of Washington, Seattle, WA, United States, 2Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan, 3Department of Radiology, University of Washington, Seattle, WA, United States, 4Department of Anesthesiology, University of Washington, Seattle, WA, United States, 5Speech and Hearing Sciences, University of Washington, Seattle, WA, United States

Here we introduce a new analysis pipeline named tractography-based voxel-wise analysis (TBVA), which combines the advantages of TBSS and probabilistic tractography. This approach shows individual tract bundles in MNI standard space and performs voxel-wise comparisons within the tract bundle. We employed TBVA on the cingulum bundle (CB) in a group of participants with autism spectrum disorders (ASD) and age and IQ matched controls, and compared the results from conventional TBSS to the TSVA tractography results.

3159.   60 Microstructure-Informed Slow Diffusion Tractography in Humans Enhances Visualisation of Fibre Pathways
Farida Grinberg1, Ivan I. Maximov1, Ezequiel Farrher1, and Nadim Jon Shah1,2
1Institute of Neuroscience and Medicine 4 - Medical Imaging Physics, Forschungszentrum Juelich, Juelich, Germany, 2Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany

Diffusion-based tractography is restricted by an uncertainty of determination of the diffusion directionality in the regions where fibre alignment anisotropy is low or fibre configuration is complex. In this work, we exploit the higher fractional anisotropy of the slow diffusion component which refers, in frame of the established models, to the restricted axonal water fraction. We show that advanced, model-based fibre tracking allows one to enhance reliability and visualisation of various fibre tracks, especially at the borders between white and grey matter. Potential benefits are discussed also in the context of combined functional and structural connectivity studies.

3160.   61 Evaluating the Accuracy of White-Matter Connectomes
Franco Pestilli1, Jason Yeatman1, Ariel Rokem1, Kendrick Kay1, and Brian Wandell2
1Psychology, Stanford University, Stanford, CA, United States, 2Psychlogy, Stanford University, Stanford, CA, United States

We propose a method to evaluate the accuracy of white-matter connectomes generated using diffusion weighted MRI and fiber tractography. The method predicts the diffusion data in each voxel as a weighted sum of the contributions from all the fascicles in that voxel. We derive several connectomes using different tractography algorithms (TEND, FACT and CSD). We evaluate each connectome using cross-validation with respect to a second set of diffusion measurements in the same subject. Connectomes generated using the CSD algorithm with an intermediate order of spherical harmonic basis set (4>lmax<16) predicts diffusion measurements better than data reliability.

3161.   62 Large Deformation Diffeomorphic Metric Mapping for Unlabeled Curves: Application to Fiber Tract Bundles
Yung-Chin Hsu1 and Wen-Yih Isaac Tseng1,2
1Center for Optoelectronic Biomedicine, College of Medicine, National Taiwan University, Taipei, Taiwan, 2Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan

A registration method for unlabeled curves under the LDDMM framework is proposed, and this method is applied to register two right cingulum bundles for demonstration. The results show that the proposed method could effectively transform the tract bundles so that the global shapes are matched well. By registering the tract bundles to a common space, this method would be a valuable tool to investigate the brain morphology, which is a hot topic in neuroimaging studies in development, ageing or mental disorders.

3162.   63 Fiberfox: A Novel Tool to Generate Software Phantoms of Complex Fiber Geometries
Peter F. Neher1, Bram Stieltjes2, Frederik B. Laun3, Hans-Peter Meinzer1, and Klaus Hermann Fritzsche1,2
1Medical and Biological Informatics, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Quantitative Image-based Disease Characterization, German Cancer Research Center (DKFZ), Heidelberg, Germany, 3Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany

We present an interactive graphical tool, Fiberfox, to generate arbitrary fiber configurations and corresponding diffusion weighted images (DWI). The intuitive user interface allows for the generation of any number of straight, bended, crossing, kissing, twisting and fanning fiber bundles, simply by placing 3D-ROIs used as waypoints for the synthetic fibers. From these fibers, a DWI is calculated applying a user defined number of gradient directions, b-value, SNR, image size and spacing. Fiberfox is implemented in the open source medical imaging interaction toolkit (MITK) and will also be available as free download included in the next release of MITK Diffusion.

3163.   64 Reconstructing Cerebellar-Cortical Connections with Advanced Diffusion Tractography
Fulvia Palesi1,2, Donald Tournier3,4, Fernando Calamante4,5, Niels Muhlert6, Gloria Castellazzi2,7, Declan T. Chard6, Egidio Ugo D'Angelo2,8, and Claudia Angela M. Wheeler-Kingshott6
1Department of Physics, University of Pavia, Pavia, Italy, 2Brain Connectivity Center, IRCCS C. Mondino, Pavia, Italy, 3Melbourne Brain Centre - Austin Campus, The Florey Institute of Neuroscience and Mental Health, Heidelberg, Victoria, Australia, 4Department of Medicine, Austin Health and Northern Health, University of Melbourne, Melbourne, Australia, 5Melbourne Brain Centre - Austin Campus, Florey Institute of Neuroscience and Mental Health, Heidelberg, Victoria, Australia, 6NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Institute of Neurology, London, United Kingdom,7Department of Industrial and Information Engineering, University of Pavia, Pavia, Italy, 8Department of Public Health, Neuroscience, Experimental Medicine, University of Pavia, Pavia, Italy

The study of cerebellum’s connectivity networks is challenging. This study assessed the feasibility of using advanced diffusion imaging methods to reconstruct whole contralateral cerebellar-cortical tracts in vivo. We combined two techniques: track reconstruction with constrained spherical deconvolution (CSD) algorithm and seed/target placement through the creation of super-resolution maps using track density imaging (TDI). We reconstructed tracts by placing ROIs both on b0 and TDI images: tracts appeared more anatomically accurate when using TDI maps rather than b0 images and inter-subject variability of cerebellar FA was found to be more reproducible when using ROIs placed on TDI.

3164.   65 A Multiple-Fibre Diffusion Phantom for the Validation of HARDI Methods -permission withheld
Ezequiel Farrher1, Farida Grinberg1, A. Avdo Celik2, Kaveh Vahedipour2, and Nadim Jon Shah2,3
1Institute of Neuroscience and Medicine 4 - Medical Imaging Physics, Forschungszentrum Juelich, Jülich, Germany, 2Institute of Neuroscience and Medicine 4 - Medical Imaging Physics, Forschungszentrum Jülich, Jülich, Germany, 3Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany

We present a new multiple-fibre design of an anisotropic fibre phantom for diffusion MRI applications. The valuable feature of the new design relates to the integration of several geometrical configurations and fibre populations in a single device. We have demonstrated the application of the design in the analysis of high angular resolution diffusion imaging (HARDI) data analysis methods. The new phantom is shown to be an excellent tool for the investigation and comparison of several of HARDI methods as well as fibre tractography algorithms.

3165.   66 Comparison Study of Two DTI Tractography Methods for Quantifying Brain Structural Connectivity
Qing Ji1, John O. Glass2, and Wilburn E. Reddick1
1Radiological Science, St.Jude Children's Research Hospital, Memphis, TN, United States, 2Radiological Science, St. Jude Children's Research Hospital, Memphis, TN, United States

In this study, deterministic and probabilistic tractography algorithms for measuring brain structural connectivity were quantitatively evaluated on data from 8 healthy subjects. Eighty-two brain anatomic structures were obtained on each subject using FreeSurfer and connections between these structures were calculated by both tractography techniques. Neuroanatomical connectivity metrics between the two tractography methods were significantly correlated and fiber tracks from the deterministic algorithm were spatially similar to fiber probability distributions created using the probabilistic algorithm. While there was a high degree of correspondence between the approaches, the probabilistic algorithm provides more connections among brain structures and the additional information of uncertainty.

3166.   67 Analysis of Tractography Biases Introduced by Anisotropic Voxels
Peter F. Neher1, Bram Stieltjes2, Ivo Wolf3, Hans-Peter Meinzer1, and Klaus Hermann Fritzsche1,2
1Medical and Biological Informatics, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Quantitative Image-based Disease Characterization, German Cancer Research Center (DKFZ), Heidelberg, Germany, 3Medical Informatics, Mannheim University, Mannheim, Germany

In research settings it is common practice to acquire diffusion weighted images with an isotropic resolution. In contrast, clinical datasets are often acquired with a relatively high in-plane resolution of about 1-2 mm but much thicker slices (2-5 mm). The impact of such anisotropic image resolutions on the outcome of fiber tractography has not been systematically analyzed yet. This work uses software phantom data to quantify the impact of anisotropic voxels on nine different publicly available and commonly used algorithms.

3167.   68 Distortion Correction Improves DTI Visualization of the Microscopic Elements of the Medial Temporal Lobe -permission withheld
Michael Zeineh1, Samantha J. Holdsworth1, Mansi B. Parekh1, Stefan Skare2, and Roland Bammer3
1Stanford, Stanford, CA, United States, 2Neuroradiology, Karolinska University Hospital, Stockholm, Sweden, 3Stanford University, Stanford, CA, United States

Abnormal neuronal connectivity may be important in disease states involving the medial temporal lobes (MTL), including Alzheimer’s disease and temporal lobe epilepsy. Our prior work pushed the resolving power of DTI to near-mm isotropic voxel size and utilized a detailed segmentation to characterize the major subregions and pathways of the MTL. However, DTI data is subject to echo-planar (EPI) distortion that complicates coregistration with structural images, making segmentation difficult. Additionally, this distortion can create inaccuracies in tractography. In this study, we applied distortion-correction to our source EPI data and found improved structural accuracy.

3168.   69 Repeatability and Variability of Graph Metrics in a Test-Retest of Whole-Brain Structural Networks.
Jennifer Andreotti1, Kay Jann1, Lester Melie-Garcia2, Thomas Dierks1, and Andrea Federspiel1
1Dept. of Psychiatric Neurophysiology, University Hospital of Psychiatry / University of Bern, Bern, Bern, Switzerland, 2Neuroinformatics Department, Cuban Neuroscience Center, Havana, Havana, Cuba

Objective: to compare properties and variability of whole-brain structural networks weighted by connectivity density or by communicability. Methods: Graphs nodes are defined by automatic parcellation of the brain while edges are defined by connectivity density or communicability based on the tractography maps. Global and local network properties as well as their variability were computed. Results: results show larger variability between than within subjects for all properties and weightings. Between subjects' variability is slightly reduced in weighted communicability networks. Discussion: This study shows that network measures may be used to compare subjects. Measures extracted with different weightings correlate well.

3169.   70 Test-Retest Reliability of Computational Network Metrics Derived from the Structural Connectome of the Human Brain
Julia P. Owen1, Etay Ziv1, Polina Bukshpun2, Nicholas Pojman2, Mari Wakahiro2, Jeffrey I. Berman3, Timothy Roberts4, Elliott Sherr2, and Pratik Mukherjee1
1Radiology, UCSF, San Francisco, CA, United States, 2Neurology, UCSF, San Francisco, CA, United States, 3Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, United States, 4Radiology, CHOP, Philadelphia, PA, United States

In this study, we evaluate the test-retest reliability of graph theory techniques as applied to the structural connectome of the human brain. We explore unweighted and weighted graph metrics, as well as other measures of consistency, such as edge weights and module assignments. Two cohorts are used, one group (n=10) was scanned twice on the same scanner and the other group (n=5) was scanned once at two different sites, on the same model of scanner with identical acquisition parameters.

3170.   71 How Diffusion Model and Tract Direction Growth Affects Quantitative DTI Parameters in Ataxia
Yu Zhang1, Xue Wang2, Yufen Chen2, Michael Rozenfeld2, Puneet Opal3, and Todd Parrish1,2
1Biomedical Engineering, Northwestern University, Evanston, IL, United States, 2Radiology, Northwestern University, Chicago, IL, United States, 3Neurology, Northwestern University, Chicago, IL, United States

This study how model selection between bedpostx and qboot and direction issue will affect the probabilistic diffusion tractography.

3171.   72 In Vivo Isotropic Resolution Diffuson Tensor Imaging of Mouse Brain at 9.4T
Mingtao Wang1, Caterina Caffes2, Stephen T.C. Wong1,3, and Kelvin K. Wong1,3
1Department of Systems Medicine & Bioengineering, The Methodist Hospital Research Institute, Houston, TX, United States, 2Texas Children's Hospital, Houston, TX, United States, 3Department of Radiology, Weill Cornell Medical College, New York, NY, United States

In vivo diffusion tensor imaging (DTI) is a powerful tool to understand neuroanatomical connectivity and to evaluate neuronal integrity in mouse models. To resolve the complex connectome in a small brain in vivo, high spatial resolution imaging are crucial. We present a high resolution in vivo DTI and tractography method for mouse brain at 150~150~150 ƒÊm3 resolution at 9.4T. The protocol includes a new low-cost elastomeric padding head restrain to significantly reduce head motion. High resolution isotropic diffusion tensor tractography offers high quality fractional anisotropy map and consistent fiber tracking for connectivity studies between brain regions.


Monday, 22 April 2013 (14:15-15:15) Exhibition Hall
Diffusion Acquisition & Analysis

  Computer #  
3172.   73 Flow Sensitive Cine MR Imaging Using Improved Motion Sensitized Driven Equilibrium (IMSDE)
Kazuyuki Endo1, Tomohiko Horie1, Isao Muro1, Yutaka Imai2, Kagayaki Kuroda3, Tetsuo Ogio4, Makoto Obara4, Marc Van Cauteren4, Thomas C. Kwee5, and Taro Takahara6
1Department of Radiological Technology, Tokai University Hospital, Isehara, Kanagawa, Japan, 2Radiology, Tokai University Hospital, Isehara, Kanagawa, Japan, 3Information Science and Technology, Tokai University, Hiratuka, Kanagawa, Japan, 4Philips Healthcare, Minato-ku, Tokyo, Japan, 5Radiology, University Medical Center Utrecht, Utrecht, Utrecht, Netherlands, 6Biomedical Engineering, Tokai University, Isehara, Kanagawa, Japan

Improved Motion Sensitized Driven EquilibriumiiMSDEjis a kind of T2-prep pulse with motion probing gradients. it can be widely used for clinical applications including black-blood vessel wall imaging , lower extremity MR venography , or suppression of flow artifacts in contrast-enhanced studies for brain metastasis detection . The purpose of this study was to investigate basic appropriate parameters and evaluate the feasibility of this technique as gFlow sensitive cine MR imagingh. Flow sensitive cine MR imaging with iMSDE pre-pulse allows visualization of flow phenomena very clearly, which was not able with conventional cine MR imaging.

3173.   74 The Effect of Coil Types and GRAPPA Acceleration in HARDI and Probabilistic Fibertracking
Javier Urriola Yaksic1, Nyoman Dana Kurniawan1, Aiman Al Najjar1, and David C. Reutens1
1Centre for Advanced Imaging, The University of Queensland, Brisbane, Queensland, Australia

Increasing numbers of channels developed for parallel imaging have enabled higher image signal-to-noise ratio and faster acquisition time, while increasing image quality with a reduction of geometrical distortions in EPI sequences. However, little is known about the effects of coil type and acceleration factor to the accuracy of fibertracking of the whole brain. Our results showed that the choice of coil types and acceleration factors are important in quantitative diffusion fibertracking. The increasing number of false aberrant tracks offsets the advantage of shorter acquisition time and inhomogeneity artefacts when the HARDI data was acquired using larger number of acceleration factors.

3174.   75 Self-Correction of B1 Inhomogeneity Artifact in Diffusion-Weighted Imaging Using Double-Angle Excitation
Kun Zhou1 and Wei Liu1
1Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, Guangdong, China

In diffusion-weighted imaging (DWI), B1 inhomogenetiy induced signal nonuniformity artifacts may degrade image quality and affect diagnosis. A modified DW-EPI sequence with build-in double-angle B1+ mapping mechanism is introduced to address this problem. With the modified sequence, the B1 inhomogeneity information can be calculated and used to reduce related artifacts in DWI images.

3175.   76 Diffusion Pore Imaging by Double Wave Vector Measurements
Tristan Anselm Kuder1 and Frederik B. Laun1,2
1Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Quantitative Imaging-Based Disease Characterization, German Cancer Research Center (DKFZ), Heidelberg, Germany

NMR diffusion measurements allow collecting the signal from the whole sample. This mainly eliminates the problem of vanishing signal at increasing resolution. It has been a longstanding question if the exact shape of closed pores can be determined by diffusion measurements. Here, we present a method using short diffusion gradient pulses only, which is able to reveal the shape of arbitrary closed pores. Compared to former approaches, the method has reduced demands on relaxation times due to faster convergence to the diffusion long time limit and allows for a more flexible NMR sequence design since stimulated echoes can be used.

3176.   77 Simultaneous Multi-Slab Acquisition in 3D Multi-Slab Diffusion-Weighted Readout-Segmented Echo-Planar Imaging
Robert Frost1, Peter Jezzard1, David A. Porter2, and Karla L. Miller1
1FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom, 2Healthcare Sector, Siemens AG, Erlangen, Germany

Readout-segmented echo-planar imaging (rs-EPI) acquires robust, high-quality diffusion-weighted images using a navigated, multi-shot acquisition. However, the scan times are extended roughly by the number of readout segments compared to single-shot echo-planar imaging. Here we present simultaneous multi-slab acceleration in a 3D multi-slab rs-EPI sequence that enables full brain coverage in SNR-optimal TR of 1-2s, which is difficult to achieve with conventional 2D or 3D methods. The modified sequence is used to acquire 1.5mm isotropic trace-weighted data with whole-brain coverage.

3177.   78 Improving the Efficiency of Diffusion Spectrum MRI Through Radial Acquisitions in Q-Space
Fernando Emilio Boada1 and Steven Yutzy2
1Radiology, New York University, New York, New York, United States, 2Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States

A sampling and reconstruction scheme for increasing angular resolution in Diffusion Spectrum Imaging is presented and demonstrated at 3T

3178.   79 A k-D Space Acceleration Strategy for HARDI with Compressed Sensing
Tzu-Cheng Chao1,2, Jr-Yuan Chiou3, Cheng-Wen Ko4, Ming-Ting Wu5, Stephan E. Maier3, and Bruno Madore3
1Department of Computer Science and Information Engineering, National Cheng-Kung University, Tainan, Taiwan, 2Institute of Medical Informatics, National Cheng-Kung University, Tainan, Taiwan, 3Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States, 4Department of Computer Science and Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan, 5Department of Radiology, Kaohsiung Veteran General Hospital, Kaohsiung, Taiwan

An accelerated sampling strategy is proposed that can effectively reduce both geometric distortion and scan time in the context of the high Angularly Resolved Diffusion Imaging(HARDI) diffusion-weighted imaging method. The approach combines sampling strategies inspired from accelerated dynamic imaging and from the rossing Fiber Angular Resolution of Intra-Voxel structure (CFRI) algorithm to resolve crossing fibers in a manner that is fast and fairly insensitive to susceptibility-induced field variations and geometric distortion.

3179.   80 Charged Containers for Optimal 3D Q-Space Sampling
Hans Knutsson1 and Carl-Fredrik Westin1,2
1Department of Biomedical Engineering, Medical Informatics, Linköping University, Linköping, Sweden, 2Department of Radiology, BWH, Harvard Medical School, Boston, MA, United States

We have presented a novel method for generating evenly distributed samples in a part of q-space that can be pre-specified in a general way. We have demonstrated the feasibility for two shapes, a sphere and a cube. The results are interesting from several points of view. There is a market tendency for the samples to group in shells indicating that the present work may provide a preferable alternative to recently proposed shell-interaction schemes . The distributions attained for the cube case are far from Cartesian, this may be an advantage in a sparse reconstruction, e.g. compressed sensing, setting.

3180.   81 3 Phase Cycle Diffusion Prepared 3D FSE to Eliminate Diffusion Weighted Image Distortion
Mitsuharu Miyoshi1, Yuji Iwadate1, and Hiroyuki Kabasawa1
1Global Applied Science Laboratory, GE Healthcare Japan, Hino, Tokyo, Japan

B0 inhomogeneity and eddy current produce image distortion in DW-EPI. Diffusion Prepared 3D FSE (DP-Cube) was developed in this study. Diffusion Prepared pulse sequence with 3 phase cycle were used to eliminate image distortion and banding artifact. Flow Compensated MPG gradient and peripheral trigger were used to make the sequence insensitive to motion. Measured ADC value was higher than literature and DW-EPI because of motion artifacts. Distortion free Diffusion weighted images were acquired with DP-Cube.

3181.   82 3D DP-FISP for Diffusion Measurements in MR Microscopy at Ultra-High Field.
Ileana Ozana Jelescu1, Denis Le Bihan1, and Luisa Ciobanu1
1NeuroSpin, Gif-sur-Yvette, Essonne, France

A 3D diffusion-prepared fast imaging with steady-state free precession (DP-FISP) sequence was implemented at 17.2T to perform apparent diffusion coefficient (ADC) measurements in small biological samples (i.e. single cells). The sequence was tested on phantoms with different T1s, including values similar to those of biological tissues, and was compared with a standard diffusion-weighted spin-echo (DW-SE) sequence. The FISP flip angle was optimized for minimal T1 bias in ADC estimation (< 10%) for b-values up to 600 s/mm². Our sequence is less prone to artifacts than EPI and eight times faster than DW-SE. Future improvements include extension to higher b-values.

3182.   83 Scan Time Reduction in 3D Diffusion-Weighted Steady-State Free Precession Imaging Using Constrained Reconstruction
Rafael O'Halloran1, Florian Knoll2, Kristian Bredies3, Rudolf Stollberger2, and Roland Bammer1
1Radiology, Stanford University, Stanford, CA, United States, 2Institute of Medical Engineering, Graz University of Technology, Graz, Austria, 3Department of Mathematics and Scientific Computing, University of Graz, Graz, Austria

3D DTI acquisitions can be lengthy and as the demand for higher-resolution and more encoding directions increases, strategies for reducing scan times will be critical for adoption of these techniques into the clinic. Here undersampled diffusion-weighted SSFP is combined with a TGV2 constrained reconstruction to reduce the scan time by a factor of 4-8. The effect of undersampling on the FA and the direction of the principle eigenvector is investigated and compared to a conventional gridding reconstruction.

3183.   84 Accelerated Diffusional Kurtosis Imaging Using Simultaneous Multi-Slice Echo Planar Imaging
Jian Xu1, George Russell Glenn2, Himanshu Bhat3, Stephen F. Cauley4, Kawin Setsompop5, Ray Lee6, Ali Tabesh2, Jens H. Jensen2, Joseph A. Helpern2, and Keith A. Heberlein7
1Siemens Healthcare USA, New York, NY, United States, 2Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, United States, 3Siemens Medical Solutions, Charlestown, MA, United States, 4A.A. Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Boston, MA, United States, 5A.A. Martinos Center for Biomedical Imaging, Dept. of Radiology, MGH, Boston, MA, United States, 6Princeton University, Princeton, NJ, United States, 7Siemens Healthcare USA, Charlestown, MA, United States

Diffusional kurtosis imaging extends diffusion tensor imaging by quantifying the non-Gaussian behavior of water diffusion. Established DKI acquisition protocols typically use multi-slice 2D EPI with multiple b-values (¡Ý) and typically 30 gradient directions, which requires 7-15 minutes for full brain coverage. Recently a slice-acceleration method acquiring multiple slices simultaneously with the blipped CAIPIRINHA technique and individually reconstructed using the slice GRAPPA reconstruction method was introduced. In this study, the combination of DKI and the aforementioned multi-slice acceleration technique was performed and initial comparisons of the resultant parametric maps are reported.

3184.   85 WITHDRAWN
3185.   86 Diffusion Tensors from Double-PFG of the Human Brain
Carl-Fredrik Westin1,2, Markus Nilsson3, Ofer Pasternak1, and Hans Knutsson2
1Department of Radiology, BWH, Harvard Medical School, Boston, MA, United States, 2Department of Biomedical Engineering, Medical Informatics, Linköping University, Linköping, Sweden, 3Department of Medical Radiation Physics, Lund University, Lund, Sweden

In this work we estimate diffusion tensors from double-PFG diffusion MRI using two types of measurements 1) paris of gradients that are collinear, and 2) pairs of gradients that are non-collinear. It is known from angular double-PFG that compartment shape anisotropy can be measured with varying the angle between the gradient pairs. The ratio between the measurements with 90 degrees (non-collinear) and the one with 0 degrees (collinear), depends on the compartments shape anisotropy. This work provides and alternative to the model of angular double-PFG introducing two different estimation of the diffusion tensor, where the ratio between them is related to the compartment shape anisotropy.

87 Super Resolution Reconstruction from Differently Oriented Diffusion Tensor Datasets
Gwendolyn Van Steenkiste1, Ben Jeurissen1, Jan Sijbers1, and Dirk H.J. Poot2
1iMinds-VisionLab, University of Antwerp, Antwerp, Belgium, 2Biomedical Imaging Group Rotterdam, Erasmus MC - University Medical Center Rotterdam, Rotterdam, Netherlands

Diffusion MRI typically employs large voxels to obtain sufficiently high SNR. Given the large voxel sizes, many voxels consist of a mixture of signals from different anatomical structures. To reduce the partial volume effect and retain high SNR, we propose a super resolution acquisition and reconstruction technique that directly computes high SNR and high resolution DTI parameters from a set of low resolution diffusion MRI data sets. Using simulations we show our technique outperforms direct high resolution acquisition and current super resolution reconstruction techniques which don't take into account the underlying diffusion model.

3187.   88 Assessing Scan-Rescan Reproducibility of the Parameter Estimates from NODDI
Maira Tariq1, Torben Schneider2, Daniel C. Alexander1, Claudia Angela M. Wheeler-Kingshott2, and Hui Zhang1
1Department of Computer Science & Centre for Medical Image Computing, University College London, London, United Kingdom, 2NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Institute of Neurology, London, United Kingdom

NODDI (Neurite Orientation Dispersion and Density Imaging) is a recent diffusion MRI technique for directly quantifying microstructual indices of neurites using clinically feasible acquisition. It has been shown to be able to disentangle the key microstructural contributors to the standard measures from diffusion tensor imaging (DTI). This study assesses the scan-rescan reproducibility of NODDI in healthy subjects in comparison to DTI. The results show that NODDI has high reproducibility comparable to that of DTI.

3188.   89 Convenient B-Value and B-Matrix Computations for Arbitrary Gradient Waveforms: Characterizing Signal Decay Due to Gaussian Diffusion -permission withheld
Evren Ozarslan1 and Thomas H. Mareci2
1Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States, 2Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States

Estimations of apparent diffusion coefficient (ADC) and tensor (ADT) from diffusion-weighted acquisitions necessitate computations of, respectively, the b-value and b-matrix associated with the employed pulse sequence. We show that these important quantities can be conveniently computed for any gradient waveform using a simple algorithm that requires a few lines of code. This is achieved by representing the waveform by a piecewise constant function. With this representation, our technique complements the existing methods commonly used to compute the effects of restricted diffusion, and provides a consistent and convenient framework for studies that aim to infer the microstructural features of the tissue.

3189.   90 On Random Walks and Entropy in Diffusion-Weighted Magnetic Resonance Imaging Studies of Neural Tissue
Carson Ingo1, Richard L. Magin1, Luis Colon-Perez2, William Triplett3, and Thomas H. Mareci3
1Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, United States, 2Department of Physics, University of Florida, Gainesville, FL, United States, 3Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States

We modeled diffusion in neural tissue from the perspective of the continuous time random walk. The characteristic diffusion decay is represented by the Mittag-Leffler function, which does not make a priori assumptions about the governing statistics. We then used entropy as a measure of the anomalous features for the characteristic function. DWI experiments were performed on fixed rat brains using a spectrometer at 17.6 Tesla at b-values arrayed up to 25,000 s/mm^2. In white and gray matter regions, the Mittag-Leffler and entropy parameters demonstrated new information regarding sub-diffusion and produced different image contrast from that of the classical diffusion coefficient.

3190.   91 Application of Multi-Tensor Tract-Based Analysis (MTTA) with Routine Clinical Diffusion MRI
Virendra Mishra1 and Hao Huang1
1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States

Single tensor fractional anisotropy (FA) values are significantly underestimated at the crossing-fiber regions. Single tensor FA, therefore, is biased in characterizing white matter integrity in clinical research. Tract analysis has obtained recent attention as individual white matter tracts have more clinical significance. In this abstract, we further explored an MTTA technique capable of restoring the FA values of the targeted tract along its path while correcting the bias in single tensor FA. Specifically, we directly tested MTTA with in vivo diffusion MRI acquired in routine clinical research and proposed weighted FA at the crossing-fiber voxels as an unbiased anisotropy metric.

3191.   92 TBSS May Be Sub-Optimal for Detection of DTI Parameter Changes in Crossing Fiber Regions
Vincent J. Schmithorst1, Jessica L. Wisnowski1, and Ashok Panigrahy1
1Radiology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, United States

In crossing fiber regions, the Tract-Based Spatial Statistics (TBSS) algorithm for spatial normalization may be sub-optimal, as these voxels might not be projected onto the skeleton and thus excluded from analysis. We investigated the relation of functional network integration to DTI parameters and compared TBSS to an alternative technique involving normalization to a white matter template. While no region with a significant correlation was found with TBSS, a crossing-fiber region in the right hemisphere was detected via the alternative technique. Results suggest that normalization to a white matter template should be considered as a complementary analysis strategy to TBSS.

3192.   93 Motion Correction in Diffusion Spectrum Imaging Using Simulated Diffusion Images at Multiple B Bands
Kwan-Jin Jung1, Nidhi Kohli2, Fang-Cheng Yeh3, Timothy Keller4, and Tiejun Zhao5
1Psychology, Carnegie Mellon University, Pittsburgh, PA, United States, 2Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States, 3Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States, 4Psychology, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States, 5MR R&D Collaborations, Siemens Medical Solutions USA, Pittsburgh, Pennsylvania, United States

The motion in diffusion imaging was more accurately estimated using simulated diffusion images rather than the b=0 images because the simulated diffusion images had the same contrast as the diffusion images. For diffusion imaging with a single shell b this method has been confirmed to be effective without extensive iteration even for a large amount of deliberate motion. Furthermore, this method has been extended to account for multiple exponential diffusion weighting in diffusion spectrum imaging where the b value ranges widely.

3193.   94 Performance Evaluation of Various Numerical Algorithms for a Multi-Compartmental IVIM-Model
Burkhard Mädler1 and Volker A. Coenen2
1Neurosurgery, University Bonn, Medical Centre, Bonn, Germany, 2Divison Stereotaxy and MR-based OR Techniques, University Bonn - Medical Centre, Bonn, Germany

Diffusion-weighted MRI (DWI) is a non-invasive imaging technique that detects thermally driven, random motion of water molecules in living tissue and is able to characterize its interaction with cell membranes, macromolecules and potential diffusion barriers. Le-Bihan proposed a bi-exponential model to separate intra- and extracellular diffusion from incoherent motion of water molecules within randomly oriented capillaries – IVIM. The presence of noise may substantially affect IVIM parameter estimation. Mathematical inversion of multi-exponential processes like water diffusion in living tissue is a strongly ill-posed problem and the necessity for a large number of signal points and SNR is imminent for a reliable separation of more than one exponential time constant. The evaluation of current fitting modalities for IVIM data and investigating their limitations in relation to SNR and number of b-values is therefore prudent.

95 Information Extraction from Raw DTI Data Using Texture Based Analysis: A Preliminary Study of Classification and Regression
Che-Wei Chang1,2, Chien-Chang Ho1, and Jyh-Horng Chen1,2
1Electrical Engineering, National Taiwan University, Taipei, Taiwan, 2Interdisciplinary MRI/MRS Lab, National Taiwan University, Taipei, Taiwan

This study presents a texture based analysis, Local Binary Pattern on Three Orthogonal Planes (LBP-TOP), to extract effective features from raw DTI data. Examples of sex classification and age estimation were used to demonstrate the performance of this method. A total 204 subject downloaded from NKI/Rockland Samples were used to evaluate those approaches. Our results show that the best sex classification accuracy is 0.81, and the best age estimation mean average error is 6.32 years. We demonstrated that LBP-TOP is capable of extracting effective information from DTI and could be a good candidate for classifying or evaluating neurological diseases based on raw DTI data.

3195.   96 High-Spatial and High-Angular Resolution Diffusion Imaging with a Fragmented Acquisition Scheme
Sjoerd B. Vos1,2, Murat Aksoy2, Julian R. Maclaren2, Zhaoying Han2, Samantha J. Holdsworth2, Alexander Brost2, Christoph Seeger2,3, Alexander Leemans1, and Roland Bammer2
1Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands, 2Center for Quantitative Neuroimaging, Department of Radiology, Stanford University, Stanford, California, United States, 3Pattern Recognition Lab, Department of Computer Science, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany

Recent 3D DWI pulse sequences can achieve resolutions up to 1mm isotropic, at the expense of longer acquisition times per volume. To acquire HARDI data with these high resolutions, the large number of diffusion directions required for HARDI can be spread out over different imaging sessions. We present a validated approach to acquire high-angular and high-spatial resolution diffusion imaging over different sessions, suggesting a ‘head holder’ that fits tightly around the subject’s head and in the coil. Accurate subject repositioning is ensured in each session, resulting in seamless fusion of data from different sessions.


Monday, 22 April 2013 (15:15-16:15) Exhibition Hall
Diffusion MR Artefacts & Data Quality

  Computer #  
3196.   73 Retrospective Correction of Physiological Noise in DTI Using Peripheral Measurements in an Extended Tensor Model Framework
Siawoosh Mohammadi1, Chloe Hutton1, Zoltan Nagy1, Oliver Josephs1, and Nikolaus Weiskopf1
1Wellcome Trust Centre for Neuroimaging at UCL, ION UCL, UCL, London, London, United Kingdom

One important and still unresolved artefact in diffusion MRI is physiological movement, which can lead to severe bias in the signal. We developed an easy-to-implement extension of the original diffusion tensor model to account for physiological noise using measures of peripheral physiology (pulse and respiration), the so-called extended tensor model. We tested the performance of four different extended tensor models with different physiological noise regressors on non-gated and gated diffusion tensor imaging data, and compared it to an established data-driven robust fitting method. We showed that the framework of the extended tensor model facilitates investigation into physiological noise in DTI.

3197.   74 Inter-Vendor Variability in Apparent Diffusion Coefficient Values -permission withheld
Michael A. Levine1, Pavlina Polaskova1, Sara Maria Sprinkhuizen1, Steven M. Stufflebeam1, Bruce R. Rosen1, Jayashree Kalpathy-Cramer1, and Elizabeth R. Gerstner1
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States

Fifteen glioblastoma patients treated with combination cediranib and cilengitide were enrolled in a correlative magnetic resonance imaging substudy. Ventricular apparent diffusion coefficient values were found to be statistically different across vendors. Multi-center clinical trials should be particularly careful to ensure that results acquired from different vendors are comparable.

3198.   75 How Is the Fractional Anisotropy Affected by Frequency-Dependent Changes to the Eigenvalues of the Apparent Diffusion Tensor Measured with Oscillating-Gradient Spin-Echo Diffusion Tensor Imaging?
Jeff Kershaw1,2, Christoph Leuze3, Ichio Aoki1, Takayuki Obata4, Iwao Kanno1, Hiroshi Ito1, Yuki Yamaguchi2, and Hiroshi Handa2
1Molecular Imaging Centre, National Institute of Radiological Sciences, Chiba, Japan, 2School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan, 3Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, 4Research Centre for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan

Recent work applying the oscillating-gradient spin-echo sequence to diffusion-tensor imaging of in vivo rat brain has found substantial, approximately linear changes with frequency to the eigenvalues (EVs) of the apparent diffusion tensor and to the fractional isotropy (FA). While the FA is a well known function of the EVs, it is not immediately clear how the behaviour of the EVs relates to the trends in the FA. This work investigates how the FA is affected by changes to the EVs.

3199.   76 SNR Dependence of Mean Kurtosis and How to Correct It
Elodie André1, Christophe Phillips1,2, Ezequiel Farrher3, Ivan I. Maximov4, Farida Grinberg3, Nadim Jon Shah4,5, and Evelyne Balteau1
1Cyclotron research center, University of Liège, Liège, Belgium, 2Department of Electrical Engineering and Computer Science, University of Liège, Liège, Belgium, 3Institute of Neuroscience and Medicine - 4, Forschungszentrum Juelich, Juelich, Germany, 4Institute of Neuroscience and Medicine - 4, Forschungszentrum Juelich GmbH, Juelich, Germany, 5Department of Neurology, Faculty of Medicine, RWTH Aachen University, JARA, Aachen, Germany

The use of high b-values in diffusion kurtosis imaging makes the derived parameters very sensitive to low signal to noise. Here we show the dependence of mean kurtosis on SNR and demonstrate that noise correction is a necessary step, leading to more reproducible metrics.

3200.   77 Bias in Diffusion Tensor Tissue Integrity Measures Due to Sum of Squares Reconstruction: Characterization and Retrospective Correction
Ken E. Sakaie1, Kecheng Liu2, and Mark J. Lowe1
1Imaging Institute, The Cleveland Clinic, Cleveland, OH, United States, 2Siemens Medical Solutions USA, Inc, Malvern, PA, United States

Diffusion tensor imaging provides quantitative measures of tissue integrity that can be biased by the properties of the noise distribution. Sum of squares is commonly used for reconstructing multi-coil imaging data and exhibits Rician bias for signals near noise floor, leading to substantial bias in diffusivity values. Here, we quantify the bias and demonstrate that a simple but effective correction that can be applied retrospectively.

3201.   78 The Influence of Imaging Gradients in the Analysis of Diffusion Signals from Pulsed and Oscillating Gradient Sequences
Damien McHugh1,2, Penny L. Hubbard1,2, Geoffrey Parker1,2, and Josephine H. Naish1,2
1Centre for Imaging Sciences, University of Manchester, Manchester, United Kingdom, 2The University of Manchester Biomedical Imaging Institute, Manchester, United Kingdom

The effect that imaging gradients have on b-values in oscillating and pulsed gradient diffusion sequences are compared. The impact this has on parameters obtained from model fitting is then evaluated using synthetic data from three models: monoexponential decay, biexponential decay, and the kurtosis model. It is shown that the diffusion-weighting introduced by imaging gradients in oscillating gradient sequences has little impact on parameter estimates for each model. Conversely, ignoring the influence of imaging gradients in pulsed gradient sequences is shown to lead to significant errors in fitted parameters, especially for the biexponential model.

3202.   79 Gradient Nonlinearity Correction to Improve ADC Accuracy and Standardization in Breast Cancer Clinical Trials
David C. Newitt1, Ek T. Tan2, Thomas L. Chenevert3, Lisa J. Wilmes1, Suchandrima Banerjee4, Luca Marinelli2, and Nola M. Hylton5
1Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States, 2Diagnostics and Biomedical Technologies, GE Global Research, Niskayuna, New York, United States, 3Radiology – MRI, University of Michigan, Ann Arbor, Michigan, United States, 4Applied Science Lab, GE Healthcare, Menlo Park, California, United States, 5Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States

Gradient nonlinearity (GN) is a significant source of error for quantitative diffusion MRI, and the extent of GN varies with the scanner used. This confounds results from multi-center and longitudinal studies required in clinical trials. GN effects are of particular concern in breast imaging, where the anatomy has large offsets from magnet isocenter. Retrospective GN correction (GNC) was evaluated in a multi-center setting with phantoms and in normal and breast cancer subjects. GNC significantly reduced the spatial-dependence of ADC values and improved quantitative accuracy of ADC, which could in turn improve the sensitivity of cancer-detection and cancer-monitoring in diffusion MRI.

3203.   80 Improved Accuracy of Motion and Affine Eddy Current Distortion Correction in High B-Value Diffusion Weighted Imaging Using Brain Mask Based Weighting Functions
Christopher Leslie Adamson1, Richard Beare1, Deanne Thompson1, and Marc Seal1
1Developmental Imaging, Murdoch Childrens Research Institute, Parkville, VIC, Australia

We present an improved method for correction of affine distortions in high b-value diffusion weighted imaging due to eddy currents and subject movement. We show that our method improves the alignment and scaling of the registration results. The improved registration has implications for DTI and tractography applications.

3204.   81 Joint Estimation Based Phase Error Correction in Multi-Shot Spiral Diffusion Weighted Imaging
Pan Su1, Xiaodong Ma2, Wenchuan Wu2, and Hua Guo2
1School of Electronic and Information Engineering, Beihang University, Beijing, China, 2Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China

Phase inconsistencies among different shots in multi-shot diffusion imaging causes artifacts in final images. Oversampling in k-space center is thus required to remove these errors, however, it inevitably lengthens the readout window and introduces further blurring artifacts. In this study, a new method is proposed to estimate object function and motion-induced phase map in muti-shot spiral DWI jointly, and is validated by the simulation results. Our proof-of-concept work demonstrates that this method estimates the desired artifact-free image more accurately than self-navigator based technique when navigator information is limited, which has potential utilization in high resolution diffusion imaging.

3205.   82 Fast Automatic Spike Artifact Assessment in DTI Data for Monitoring Possible Hardware Issues
Daniel Güllmar1, Stefan Kämmer2, and Jürgen R. Reichenbach1
1Medical Physics Group, Institute of Diagnostic and Interventional Radiology I, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany,2Faculty of Computer Science and Automation, Technical University Ilmenau, Ilmenau, Germany

A simple and fast algorithm for assessment of DTI spike noise based on the background signal was implemented and applied to more than 1500 data sets. The determined quality measure was used as indicator for hardware issues and correlated to recorded incidents in the past. We found that all relevant hardware problems which forward spike noise had have been detected using this approach.

3206.   83 in-vivo High Resolution Diffusion Tensor Imaging of the Human Heart at 3T: Fat Suppression in the Presence of B0 Field Inhomogeneities
Jack Harmer1, Christian T. Stoeck2, Rachel W. Chan3, Nicolas Toussaint1, Constantin Von Deuster2, David Atkinson3, and Sebastian Kozerke1,2
1Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, United Kingdom, 2Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, 3Centre for Medical Imaging, University College London, London, United Kingdom

In recent work diffusion acquisition schemes that employ stimulated echoes (STE) have been used to allow diffusion tensor imaging of the beating heart. Higher order localized image based shimming can partially compensate for the increased field inhomogeneity at high field strength but, at the same time, compromises the effectiveness of fat saturation techniques such as SPIR across the entire field-of-view. We present a dual navigated STE sequence with Slice Selective Gradient Reversal (SSGR) applied to the second and third RF pulses in order to suppress the fat signal in in-vivo data of the human heart at 3T.

3207.   84 A Novel Method for Determining the Reliability of Diffusion-Weighted Imaging Data
Karl G. Helmer1, Ming-Chung Chou2, Ronny I. Preciado3, Allen Song4, Jessica Turner5, Barjor Gimi6, and Susumu Mori7,8
1Radiology, Massachusetts General Hospital, Charlestown, MA, United States, 2Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan, 3Massachusetts General Hospital, Charlestown, MA, United States, 4Radiology, Duke University, Durham, NC, United States,5Translational Neuroscience, The Mind Research Network, Albuquerque, NM, United States, 6Radiology and Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States, 7Radiology, Johns Hopkins School of Medicine, Baltimore, MD, United States, 8Kennedy Kreiger Institute, Baltimore, MD, United States

We report on a method using histogram-similarity measures to establish normative data which can be used in the “calibration” of diffusion-weighted imaging data collected at a single or multiple sites. This method can be used to quantitatively determine the quality of new data acquired over time by comparing it to the normative data. We have calculated histogram similarity using different metric types, both within and between sites and have shown that these metrics are sensitive measures for both fractional anisotropy (FA) and mean diffusivity (MD). Statistical significance of the results was determined using simulations of two different histogram distributions.

3208.   85 Feasibility of Ultra-Short EPI Navigator for DTI Motion Detection
Hu Cheng1
1Indiana University, Bloomington, IN, United States

Information of head rotation during DTI data acquisition is critical for reliable fiber tracking. However, the information can be erroneously extracted by decomposing the affine matrix from image registration because of image distortions induced by Eddy current. In this work, we examined the feasibility of retrospective motion correction by using an ultra-short EPI navigator via GRAPPA operators. Based on the simulated data from real EPI scans, it is possible to use only three K-space lines to obtain accurate between-volume head motion. Our results are encouraging for implementing this technique in DTI pulse sequence.

3209.   86 Relaxation Corrected Diffusion Weighted Imaging
Daniel Guo Quae Chong1
1Dept. of Diagnostic, Interventional and Pediatric Radiology (DIPR), Inselspital, Bern, Bern, Switzerland

DWI is inherently T2 weighted and can caused problem such as T2 shine through. Relax DWI is a novel sampling scheme that can estimate T2 map with only one additional b value measurement compare to normal DWI. Relax DWI uses minimum TE for each b values. Additional data point at low b value and long TE assist in fit stability. T2 shine through can be corrected by remove T2 component from DWI at different b values. Examples like abdominal organs and peritoneal metastasis are shown.

3210.   87 Prospective Correction Rigid-Body Motion-Induced Phase for Diffusion-Weighted SSFP Imaging
Rafael O'Halloran1, Anh Tu Van1, Eric Aboussouan1, Murat Aksoy1, and Roland Bammer1
1Radiology, Stanford University, Stanford, CA, United States

Diffusion-weighted SSFP Imaging is an alternative to single-shot spin echo EPI that can provide high resolution (<1.5mm isotropic) DWI and DTI images. Because Diffusion-weighted SSFP is a multi-shot technique, motion-induced phase errors can cause reconstruction issues and most critically, can cause loss of steady-state phase coherence. Phase navigation has been shown to help retrospectively to mitigate loss of image magnitude but errors remain because phase errors accrued during a particular TR propagate into all coherence pathways derived from the transverse phase states of that TR. This ultimately results in disruption of the steady state. In this work phase navigation is used to prospectively correct the rigid-body component of motion-induced phase and is shown to improve signal magnitude in a phantom-based feasibility study.

3211.   88 Impact of Accuracy and Reliability of Diffusivity in Assessing Acute Ischemic Stroke -permission withheld
Venkata Veerendranadh Chebrolu1, Dattesh D. Shanbhag1, Ek Tsoon Tan2, Patrice Hervo3, Marc-Antoine Labeyrie4, Catherine Oppenheim4,5, and Rakesh Mullick1
1Medical Image Analysis Lab, GE Global Research, Bangalore, Karnataka, India, 2GE Global Research, Niskayuna, NY, India, 3GE Healthcare, Buc, France,4Departments of Radiology and Neurology, Centre Hospitalier, Sainte-Anne, Paris, France, 5Université Paris Descartes, Paris, France

The b-factor used for DWI imaging could vary due to factors such as gradient non-linearity and concomitant field effects. These system imperfections may differ between different vendors and MRI systems. This variation would impact multi-center studies evaluating the efficacy of the PDM criteria for thrombolysis treatment decision. In this work we demonstrate that in presence of b-factor variability a joint DWI and ADC based method may offer more robust perfusion-diffusion mismatch assessment compared to ADC alone based DWI lesion segmentation method.

3212.   89 Combined Eddy-Current and EPI-PSF-Based Distortion Corrections in Quantification of DW EPI at UHF
Oleg Posnansky1, Myung-Ho In1, and Oliver Speck1
1BMMR, IEP, Otto-von-Guericke University, Magdeburg, SA, Germany

Single-shot spin-echo echo-planar imaging allows for very fast signal acquisition and is frequently used in diffusion-weighting (DW) MRI. However, it is prone to severe distortions due to local variations in the static magnetic field, eddy currents induced by the DW gradients, susceptibility, and chemical shift, especially at ultra-high magnetic field. Geometric incongruence in DW images may impose significant errors in calculations of diffusion tensors and their derived metrics. We demonstrate that these imperfections can be corrected effectively by a combination of eddy-current correction and improved point-spread function mapping.

3213.   90 Comparison of Image Quality Control Tools for Diffusion Tensor Images
Bilan Liu1, Tong Zhu2, and Jianhui Zhong2
1Electrical and Computer Engineering, University of Rochester, Rochester, NY, United States, 2Imaging Sciences, University of Rochester, Rochester, NY, United States

Diffusion tensor imaging (DTI) is susceptible to numerous artifacts. Therefore the Quality control (QC) of the Diffusion tensor images is critical for image interpretation and diagnostic accuracy. The goal of this study is to develop an experimental protocol to help choose between existing QC tools by analyzing the precision and accuracy of fractional anisotropy (FA), mean diffusivity (MD) calculated by those tools in the presence of major DTI-specific artifacts. Both simulation data obtained using Monte Carlo simulation and human in vivo data were used to help assess the effectiveness of those QC tools.

3214.   91 Clinical Diffusion Imaging: Can We Still Use Corrupted Images in Voxelwise Analysis?
Ivan I. Maximov1, Farida Grinberg2, Irene Neuner1,3, and Nadim Jon Shah1,4
1Institute of Neuroscience and Medicine 4, Forschungszentrum Juelich GmbH, Juelich, Germany, 2Institute of Neuroscience and Medicine 4, Forschungszentrum Juelich, Juelich, Germany, 3Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, Aachen, Germany,4Department of Neurology, RWTH Aachen University, Aachen, Germany

Clinical diffusion imaging frequently suffers from multiple artefacts. As a consequence, many corrupted datasets cannot be used in further analysis and/or medical treatments. We have developed a robust post-processing framework that allows one to recover the degraded datasets and to return them to use. In order to demonstrate the advantages of the developed framework, the results obtained by the robust approach with other post-processing algorithms are compared. We show the benefits of the robust post-processing framework using voxelwise analysis by TBSS software from FSL package.

3215.   92 Quantitative Analysis of Directional Bias Imposed on Primary Eigenvector Estimations in DTI When Gradient Table Correction Is Neglected
Ali Ersoz1, Volkan Emre Arpinar2, and L. Tugan Muftuler2,3
1Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States, 2Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, United States, 3Center for Imaging Research, Medical College of Wisconsin, Milwaukee, WI, United States

We conducted a quantitative analysis of directional bias imposed on primary eigenvector (PE) estimations in DTI when gradient table is not reoriented after motion correction. We compared this bias with the inherent uncertainty in the estimation of orientation distribution functions. We found that 90% percent of the voxels in cingulum and CST tracts had substantially smaller directional adjustments on the PE than the uncertainty in their estimations. We also demonstrated that this directional bias might accumulate along the fiber tract and lead to inaccurate fiber tracking. The findings were validated using simulations.

3216.   93 Gradient Nonlinearity Effects of Diffusion Weighted Imaging in a Dedicated Head-Only MRI System
Ek T. Tan1, Seung-Kyun Lee1, Jean-Baptiste Mathieu1, Venkata Veerendranadh Chebrolu2, Dattesh D. Shanbhag2, Matthew A. Bernstein3, John Huston III3, Luca Marinelli1, and John F. Schenck1
1Diagnostics and Biomedical Technologies, GE Global Research, Niskayuna, NY, United States, 2Diagnostics and Biomedical Technologies, GE Global Research, Bangalore, India, 3Radiology, Mayo Clinic, Rochester, MN, United States

A head-only MRI system can have cost and performance advantages, especially in diffusion imaging. However, a dedicated head-only gradient coil tends to have a greater gradient field nonlinearity (GN) compared to a conventional whole-body gradient coil optimized for body imaging. This nonlinearity results in a larger spatial variation of the diffusion-encoding b-value. Diffusion imaging using a dedicated, head-only gradient coil without nonlinearity correction was found to produce significant, spatially-varying b-values that would result in highly inaccurate diffusion-weighted images, ADC and FA. However, the inaccuracies were correctable with GN correction employing 5th-order spherical harmonics. These results will be of interest in quantitative stroke and oncology imaging.

3217.   94 Practical Aspects of Correcting ADC Bias Due to Gradient Nonlinearity in Media of Arbitrary Anisotropy
Dariya I. Malyarenko1, Brian D. Ross1, and Thomas L. Chenevert1
1Radiology - MRI, University of Michigan, Ann Arbor, Michigan, United States

Relatively large ADC bias error, well exceeding measurement noise, can be observed for anatomical regions imaged distant from magnet isocenter. Gradient nonlinearity is a main source of bias. Our previously-described approach allowed substantial reduction of spatial ADC bias for media of arbitrary anisotropy using DWI encoding along any three orthogonal directions. This work focuses on practical aspects of ADC correction implementation via system nonlinearity tensor for derivation of correctors applicable to DWI or b-map generation. Correction performance was evaluated for isotropic and anisotropic media.

3218.   95 Effects of Noise Estimation Error on the Accuracy and Precision of Maximum Likelihood Estimation of Apparent Diffusion Coefficient
Jing Yuan1, Qinwei Zhang1, David Ka Wai Yeung1, Anil T. Ahuja1, and Ann D. King1
1Department of Imaging and Interventional Radiology, Chinese University of Hong Kong, Shatin, NT, Hong Kong

Maximum likelihood estimation (MLE) is preferable as an unbiased estimator compared to least-squares estimation (LSE) due to the Rician noise distribution of magnitude MR image. Accurate noise estimation is essential for MLE that affects accuracy and precision of MLE, but is often hampered by many factors in practice. We investigate the effects of erroneous noise estimation on ADC estimation by MLE through simulation and ADC mapping of clinical DWI images. Results show that MLE accuracy and precision are significantly reduced by noise estimation error at low signal-to-noise ratios (SNRs), but exhibit fairly good robustness to such errors at high SNRs>10.

3219.   96 A Simple and Efficient Method for Acceleration and Denoising of Multi-Contrast Diffusion Data: Application to Q-Space and HARDI
Ana-Maria Oros-Peusquens1 and Nadim Jon Shah1,2
1INM-4, Research Centre Jülich, Jülich, Germany, 2Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany

We present a method combining acceleration of multi-contrast diffusion data using UNFOLD with denoising based on singular value decomposition (SVD). UNFOLD is ideally suited for acceleration of q-space acquisition because q-space information is extracted from the Fourier transform of the q-dependent diffusion signal. The information is largely contained in the q-space centre, a region unaffected by aliasing at moderate UNFOLD acceleration (2-4). Multi-direction HARDI signal also has Fourier components in a restricted interval and is thus very well suited for UNFOLD acceleration. SVD denoising works extremely well for q-space data and also, but less spectacularly, for quantitative information obtained with HARDI. In conclusion, acceleration and denoising of q-space and HARDI data is demonstrated, using simple methods with numerically undemanding reconstruction. The same method should work well for combinations of q-space and HARDI, such as diffusion spectrum imaging (DSI).