ISMRM 24th Annual Meeting & Exhibition • 07-13 May 2016 • Singapore

Scientific Session: Neurovascular Disease & Stroke

Wednesday, May 11, 2016
Hall 606
10:00 - 12:00
Moderators: Rao Gullapalli, Masaaki Hori

Transient Oxygen Extraction Fraction as a Measure of Cerebrovascular Reserve - Permission Withheld
Charles G Cantrell1, Parmede Vakil1,2, Donald R Cantrell3, Yong Jeong1, Sameer A Ansari3, and Timothy J Carroll1,3
1Biomedical Engineering, Northwestern, Chicago, IL, United States, 2College of Medicine, University of Illinois, Chicago, IL, United States, 3Radiology, Northwestern, Chicago, IL, United States
We have found that MR-PARSE has detectable sensitivity to frequency shifts induced by transient alterations in de-oxyhemoglobin through the cardiac cycle.  Our initial studies have shown, through the use of ICA, a statistically significant hemispheric difference between healthy and compromised regions.  Our approach to quantifying cerebrovascular reactivity represents a new and simple, non contrast approach to stratifying patients toward therapies to prevent stroke.

Ex-vivo Quantitative Imaging and Qualitative Plaque Type Classification of Intracranial Atherosclerotic Plaque using High Resolution MRI
Yuanliang Jiang1, Chengcheng Zhu2, Andrew J Degnan3, Wenjia Peng1, Luguang Chen1, Xinrui Wang1, Qi Liu1, Yang Wang4, Zhenzhen Xiang4, Zhongzhao Teng5, David Saloner2, and Jianping Lu1
1Radiology, Changhai Hospital, Shanghai, China, People's Republic of, 2Radiology, University of California, San Francisco, San Francisco, CA, United States, 3Radilogy, University of Pittsburgh, Pittsburgh, PA, United States, 4Pathology, Changhai Hospital, Shanghai, China, People's Republic of, 5Radiology, University of Cambridge, Cambridge, United Kingdom
The first ex vivo measurement of T1, T2, and T2* relaxation times of intracranial plaque components at 3T is reported. The ability of multi-contrast MRI to characterize plaque type was evaluated with histological validation. Plaque components could be differentiated based on relaxation times. Specifically, lipid core had significantly lower T2 values than fibrous cap. MRI and histology correlation was consistent across specimens and locations, and MRI showed a high sensitivity and specificity for identifying plaque features previously associated with high-risk. Therefore, MRI has the potential to characterize intracranial plaque composition and improve patient risk stratification.  

Acceleration-selective Arterial Spin Labeling (AccASL) MR Angiography for Visualization of Distal Cerebral Arteries in Moyamoya Disease
Osamu Togao1, Akio Hiwatashi1, Makoto Obara2, Koji Yamashita1, Kazufumi Kikuchi1, and Hiroshi Honda1
1Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan, 2Philips Electronics Japan, Tokyo, Japan
In this study, we demonstrated the utility of intracranial MR angiography (MRA) using acceleration-selective arterial spin labeling (AccASL) technique in Moyamoya disease. The AccASL-MRA markedly improved the visualization of arteries distal to the steno-occlusive site reflecting collateral flow via LMA in Moyamoya disease in comparison with time-of-flight (TOF)-MRA.

Serial Quantification of Brain Oxygenation using Streamlined-qBOLD in Acute Stroke Patients
Alan J Stone1, George WJ Harston2, Davide Carone2, Mmua Ngwako2, Radim Licenik2, James Kennedy 2, and Nicholas P Blockley1
1FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom, 2Acute Stroke Programme, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
Streamlined-qBOLD is applied to an exploratory cohort of acute stroke patients in a serial imaging study to map brain oxygen metabolism. Quantitative brain oxygenation parameters are demonstrated to vary between regions with different tissue outcomes and this imaging approach is shown to have the potential to refine the identification of the ischemic penumbra.

Relationship between Cerebrovascular Reserve and Brain Temperature following Acetazolamide Challenge in Patients with Chronic Steno-Occlusive Disease - Permission Withheld
Seena Dehkharghani1, Candace C. Fleischer2, Deqiang Qiu1, Sang-Eon Park2, Junjie Wu1, and Fadi Nahab3
1Radiology and Imaging Sciences, Emory University, Atlanta, GA, United States, 2Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, United States, 3Neurology, Emory University, Atlanta, GA, United States
Methods for characterizing misery perfusion to predict stroke are largely limited to positron emission tomography, which suffers from high radiation exposure. Magnetic resonance imaging (MRI) and spectroscopy (MRS) offer non-invasive alternatives to explore cerebral hemodynamics and brain temperature regulation, a poorly understood physiologic variable at the intersection of perfusion and metabolism. We detail the first reported use of MRI/MRS to relate cerebrovascular reserve with temperature in patients following acetazolamide challenge, observing significant correlation between temperature changes and cerebrovascular reserve. These findings will be used to inform future MRI studies of perfusion and brain temperature among patients with chronic steno-occlusive disease.

Stroke Volume Evolution Following Endovascular Therapy on DWI and FLAIR
Christian Federau1, Soren Christensen1, Michael Mlynash1, Jenny Tsai1, Sun Kim1, Greg Zaharchuk1, Matus Straka1, Nishant Mishra1, Maarten Lansberg1, and Greg Albers1
1Stanford University, Stanford, CA, United States
We studied the evolution of the infarct volume between an early post-revascularization scan (within 24 h of symptom onset) and day 5 in patients of the CRISP and DEFUSE 2 cohort studies.  On the early post-revascularization scan, FLAIR lesions were smaller compared to DWI, but were larger at day 5. The early post-revascularization stroke volume on DWI, compared to FLAIR, was closer, and correlated better with the day 5 DWI and FLAIR lesion volumes. Together, our findings suggest that DWI is a better early surrogate marker of stroke volume. 

Quantitative Susceptibility Mapping (QSM) based Cerebral Metabolic Rate of Oxygen (CMRO2) Mapping: Eliminating Blood Flow Challenge with Minimal Local Variance (MLV)
Jingwei Zhang1,2, Dong Zhou2, Sarah Eskreis-Winkler2, Thanh Nguyen2, Pascal Spincemaille2, Ajay Gupta2, and Yi Wang1,2
1Biomedical Engineering, Cornell University, New York, NY, United States, 2Radiology, Weill Cornell Medical College, New York, NY, United States
We propose a cerebral metabolic rate of oxygen consumption (CMRO2) mapping method without blood flow challenge using quantitative susceptibility mapping, cerebral blood flow and a regularization of minimal local variance (MLV) within the same type of tissue. Getting rid of blood flow challenge would vastly increase the clinical utility of MRI CMRO2. The MNV CMRO2 maps were very similar to CMRO2 maps using caffeine as challenge, with no significant bias in value. 

Flow dynamics in a 3D printed brain aneurysm model assessed by magnetic particle imaging, magnetic resonance imaging and dynamic subtraction angiography
Jan Sedlacik1, Andreas M. Frölich1, Johanna Spallek2, Nils D. Forkert3, Tobias D. Faizy1, Franziska Werner4,5, Tobias Knopp4,5, Dieter Krause2, Jens Fiehler1, and Jan-Hendrik Buhk1
1Neuroradiology, UKE, Hamburg, Germany, 2Product Development and Mechanical Engineering Design, TUHH, Hamburg, Germany, 3University of Calgary, Calgary, AB, Canada, 4Biomedical Imaging, UKE, Hamburg, Germany, 5Biomedical Imaging, TUHH, Hamburg, Germany
Magnetic particle imaging (MPI) was compared with dynamic magnetic resonance imaging (MRI) and dynamic subtraction angiography (DSA) in a realistic 3D printed aneurysm model. All three methods clearly depicted a distinct pulsatile flow pattern and a delayed contrast agent outflow from the aneurysm. Despite the disadvantages of a much lower temporal resolution of the dynamic MRI and the 2D projection of the DSA, all three methods are valid tools for characterizing the hemodynamics of aneurysms. Especially the radiation free, 3D, high temporal resolution MPI method seems to be a very promising tool for imaging and characterization of hemodynamics.

Microstructure Parameters in Acute Stroke: A Bayesian Approach to diffusion-weighted MRI
Elias Kellner1, Karl Egger2, Valerij G Kiselev2, Horst Urbach2, and Marco Reisert1
1Department of Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany, 2Department of Neuroradiology, University Medical Center Freiburg, Freiburg, Germany
In a recent study, we proposed a method for fast estimation of microstructural tissue parameters such as intra/extraaxonal volume fraction and diffusivities based on a Bayesian approach and machine learning. In this study, we report the application to cases of acute ischemic stroke. We show that the parameters are able to outline the infarct core qualitatively better than standard DTI. The results are in line with the currently accepted picture of axonal beading.

Chronological evaluation of Cerebral Hemodynamics by Dynamic Susceptibility Contrast Magnetic Resonance Imaging after Indirect Bypass Surgery for Moyamoya Disease
Yosuke Ishii1,2, Tadashi Nariai1, Yoji Tanaka1, HIroshi Aihara2, Yoshio Suyama2, Shinichi Wakabayashi2, and Taketoshi Maehara1
1Neurosurgery, Tokyo Medial and Dental University, Tokyo, Japan, 2Neurosurgery, Suiseikai Kajikawa Hospital, Hiroshima, Japan
We used dynamic susceptibility contrast (DSC)-MRI to evaluate the chronological changes in hemodynamics after indirect bypass surgery for moyamoya disease. Twenty five patients who underwent indirect bypass surgery and repeated DSC–MRI measurement within the first 6 postoperative months were included. We analyzed mean transit time (MTT) delay using the cerebellum as control. Mean MTT delay in the anterior circulation area gradually decreased soon after surgery and stabilized after 3 postoperative months. Postoperative MTT delay values were significantly decreased compared with preoperative values from 1 to 2 weeks onwards. These results suggested DSC–MRI detected angiogenesis during the early postoperative stages.

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