Joint Annual Meeting ISMRM-ESMRMB 2014 10-16 May 2014 Milan, Italy

Stroke: MRA & Vessel Wall Imaging

Wednesday 14 May 2014
Silver  10:00 - 12:00 Moderators: Michael Markl, Ph.D., David Saloner, Ph.D.

10:00 0512.   
Quantitative Vessel-Encoded Arterial Spin Labeling Reveals Collateral Blood Flow in Hyper-Acute Stroke Patients
Thomas W Okell1, George WJ Harston2, Michael A Chappell3, Fintan Sheerin4, Martino Cellerini4, Stephen J Payne3, James Kennedy5, and Peter Jezzard1
1FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, Oxfordshire, United Kingdom, 2Nuffield Department of Medicine, University of Oxford, Oxford, Oxfordshire, United Kingdom, 3IBME, Department of Engineering Sciences, University of Oxford, Oxford, Oxfordshire, United Kingdom, 4Department of Neuroradiology, Oxford University Hospitals NHS Trust, Oxford, Oxfordshire, United Kingdom, 5Radcliffe Department of Medicine, University of Oxford, Oxford, Oxfordshire, United Kingdom

Multi-postlabeling delay vessel-encoded arterial spin labeling is capable of generating artery specific quantitative maps of cerebral blood flow and bolus arrival time non-invasively and without contrast agent. This method was applied to serially study hyper-acute stroke patients. Changes in the vascular territories over time were observed, with collateral flow appearing to spare tissue from infarction. Significant delays to blood arrival were measured in regions around the perfusion deficit compared to the contralateral side. This technique shows promise for diagnosis, prognosis and understanding the pathophysiology of acute stroke.

10:12 0513.   
Robust Whole-Brain Blood Tracking from 4D Flow using Displacement Corrected Probabilistic Streamlines
Michael Loecher1, Kevin Johnson1, Patrick Turski2, and Oliver Wieben1,2
1Medical Physics, University of Wisconsin Madison, Madison, Wisconsin, United States, 2Radiology, University of Wisconsin Madison, Madison, Wisconsin, United States

A novel algorithm is presented for tracking blood flow through the whole brain neurovasculature using 4D flow imaging data. The method incorporates probabilistic streamlines, displacement corrections, and additional fluid constraints. The algorithm was tested in 5 patients with aneurysms or arteriovenous malformations (AVMs). Good agreement is seen when compared to pseudo-continuous arterial spin labeling (PCASL). The technique also allows for retrospective seed placement to selectively measure downstream vessels, or evaluate AVM feeding and draining.

10:24 0514.   
Hemodynamic Evaluation of Cerebral Arteriovenous Malformations with Combined 4D Flow and Perfusion MRI
Can Wu1, Timothy Carroll1,2, Sameer Ansari2,3, Amir Honarmand2,3, Parmede Vakil2, Michael Hurley2,3, Bernard Bendok2,3, James Carr2, and Michael Markl1,2
1Biomedical Engineering, Northwestern University, Chicago, IL, United States, 2Radiology, Northwestern University, Chicago, IL, United States,3Neurological Surgery, Northwestern University, Chicago, IL, United States

4D flow and perfusion MRI were combined to quantitatively evaluate macro- and microvascular hemodynamics in cerebral arteriovenous malformations (AVMs), investigate the influence of Spetzler-Martin grade on AVM hemodynamics, and identify potential relationships between changes in macro- and microvascular flow and perfusion. The results demonstrated the influence of Spetzler-Martin grade on AVM hemodynamics in the feeding arteries, draining veins, and the straight sinus. In addition, we could identify significant relationships between large vessel flow and perfusion ratios. These findings demonstrate the potential of our imaging protocol for the comprehensive characterization of the impact of AVMs on macro- and microvascular hemodynamics.

10:36 0515.   Applications of Dynamic Contrast Enhanced MRI in Neurovascular Disease
Parmede Vakil1, Michael C Hurley2, Shyam Prabhakaran2, Bernard Bendok2, H. Hunt. Batjer3, Timothy J Carroll2, and Sameer A Ansari2
1Northwestern University, Chicago, IL, United States, 2Northwestern University, IL, United States, 3UT Southwestern, Texas, United States

Applications of dynamic contrast enhanced MRI in neurovascular diseases such as intracranial aneurysms, intracranial atherosclerotic disease, and vasculitis have not been previously explored. We demonstrate the utility of DCE-MRI in a study of patients with various neurovacular pathologies.

10:48 0516.   
Comprehensive Hemodynamic Evaluation of Intracranial Atherosclerotic Disease with 4D Flow MR Imaging
Can Wu1, Shyam Prabhakaran2, Timothy Carroll1,3, Parmede Vakil3, Neil Chatterjee1,3, Amir Honarmand3,4, Sameer Ansari3,4, James Carr3, and Michael Markl1,3
1Biomedical Engineering, Northwestern University, Chicago, IL, United States, 2Neurology, Northwestern University, Chicago, IL, United States,3Radiology, Northwestern University, Chicago, IL, United States, 4Neurological Surgery, Northwestern University, Chicago, IL, United States

The purpose of this study was to evaluate the feasibility of 4D flow MR imaging for the comprehensive evaluation of intracranial hemodynamics in 20 patients with intracranial atherosclerotic disease (ICAD) including quantitative analysis of peak velocity and mean blood flow in the large intracranial vessels. The results demonstrated significant impact of regional stenotic lesions on the hemodynamics in systemic vascular territories. Combined evaluation of the qualitative visualization of the blood flow patterns and distribution of blood flow velocities and quantitative hemodynamic markers may provide additional insight into the pathophysiology and risk stratification for ICAD patients.

11:00 0517.   Comparison of digital subtraction angiography with 3D high-resolution MR vessel wall imaging for the evaluation of basilar artery atherosclerotic stenosis and plaque distribution
Aofei Liu1, Xihai Zhao2, Huijun Chen2, Zhensen Chen2, William Kerwin3, Chun Yuan2,3, Bin Du1, and Wei-Jian Jiang1
1New Era Stroke Care and Research Institute, The Second Artillery General Hospital PLA, Beijing, China, 2Center for Biomedical Imaging Research & Department of Biomedical Engineering, Tsinghua University, Beijing, China, 3Department of Radiology, University of Washington, Seattle, WA, United States

We sought to compare DSA and MR vessel wall imaging in evaluating the degree of stenosis and plaque distribution in BA. Of 31 subjects, the stenotic degree measured by DSA and MRI was 32.9% and 42.9% respectively. Excellent agreement was found between DSA and MRI in stenosis measurement (r=0.898, P<0.001). DSA underestimated the degree of luminal stenosis, which may be due to its limitation in viewing eccentrically stenotic lesion. The incidence of plaque affecting each quadrant on MRI is greater than that of DSA, suggesting MR vessel wall imaging may be a better imaging modality to evaluate lesion distribution in BA.

11:12 0518.   Intracranial vessel wall imaging with simultaneous blood and CSF suppression
Jinnan Wang1, Michael Helle2, Zechen Zhou3, Peter Börnert2, and Chun Yuan4
1Philips Research North America, Seattle, WA, United States, 2Philips Research Europe, Hamburg, Hamburg, Germany, 3Tsinghua University, Beijing, Beijing, China, 4University of Washington, Seattle, WA, United States

Intracranial artery atherosclerosis is a key contributor of stroke. MR evaluation of the vessel wall has been technically challenging because of the difficulty of suppressing blood and CSF at the same time. In this study, a simultaneous blood and CSF suppression was developed and tested in vivo. This technique essentially provides an effective way to achieve multi-contrast intracranial atherosclerosis imaging, creating a unique solution to study the clinical impact of intracranial artery disease.

11:24 0519.   The influence of computational strategy on prediction of MRI-based mechanical stress in carotid atherosclerotic plaques: comparison of 2D structure-only, 3D structure-only, one-way and fully coupled FSI analyses
Yuan Huang1, Zhongzhao Teng1,2, Umar Sadat3, and Jonathan H Gillard1
1University Department of Radiology, University of Cambridge, Cambridge, Cambridge, United Kingdom, 2Department of Engineering, University of Cambridge, Cambridge, United Kingdom, 3Department of Surgery, Cambridge University Hospitals NHS Foundation Trust, Cambridge, Cambridge, United Kingdom

Plaque composition detected by imaging alone cannot accurately predict future cerebrovascular risk, and additional analyses or biomarkers are required. Under physiological conditions, carotid plaques are subjected to mechanical loading from pulsatile blood pressure. FC rupture may occur when this loading exceeds its material strength. Different computational strategies, including 2D structure-only, 3D structure-only, 3D one-way and fully coupled fluid-structure interaction (FSI), have been employed to examine plaque stress. This study indicated that 2D simulations yielded a poor performance in predicting stress and 3D structural-only models showed good qualitative and quantitative agreement with the 3D fully coupled FSI.

11:36 0520.   
Cerebral microinfarcts determined at 7T MRI are associated with a thin fibrous cap in ipsilateral carotid atherosclerotic plaque
Alexandra A.J. de Rotte1, Wouter Koning2, Anne G. den Hartog3, Sandra M. Bovens4, Aryan Vink5, Shahrzad Sepehrkhouy5, Jaco J.M. Zwanenburg6, Dennis W.J. Klomp6, Gerard Pasterkamp7, Frans L. Moll3, Peter L. Luijten6, Gert Jan de Borst3, and Jeroen Hendrikse6
1Radiology, University Medical Center Utrecht, Utrecht, Utrecht, Netherlands, 2University Medical Center Utrecht, Utrecht, Netherlands, 3Vascular Surgery, University Medical Center Utrecht, Utrecht, Netherlands, 4Bioengineering, Imperial College London, London, United Kingdom, 5Pathology, University Medical Center Utrecht, Utrecht, Netherlands, 6Radiology, University Medical Center Utrecht, Utrecht, Netherlands, 7Experimental Cardiology, University Medical Center Utrecht, Utrecht, Netherlands

First, the use ultra-high field 7T MR imaging to visualize the total burden of cerebral infarcts (both macro- and microinfarcts) was evaluated. Second, the presence of micro- and macroinfarcts was correlated with histopathology of carotid artery plaque. This study shows that a histopathological thinner fibrous cap is associated with more infarcts (both micro and macroinfarcts) in the hemisphere ipsilateral to a >70% symptomatic carotid artery stenosis. Other histopathological plaque characteristics were not related to infarcts (micro and macro). Microinfarcts are common in this patient group with symptomatic carotid artery stenosis but are most often find in combination with macroinfarcts.

11:48 0521.   Pronounced Visibility of Cerebral Venous Vasculature in Small Vessel Disease; A Susceptibility-weighted Imaging Study  - permission withheld
Farhang F Jalilian1,2, David E Crane1, FuQiang Gao1, Sandra E Black1,3, and Bradley J MacIntosh1,2
1Heart and Stroke Foundation Canadian Partnership for Stroke Recovery, Sunnybrook Research Institute, Toronto, ON, Canada, 2Medical Biophysics, University of Toronto, Toronto, ON, Canada, 3Division of Neurology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada

Cerebral Small Vessel Disease (SVD) is the most prevalent disease that affects the brain. We investigate the use of susceptibility-weighted imaging (SWI) in visualizing medullary veins and assessing the SVD. The study involves automatic segmentation of: 1) venous vasculature and 2) white matter lesions. Our results show there is a higher vein fraction in white matter lesions compared to normal white matter, and a positive correlation between periventricular vein fraction and SVD lesion burden. Our findings showcase the utility of SWI and highlight the importance of investigating the venous vasculature for its involvement in the etiology of the SVD.