ISMRM 23rd Annual Meeting & Exhibition • 30 May - 05 June 2015 • Toronto, Ontario, Canada

Scientific Session • Neurovascular & Stroke 1

Monday 1 June 2015

John Bassett Theatre 102

14:15 - 16:15



14:15 0161.   Changes in White-matter Integrity and Evoked fMRI Responses in Chronic Hypertension
Yunxia Li1,2, Qian Wang1, Qiang Shen1, Shiliang Huang1, Lora Talley Watts1, and Timothy Q Duong1
1Research Imaging Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States, 2Department of Neurology, Tongji Hospital, Tongji University, Shanghai, China

Chronic hypertension increases susceptibility to neurological disorders. The goal of this study was to evaluate cerebral blood flow (CBF) and cerebrovascular reactivity (CR) in response to hypercapnia in an established rat model of hypertension (SHR) at different stages of the disease progression. Comparisons were made with age-matched normotensive Wistar Kyoto (WKY) rats. CBF and CR were altered in early stage of chronic hypertension and worsen with disease progression, ultimately resulting in hypoperfusion and compromised cerebrovascular reserve. MRI has the potential to be used to identify brain regions susceptible to hemodynamic compromise, improve understanding of disease pathogenesis, guider treatments in hypertension.

14:27 0162.   
Multi-modality 4D Stroke Template for the Characterization of Arterial Ischemic Stroke Evolution Over Time
Samantha J Ma1, David S Liebeskind1, Songlin Yu1, Holly Wilhalme2, David Elashoff2, Xin J Qiao3, Nerses Sanossian1, Sidney Starkman1,4, Latisha K Ali1, Fabien Scalzo1, Bryan Yoo3, Jeffrey L Saver1, Noriko Salamon3, and Danny JJ Wang1
1Neurology, UCLA, Los Angeles, CA, United States, 2Medicine Statistics Core, UCLA, Los Angeles, CA, United States, 3Radiology, UCLA, Los Angeles, CA, United States, 4Emergency Medicine, UCLA, Los Angeles, CA, United States

Serial neuroimaging that includes both pre- and post-therapy time points provides insight on the dynamics of reperfusion and may be useful in the guidance of further interventions. Here we demonstrate that a multi-modal four-dimensional ischemic stroke template of middle cerebral artery (MCA) stroke can be used to characterize the effects of thrombolytic intervention over time as ischemic brain tissue makes the transition from injury into repair. As the injured brain tissue evolves with time, there is clear evidence that treatment induces a significant hyperemic response in hypoperfused regions. By contrast, tissue that is left untreated exhibits incomplete reperfusion.

14:39 0163.   Variations in cerebral haemodynamics and capillary transit time heterogeneity in patients before and after carotid endarterectomy
Amit Mehndiratta1,2, Chang Sub Park2, David E Crane3, Ediri Sideso4, James Kennedy5, Bradley J MacIntosh3, Stephen J Payne2, and Michael A Chappell2
1CBME, Indian Institute of Technology Delhi, New Delhi, Delhi, India, 2IBME, University of Oxford, Oxford, Oxfordshire, United Kingdom, 3Medical Biophysics, Sunnybrook Research Institute, Toronto, ON, Canada, 4Nuffield Department of Surgery, University of Oxford, Oxford, Oxfordshire, United Kingdom, 5Acute Vascular Imaging Centre, Radcliffe Department of Medicine, University of Oxford, Oxford, Oxfordshire, United Kingdom

Reliable estimation of capillary transit time distribution (TTD) and transit time heterogeneity (CTH) has been questioned in literature. With CPI it is possible to evaluate the variations in TTD in vivo. The results from our analysis in 17 patients with carotid atherosclerotic disease imaged both before and after CEA showed that under the currently used standard DSC-MRI imaging protocol more than 80% of the pathophysiological variability in the data can be explained with only one component.

14:51 0164.   
A multi-parametric investigation of vascular alterations in elderly with hypertension
Min Sheng1, Kevin S. King2, Adam Sheffield3, Harshan Ravi1, Shin-Lei Peng1, Peiying Liu1, Zohre German4, and Hanzhang Lu1
1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States, 2Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States, 3Medical program, University of Texas Southwestern Medical Center, Dallas, Texas, United States, 4Department of Neurology, University of Texas Southwestern Medical Center, Dallas, Texas, United States

Hypertension is a major risk factor for stroke, dementia, and cognitive decline. In order to investigate more sensitive biomarker of vascular dysfunction in the brain, we conducted a multiparametric investigation of hemodynamic changes in hypertension, including cerebral blood flow (CBF), venous cerebral blood volume (vCBV), venous oxygenation (Yv), and cerebrovascular reactivity (CVR) to CO2. In this study, we found that CBF and Yv increased with blood pressure while CVR decreased with blood pressure in elderly subjects. vCBV did not show any difference in hypertension. These vascular markers may precede structural changes of the brain and clinical symptoms.

15:03 0165.   A Non-Invasive Method for Measuring Perfusion in Moyamoya disease with Functional Magnetic Resonance Imaging
Tianyi Qian1, Zhiwei Zuo2, Yituo Wang2, Yuanyuan Kang3, Penggang Qiao2, and Gongjie Li2
1MR Collaborations NE Asia, Siemens Healthcare, Beijing, Beijing, China, 2Radiology, Affiliated hospital of Academy of Military Medical Sciences, Beijing, China, 3Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, China

Moyamoya disease (MMD) is defined in angiography as a chronic progressive steno-occlusion of internal carotid arteries with characteristically abnormal vascular networks at the base of the brain. In this study, by analyzing the rs-fMRI data with the iteration algorithm described in this paper, the perfusion deficit areas that had long TTP value could be detected non-invasively. The results of our technique match well with TTP maps from DSC-MR and could be a good alternative for monitoring long-term changes of cerebral blood flow pattern in MMD frequently.

15:15 0166.   
Postischemic Hyperperfusion on Arterial Spin Labeled Perfusion MRI is Linked to Hemorrhagic Transformation in Stroke
Songlin Yu1, David S Liebeskind1, Sumit Dua2, Holly Wilhalme3, David Elashoff3, Xin J Qiao2, Jeffry R Alger1,2, Nerses Sanossian1, Sidney Starkman1,4, Latisha K Ali1, Fabien Scalzo1, Xin Lou1,5, Jeffrey L Saver1, Noriko Salamon2, and Danny J.J. Wang1,2
1Neurology, UCLA, Los Angeles, CA, United States, 2Radiology, UCLA, Los Angeles, CA, United States, 3Medicine Statistics Core, UCLA, Los Angeles, CA, United States, 4Emergency Medicine, UCLA, Los Angeles, CA, United States, 5Radiology, Chinese People’s Liberation Army (PLA) General Hospital, Beijing, China

The study investigated the relationship between postischemic hyperperfusion on arterial spin labeled (ASL) and hemorrhagic transformation (HT). 361 ASL scans were collected from 221 acute ischemic stroke patients (AIS). Hyperperfusion was more frequently detected post-treatment. Having hyperperfusion at any time point related significantly to HT (OR=3.5, 95%CI 2.0-6.3, P<0.001). There was a trend that patients with first hyperperfusion after 12 hours from stroke onset were more likely to experience severe HT than those with first hyperperfusion within 12 hours (Fisher's exact p-value = 0.06). ASL hyperperfusion may provide an imaging marker of HT and guide the management of AIS patients.

15:27 0167.   
Hemodynamics of the cerebral border zone regions in healthy, young volunteers
Sophie Schmid1, Wouter Teeuwisse1, Hanzhang Lu2, and Matthias van Osch1
1Radiology, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands, 2UT Southwestern Medical Center, Dallas, Texas, United States

In this study we employed Time encoded (aka. Hadamard encoded) pseudo Continuous Arterial Spin Labeling combined with T2-Relaxation-Under-Spin-Tagging to evaluate the hemodynamics of the posterior and middle cerebral artery border zone regions in the brains of healthy, young volunteers. A significantly lower CBF was found in the border region compared with the central region in both the posterior and MCA flow territory. The arterial transit time in the border zone is significantly longer compared to the central region. However, the exchange of the label from the arterial to the tissue compartment appears to be at a similar rate.

15:39 0168.   
Velocity and wall shear stress in the Circle of Willis in Sickle Cell Disease using 4D flow MRI
Lena Vaclavu1, Henk-Jan Mutsaerts1, Wouter Potters1, Veronica van der Land1, Karin Fijnvandraat1, Michael Markl2, Charles Majoie1, Aart Nederveen1, and Pim van Ooij1
1Academic Medical Center AMC, Amsterdam, Noord-Holland, Netherlands, 2Radiology & Biomedical Engineering, Northwestern University, Chicago, IL, United States

Wall shear stress (WSS) is the tangential force exerted by the flowing blood on the endothelial wall and is dependent on the dynamic viscosity of blood. ). Endothelial dysfunction in SCD could be related to low WSS but this hasn’t been studied in the circle of willis (CoW), whereas low WSS in carotid has been shown to be atheroprotective.SCD is associated with increased risk for stroke and vasculopathy and therefore serves as an interesting patient population to investigate in relation to WSS. In this pilot study, we explore the feasibility of 4D flow MRI and WSS estimation in the CoW, and the Middle Cerebral Artery.

15:51 0169.   Automatic Segmentation of the Venous Vessel Network Based on Quantitative Susceptibility Maps and its Application to Investigate Blood Oxygenation
Barthélemy Serres1, Andreas Deistung1, Andreas Schäfer2, Marek Kocinski3, Andrzej Materka3, and Jürgen Reichenbach1
1Medical Physics Group, Institute for Diagnosis and Interventional Radiology, University Hospital Jena - Friedrich Schiller University Jena, Jena, Germany, 2Max Plank Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, 3University of Lodz, Lodz, Poland

A common method to assess the venous blood vessel network in high-spatial detail is susceptibility weighted imaging(SWI). However, contrast on susceptibility weighted images may be non-local and there is a complex relationship between the orientation of venous vessel axis and the main magnetic field. To overcome this issue quantitative susceptibility mapping (QSM), a novel technique that enables conversion of gradient-echo phase images into maps of the magnetic susceptibility in vivo, can be applied. Due to its quantitative nature, QSM also offers the possibility to estimate oxygen saturation within blood vessels. In this contribution, we present an approach for automatic segmentation of venous vessels based on quantitative susceptibility maps to produce highly accurate 3D reconstructions of the cerebral venous network. This approach is also used to investigate blood oxygenation within the venous network.

16:03 0170.   
Longitudinal characterization of brain microstructure and visuomotor behavior following acute ocular hypertension using diffusion tensor imaging, magnetization transfer imaging and optokinetics
Yolandi van der Merwe1,2, Leon C. Ho1,3, Xiaoling Yang1,4, Michael B. Steketee4, Seong-Gi Kim1,5, Gadi Wollstein4, Joel S. Schuman2,4, and Kevin C. Chan1,4
1Neuroimaging Laboratory, University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 2Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 3Department of Electrical and Electronic Engineering, University of Hong Kong, Pokfulam, Hong Kong, China, 4Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 5Center for Neuroscience Imaging Research, Institute for Basic Science, Sungkyunkwan University, Suwon, Korea

An increase in intraocular pressure (IOP) is often associated with vision-related diseases like glaucoma and retinal ischemia, and cardiovascular diseases such as stroke. There exists a need to understand what happens in the visual pathway regarding function, structural integrity, and metabolic activity as these diseases progress. Here we used a model of ocular hypertension (OHT) induction to mimic the effects on the visual system observed in IOP increased neurodegenerative diseases. Diffusion tensor imaging, magnetization transfer imaging, and optokinetics were employed to longitudinally analyze the microstructural integrity and visuomotor behavior following OHT to help understand the disease mechanisms associated with elevated IOP.