Yunxia Li^1,2, Qian Wang¹, Qiang Shen¹, Shiliang Huang¹, Lora Talley Watts¹, and Timothy Q Duong^1
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.

Samantha J Ma¹, David S Liebeskind¹, Songlin Yu¹, Holly Wilhalme², David Elashoff², Xin J Qiao³, Nerses Sanossian¹, Sidney Starkman^1,4, Latisha K Ali¹, Fabien Scalzo¹, Bryan Yoo³, Jeffrey L Saver¹, Noriko Salamon³, and Danny JJ Wang^1
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.

Amit Mehndiratta^1,2, Chang Sub Park², David E Crane³, Ediri Sideso⁴, James Kennedy⁵, Bradley J MacIntosh³, Stephen J Payne², and Michael A Chappell^2
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.

Min Sheng¹, Kevin S. King², Adam Sheffield³, Harshan Ravi¹, Shin-Lei Peng¹, Peiying Liu¹, Zohre German⁴, and Hanzhang Lu^1
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.

Tianyi Qian¹, Zhiwei Zuo², Yituo Wang², Yuanyuan Kang³, Penggang Qiao², and Gongjie Li^2
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.

Songlin Yu¹, David S Liebeskind¹, Sumit Dua², Holly Wilhalme³, David Elashoff³, Xin J Qiao², Jeffry R Alger^1,2, Nerses Sanossian¹, Sidney Starkman^1,4, Latisha K Ali¹, Fabien Scalzo¹, Xin Lou^1,5, Jeffrey L Saver¹, Noriko Salamon², and Danny J.J. Wang^1,2
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.

Sophie Schmid¹, Wouter Teeuwisse¹, Hanzhang Lu², and Matthias van Osch^1
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.

Lena Vaclavu¹, Henk-Jan Mutsaerts¹, Wouter Potters¹, Veronica van der Land¹, Karin Fijnvandraat¹, Michael Markl², Charles Majoie¹, Aart Nederveen¹, and Pim van Ooij^1
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.

Barthélemy Serres¹, Andreas Deistung¹, Andreas Schäfer², Marek Kocinski³, Andrzej Materka³, and Jürgen Reichenbach^1
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.

Yolandi van der Merwe^1,2, Leon C. Ho^1,3, Xiaoling Yang^1,4, Michael B. Steketee⁴, Seong-Gi Kim^1,5, Gadi Wollstein⁴, Joel S. Schuman^2,4, and Kevin C. Chan^1,4
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