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

Advanced Stroke Imaging
Tuesday 23 April 2013
Room 155 EF  10:00 - 12:00 Moderators: Jeroen Hendrikse, Lawrence N. Tanenbaum

10:00 0204.   The Robustness of DSC-PWI for Acute Stroke Imaging; Timing Is Everything: The Vanishing Perfusion Abnormality.
Irene Klaerke Mikkelsen1, Lars Riisgaard Ribe1, Susanne Lise Bekke1, Kim Mouridsen1, and Leif Østergaard1
1Center for Functionally Integrative Neuroscience, Aarhus University Hospital, Aarhus, Denmark

In patients with acute ischemic stroke, millions of neurons die by the minute. For those who are eligible for thrombolytic therapy, the duration of diagnostic DSC-scans are therefore reduced to a minimum. This study shows that this practice may lead to severe underestimation of the perfusion abnormality, and therefore the therapeutic target. The degree of underestimation is investigated for three different deconvolution techniques.

10:12 0205.   Multi-Delay Multi-Parametric Arterial Spin-Labeled Perfusion MRI in Acute Ischemic Stroke – Comparison with Dynamic Susceptibility Contrast Enhanced Perfusion Imaging
Danny J.J. Wang1,2, David S. Liebeskind1, Joe X. Qiao2, Matthias Günther3, Whitney B. Pope2, Jeffrey L. Saver1, Noriko Salamon2, and Jeffry R. Alger1,2
1Neurology, UCLA, Los Angeles, CA, United States, 2Radiology, UCLA, Los Angeles, CA, United States, 3Institute for Medical Image Computing, University of Bremen, Bremen, Germany

A novel multi-delay multi-parametric pseudo-continuous ASL (pCASL) protocol was presented. Its accuracy was evaluated by comparison with dynamic susceptibility contrast (DSC) enhanced perfusion MRI in 29 patients with acute and subacute ischemic stroke. Consistent results between multiple hemodynamic parameters derived using ASL and DSC were demonstrated.

10:24 0206.   Derivation of Flow Information from a Hypocarbia Challenge Study Using Time Delay Correlation Processing
Blaise Frederick1,2, Yunjie Tong1,2, Megan Strother3, Lisa Nickerson1,2, Kim Lindsey1,2, and Manus Donahue3
1Brain Imaging Center, McLean Hospital, Belmont, MA, United States, 2Department of Psychiatry, Harvard Medical School, Boston, MA, United States,3Department of Radiology, Vanderbilt University, Nashville, TN, United States

We present a novel analysis technique which allows the extraction of detailed cerebrovascular flow information from fMRI data acquired during a hypercarbia challenge. Flow data is derived in 20 subjects, and comparison of flow before and after surgical intervention is performed.

10:36 0207.   Noninvasive Multi-Echo Vessel-Encoded Arterial Spin Labeling Reactivity for More Comprehensive Quantification of Hemodynamic Compensation: Development and Clinical Implementation in 50 Patients with Cerebrovascular Disease
Manus J. Donahue1, Paul Clemmons1, Ricardo Andal1, Robert Singer1, Diane Brown1, Morgan Anderson1, Dan Claassen1, John Connors1, Lisa Hermann1, Lori Jordan1, Howard Kirshner1, J. Mocco1, Ryan Moore1, Anne O'Duffy1, Derek Riebau1, Allen Sills1, and Megan Strother1
1Vanderbilt University, Nashville, TN, United States

The purpose of this work is to develop and clinically implement a noninvasive MRI protocol for quantifying the relationship between key hemodynamic compensation mechanisms including cerebrovascular reactivity (CVR), baseline cerebral blood flow (CBF), CBF reactivity, and CBF territory dynamics in patients with cerebrovascular disease. This approach was implemented in 50 patients and results illuminated impairment not clear from structural imaging.

10:48 0208.   Cerebral Perfusion and Vascular Reactivity in Insulin Resistance and Obesity
Henry Rusinek1, Jenny Ha2, Po Lai Yau2, Aziz Tirsi2, Wai Hon Tsui2, and Antonio Convit2
1Radiology, NYU School of Medicine, New York, New York, United States, 2Psychiatry, NYU School of Medicine, New York, New York, United States

The obesity epidemic is responsible for the increasing prevalence of Type 2 diabetes (DB). Using a high-resolution ASL we present evidence that brain perfusion and vascular reactivity are affected in the early stage of DB. Insulin resistant (IR) subjects had significantly lower (p=0.008) resting gray matter flow (60.0±4.5) compared to healthy controls (63.6±6.4), with a trend for hypoperfusion in DB. There was a significant detrimental effect of obesity on vascular reactivity. Our findings suggest that cerebral blood flow and vascular reactivity changes resulting from obesity and insulin resistance are reversible.

11:00 0209.   
Evaluation of a Multiparamteric QBOLD Approach in Acute Stroke Patients
Julien Bouvier1,2, Olivier Detante1, Irène Troprès3, Sylvie Grand1,4, David Chechin2, Jean-François Le Bas3,4, Alexandre Krainik1,4, and Emmanuel Luc Barbier1
1INSERM U836, Grenoble Institute of Neurosciences, Grenoble, France, 2Philips Healthcare, Suresnes, France, 3Plate-forme IRMaGe, UJF – INSERM US17 – CNRS UMS 3552, Grenoble, France, 4CHU de Grenoble, Clinique Universitaire de Neuroradiologie et d’IRM, Grenoble, France

In stroke, Perfusion Weigthed Imaging (PWI) allows the identification of hypoperfused tissues. MRI characterization of the ischemic penumbra, defined by the diffusion-perfusion mismatch, can delineate penumbral and irreversibly infarcted fields with a similar degree of reliability to the gold standard, positron-emission tomography (PET). The presence of a diffusion-perfusion mismatch could justify thrombolysis therapy beyond 3h. The assessment of the penumbra using MRI remains controversial, however. The aim of this study is to evaluate how tissular oxygen saturation (StO2), assessed with a multiparametric qBOLD approach, fits between diffusion and perfusion acute stroke patients.

11:12 0210.   
Brain Connectivity and CBF Canges Fllowing Motor Training by MI-BCI Combined with TDCS in Stroke Patients
Xin Hong1, Yan Zhi Ong2, Irvin Teh3, Fatima Ali Nasrallah1, Zhong Kang Lu4, Wei Peng Teo5, Cuntai Guan4, Kai Keng Ang4, Kok Soon Phua4, Ling Zhao5, Effie Chew5, and Kai-Hsiang Chuang1
1Singapore Bioimaging Consortium, Singapore, Singapore, 2Department of Biological Sciences, National University of Singapore, Singapore, Singapore, 3A*STAR-NUS Clinical Imaging Research Centre, Singapore, Singapore, 4Institute for Infocomm Research, Singapore, Singapore, 5The Division of Neurology and Rehabilitation Medicine, National University Hospital System, Singapore, Singapore

Perfusion and diffusion MRI were used to understand the plasticity in gray and white matters after motor training in stroke patients with impaired upper extremity. Robot-assisted motor imagery and brain-computer interface (MI-BCI) combined with or without transcranial direct current stimulation (tDCS) were conducted. Brain CBF change and FA changes along motor related fiber tracts are found after 2 weeks of training and correlate with clinical improvement. tDCS did not show significant effects on motor recovery. These findings will be helpful in understanding the role of neuroplasticity in motor recovery, and in the development of effective therapeutic approach for stroke rehabilitation.

11:24 0211.   Dual-Echo Diffusion-Weighted EPI for Better Sensitivity to Acute Stroke
Samantha J. Holdsworth1, Stefan Skare2, Kristen Yeom1, Michael U. Antonucci1, Jalal B. Andre3, Jarrett Rosenberg1, Matus Straka1, Nancy J. Fischbein1, Greg Zaharchuk1, and Roland Bammer1
1Department of Radiology, Stanford University, Palo Alto, CA, United States, 2Karolinska Institute, Clinical Neuroscience, Stockholm, Sweden, 3Department of Radiology, University of Washington, Seattle, WA, United States

Here we investigate an alternative approach to diffusion-weighting imaging (DWI) with the use of a parallel-imaging enhanced dual-echo sequence. It was found that dual-echo DWI is a powerful method for evaluating diffusion-restricting lesions. The long echo time of Echo 2 gives rise to DW images that exhibit superior sensitivity to diffusion lesions than DW images acquired at a shorter echo time; Echo 1 provides high SNR ADC maps for specificity to acute stroke; and the information from both echoes is a potential source of complementary information for the assessment of blood and mineralization products.

11:36 0212.   
Subcortical Volumetric Differences in Children with Sickle Cell Disease and Silent Infarction
Jamie M. Kawadler1, Jonathan D. Clayden2, Fenella J. Kirkham3, and Christopher A. Clark2
1Imaging & Biophysics Unit, UCL Institute of Child Health, London, United Kingdom, 2Imaging & Biophysics Unit, University College London, London, United Kingdom,3Neurosciences Unit, UCL Institute of Child Health, London, United Kingdom

This work investigates for the first time specific subcortical structure volumes in children and adolescents with sickle cell disease, which has been shown to affect cortical grey matter and deep white matter.

11:48 0213.   Amide Proton Transfer (APT) Imaging of Acute Cerebral Infarction: A Preliminary Study on Clinical Patients
Takashi Yoshiura1, Akio Hiwatashi1, Osamu Togao2, Jochen Keupp3, Koji Yamashita1, Kazufumi Kikuchi1, Yuriko Suzuki4, Makoto Obara4, and Hiroshi Honda1
1Department of Clinical Radiology, Kyushu University, Fukuoka, NA, Japan, 2Department of Molecular Imaging and Diagnosis, Kyushu University, Fukuoka, NA, Japan, 3Technical Systems, Philips Research Laboratories, Hamburg, NA, Germany, 4Philips Electronics Japan, Tokyo, NA, Japan

Animal experiments have shown that APT imaging can detect lowered pH in acute cerebral infarction, but evidence for human stroke patients is extremely limited in amount. Our purpose was to test the feasibility of APT imaging in assessing clinical acute infarction. APT imaging data from 8 patients with acute infarctions showed significantly reduced APT signal in infarcted tissue compared to normal tissue, demonstrating the clinical feasibility of APT imaging. Moreover, we found that APT contrast between normal ad infarcted tissues was critically dependent on the saturation time, suggesting the importance of imaging parameter optimization.