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(Stroke. 2008;39:2021.)
© 2008 American Heart Association, Inc.
Original Contributions |
From the Department of Medical Imaging (D.M.M., J.P., A.P.C., J.A.S., D.J.M.), Toronto Western Hospital, Toronto, Ontario, Canada; the Departments of Medical Imaging (D.M.M., D.J.M.) and Physiology (J.S.H., J.A.F.), University of Toronto, Toronto, Ontario, Canada; GE Healthcare (J.A.S.), Milwaukee, Wisc, USA; and the Department of Anesthesia (J.S.H.), Toronto General Hospital, Toronto, Ontario, Canada.
Correspondence to David J. Mikulis, MD, Department of Medical Imaging, Toronto Western Hospital, Department of Medical Imaging, University of Toronto, Room 3MC-431, Toronto Western Hospital, 399 Bathurst Street, Toronto, Ontario M5T 2S8, Canada. E-mail mikulis{at}uhnres.utoronto.ca
Background and Purpose— Blood oxygen level-dependent MRI (BOLD MRI) of hypercapnia-induced changes in cerebral blood flow is an emerging technique for mapping cerebrovascular reactivity (CVR). BOLD MRI signal reflects cerebral blood flow, but also depends on cerebral blood volume, cerebral metabolic rate, arterial oxygenation, and hematocrit. The purpose of this study was to determine whether, in patients with stenoocclusive disease, the BOLD MRI signal response to hypercapnia is directly related to changes in cerebral blood flow.
Methods— Thirty-eight patients with steno-occlusive disease underwent mapping of CVR by both BOLD MRI and arterial spin labeling MRI. The latter technique was used as a reference standard for measurement of cerebral blood flow changes.
Results— Hemispheric CVR measured by BOLD MRI was significantly correlated with that measured by arterial spin labeling MRI for both gray matter (R=0.83, P<0.0001) and white matter (R=0.80, P<0.0001). Diagnostic accuracy (area under receiver operating characteristic curve) for BOLD MRI discrimination between normal and abnormal hemispheric CVR was 0.90 (95% CI=0.81 to 0.98; P<0.001) for gray matter and 0.82 (95% CI=0.70 to 0.94; P<0.001) for white matter. Regions of paradoxical CVR on BOLD MRI had a moderate predictive value (14 of 19 hemispheres) for spatially corresponding paradoxical CVR on arterial spin labeling MRI. Complete absence of paradoxical CVR on BOLD MRI had a high predictive value (31 of 31 hemispheres) for corresponding nonparadoxical CVR on arterial spin labeling MRI.
Conclusions— Arterial spin labeling MRI confirms that, even in patients with stenoocclusive disease, the BOLD MRI signal response to hypercapnia predominantly reflects changes in cerebral blood flow.
Key Words: carotid stenosis cerebral blood flow cerebrovascular disease Moyamoya MRI
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