Diagnostic value of perfusion MRI in classifying stroke.

: Our study was designed to determine whether supplementary information obtained with perfusion MRI can enhance accuracy. We used delayed perfusion, as represented by time to peak map on perfusion MRI, to classify strokes in 39 patients. Strokes were classified as hemodynamic if delayed perfusion extended to a whole territory of the occluded arterial trunk; as embolic if delayed perfusion was absent or restricted to infarcts; as arteriosclerotic if infarcts were small, multiple, and located mainly in the basal ganglias; or as unclassified if the pathophysiology was unclear. We compared these findings with vascular lesions on cerebral angiography, neurological signs, infarction on MRI, ischemia on xenon-enhanced CT (Xe/CT) and collateral pathway development. Delayed perfusion clearly indicated the area of arterial occlusion. Strokes were classified as hemodynamic in 13 patients, embolic in 14 patients, arteriosclerotic in 6 patients and unclassified in 6 patients. Hemodynamic infarcts were seen only in deep white-matter areas such as the centrum semiovale or corona radiata, whereas embolic infarcts were in the cortex, cortex and subjacent white matter, and lenticulo-striatum. Embolic and arteriosclerotic infarcts occurred even in hemo-dynamically compromised hemispheres. Our findings indicate that perfusion MRI, in association with a detailed analysis of T2-weighted MRI of cerebral infarcts in the axial and coronal planes, can accurately classify stroke as hemodynamic, embolic or arteriosclerotic.