Identification of cerebral ischemic lesions in rat using eigenimage filtered magnetic resonance imaging

An accurate noninvasive time-independent identification of an ischemic cere bral lesion is an important objective of magnetic resonance imaging (MRI). This study describes a novel application of a multiparameter MRI analysis a lgorithm, the Eigenimage (EI) filter, to experimental stroke. The EI is a l inear filter that maximizes the projection of a desired tissue (ischemic ti ssue) while it minimizes the projection of undesired tissues (nonischemic t issue) onto a composite image called an eigenimage. Rats (n = 26) were subj ected to permanent middle cerebral artery occlusion. T2- and T1-weighted co ronal MRT were acquired on separate groups of animals. The animals were imm ediately sacrificed after each imaging session for histopathological analys is of tissue at 4-8 h, 16-24 h, and 48-168 h after stroke onset. Lesion are as from MRI were defined using EI. The Ed defined lesion areas were coregis tered and warped to the corresponding histopathological sections. The ische mic lesion as defined by EI exhibited ischemic cell damage ranging from sca ttered acute cell damage to pan necrosis. Ischemic cellular damage was not detected in homologous contralateral hemisphere regions. EI lesion areas ov erlaid on histopathological sections were significantly correlated (r = 0.9 2, p < 0.05) acutely, (r = 0.98, p < 0.05) subacutely, and (r = 0.99, p < 0 .05) chronically. These data indicate that EI methodology can accurately se gment ischemic damage after MCA occlusion from 4-168 h after stroke. (C) 19 99 Elsevier Science B.V. All rights reserved.