Regional Ischemic Vulnerability of the Brain to Hypoperfusion

Background and Purpose—To characterize the spatial pattern of cerebral ischemic vulnerability to hypoperfusion in stroke patients. Methods—We included 90 patients who underwent admission CT perfusion and MRI within 12 hours of ischemic stroke onset. Infarcted brain lesions (“core”) were segmented from admission diffusion-weighted imaging and, along with the CT perfusion parameter maps, coregistered onto MNI-152 brain space, which was parcellated into 125 mirror cortical and subcortical regions per hemisphere. We tested the hypothesis that the percent infarction increment per unit of relative cerebral blood flow (rCBF) reduction differs statistically between regions using regression analysis to assess the interaction between regional rCBF and region variables. Next, for each patient, a “vulnerability index” map was constructed with voxel values equaling the product of that voxel's rCBF and infarction probability (derived from the MNI-152–transformed, binary, segmented, diffusion-weighted imaging lesions). ...