Pathology and neuroimaging of coagulation necrosis in cerebral infarcts

Tissue which has undergone coagulation necrosis (CN) after cerebral infarct is firmer than normal and sharply delimited, and these abnormalities may persist for months or years. This report examines some unusual features, visible on a computed tomography (CT) scan, in two autopsy verified CN cases. In the first case, a ring-shaped enhancement was visible 3 months after the onset of cerebral infarction, which may reflect blood flow in small vessels associated with the collagen capsule. In the second case, a lesion was observed showing hypo-intensity on a T2-weighted image and hyperintensity on a T1-weighted image 4 years after onset. These changes could be attributable to calcium or cholesterin deposition or changes in the collagen capsule. Because CN associated with cerebral infarct is not as rare as previously reported, care should be taken in the interpretation of CT findings which exhibit these features.