Contrast enhancement of cerebral infarcts in computed tomography.

Approximately 60% of cerebral infarcts between 1 and 4 weeks old may be enhanced by contrast material. A recent infarct can be missed if contrast material is not used; however, recent infarcts can also be partially obscured by the contrast medium, so that a precontrast scan is necessary. Infarcts, arteriovenous malformations, and gliomas may appear similar on the CT scan. Recent infarcts can have a significant mass effect (seen in 22% of cases), and their anatomical location and morphology may or may not be helpful in the differential diagnosis. Ipsilateral ventricular dilatation, homogeneous low-density areas, and sharp margins are usually found in older infarcts.