Computerized tomography in selected intracranial vascular abnormalities.

Computerized axial tomography (CAT) is a reliable technic for examining patients with a variety of intracranial abnormalities. In acute lesions where there is extravasated blood, the CAT scan shows areas of increased density on the precontrast study which measures 70 to 90 Hounsfield units. In lesions with increased flow or blood volume, the postcontrast study reveals areas of increased density due to greater pooling of contrast medium. In areas of nonhemorrhagic ischemia the CAT scan shows persisting low density.