Cranial computed tomography and magnetic resonance imaging in autosomal dominant polycystic kidney disease.

High resolution computed tomography or magnetic resonance imaging of the head with 3-mm sections through the circle of Willis was obtained in 96 patients with autosomal dominant polycystic kidney disease. These scans are well suited for the noninvasive, presymptomatic diagnosis of intracranial aneurysms at high risk of rupture, since the risk of rupture of unruptured aneurysms is heavily dependent on their size, and aneurysms equal to or larger than 6 mm in diameter are not likely to escape detection by these techniques. No definite aneurysm was observed in any of the 96 patients. Small areas (2-4 mm) of contrast enhancement or signal void were detected in 11 patients. These areas are possibly due to vascular tortuosity, but the studies were considered to be indeterminate because a small aneurysm could not be ruled out. Cerebral angiography in two of these 11 patients was normal. Arachnoid cysts were observed more frequently in the patients with polycystic kidney disease than in a control group of patients matched by gender, age, and type and date of examination.