Abstract
Intracranial aneurysms are associated with a number of pathologic conditions, including atherosclerosis, trauma, and septic emboli, but most are berry type aneurysms arising from the Circle of Willis. Cerebral angiography is the mainstay in the evaluation of these lesions and continues to be the examination of choice in the patient with subarachnoid hemorrhage; however, MR imaging and MR angiography are playing an increasingly important role, especially in screening patients at high risk for aneurysms and in the evaluation of patients with focal neurologic deficits such as cranial nerve palsies.