Cerebral aneurysm on the middle cerebral artery.

In CT angiography, an aneurysm on the left side of the patient (note R = right) is shown in layers 90 to 107 at the middle cerebral artery. A Cerebral aneurysm is a pathological outward bulging caused by a localized, abnormal, weak spot of the vascular wall of large arteries of the brain, which can lead to subarachnoid haemorrhages.