Axial T2W shows the enlarged left vertebral artery, measuring A 2.5 X 2.7 CMS. round mass in pre-pontine cistern. The lesion is predominantly hyperintense. There is evidence of haemorrhage within the lesion. TOF sequence shows the sac of the basilar artery aneurysm. Note the normal terminal segment and PCA branches.
Contrast-enhanced MRI shows the giant aneurysm of basilar artery mid-segment. The neck of the aneurysm is seen on coronal plane.