FIG 4. Images obtained in a 49-year-old man with numbness of the left hand and dizziness for several days. a, Conventional angiogram of the right VA shows luminal irregularities at the intracranial verebrobasilar artery, especially the V4 segment, where alternating regions of narrowing and dilatation are noted (arrows). Luminal irregularities and occlusion were seen at the carotid systems (not shown). This is a case of atherosclerotic vascular disease. b, MIP CT angiogram shows the similar appearance of an alternatively dilated and narrowed lumen (arrows) at the V4 segment. c and d, Axial source CT angiograms at the levels of dilatation and narrowing show no evidence of mural thickening (arrow).