Figure 3a.  (a) Axial three-dimensional time-of-flight MR angiogram shows a normal basilar artery (arrowhead), carotid artery, and right vertebral artery (curved arrow) intracranially. The left vertebral artery has reduced flow (straight arrow). (b) Coronal three-dimensional time-of-flight MR angiogram reveals irregular contour and reduced flow in the left vertebral artery between the transverse foramen of C2 and C1 (curved arrows). The large vessels lateral to the vertebral artery (straight arrow) are jugular veins that could not be totally suppressed on the image due to the angle of acquisition.