Fig 1. A 46-year-old man with neck pain following trauma referred for MR angiography to exclude a dissection. 2D TOF demonstrates a widely patent left vertebral artery (A). MIP subvolume of the posterior circulation (B) shows an irregular possibly stenotic midleft vertebral artery that was initially felt to represent a dissection. Review of axial reformatted source images shows multiple small ring-shaped areas of signal intensity corresponding to small cervical vessels (arrow, C). The interference pattern created by these target patterns distorts the left vertebral artery resulting in ill-defined borders when compared with the right vertebral artery.