1. From the Department of Diagnostic and Interventional Neuroradiology, Clinic of Radiology and Nuclear Medicine (M.S., A.B., M.N.P., K.A.B.), and Department of Radiology and Nuclear Medicine (T.W., A.S.), University Hospital of Basel, Petersgraben 4, 4031 Basel, Switzerland; and Department of Neurologic Sciences, University of Vermont Medical Center, Burlington, Vt (M.S.).