1. From the Departments of Neuroradiology (G.B., A.A.K.), Diagnostic and Interventional Neuroradiology (L.M., M.B., U.H., H.C.K., L.W., J.F.), Neurology (E.S.) and Institute for Medical Biometry and Epidemiology (G.S.), University Medical Center Hamburg-Eppendorf; and Department of Neuroradiology (A.K.), University Marburg, Germany.