1. From the Departments of Radiology (A.K., L.J.M., D.M., C.Z., M.W., D.B.L.), Neurology and Neurological Sciences (S.C., N.V.), and Emergency Medicine (G.O.), Stanford University School of Medicine, Stanford Hospital and Clinics, Stanford, Calif; and Neuroscience Service Line, Department of Medicine, Christiana Care Health System, Newark, Del (W.A.T.).