1. From the UCLA Stroke Center (L.C.S., J.L.S., J.R.A., S.S., M.C.L., F.V., G.D., R.J., J.P.V., P.M.V., C.S.K.), Department of Neurology (J.L.S., S.S., M.C.L., P.M.V., C.S.K.), Department of Radiological Sciences (J.R.A., F.V., G.D., R.J., J.P.V.), Department of Emergency Medicine (S.S.), and Department of Neurosurgery (P.M.V.), UCLA Medical Center, Los Angeles, Calif, and Department of Radiology, New York Presbyterian-Weill Cornell Medical College (Y.P.G.), New York.