1. From the Departments of Neurology and Radiology (K.P., A.R., C.F., C.X., W.J.K., S.L., K.L.F., E.H.L.), Massachusetts General Hospital, Harvard Medical School, Charlestown, Mass; Department of Neurology (K.P.), Pusan National University Yangsan Hospital, Medical Research Institute, Pusan National University, Busan, Korea; Rega Institute for Medical Research (G.O.), Catholic University of Leuven, Leuven, Belgium.