1. Departments of Radiology (K.S., J.Y., P.F., T.T., I.A.M., T.Q., T.D.E., D.Y.C., M.A.Y., S.S., C.A.), Massachusetts General Hospital, Harvard Medical School, Boston.
2. Department of Neurosurgery, Yamaguchi University School of Medicine, Japan (K.S.).
3. Neurology (D.Y.C., C.A.), Massachusetts General Hospital, Harvard Medical School, Boston.