1. From the Departments of Radiology (M.J.D., L.M.D., C.C.F., A.D., J.C., M.K.S.), Neurology (M.J.D., L.C.J., P.C., A.O., D.R., L.H., H.K.), Psychiatry (M.J.D.), Physics (M.J.D.), and Neurosurgery (J.M., J.C., M.K.S.) and Center for Quantitative Sciences (Y.S.), Vanderbilt University, Nashville, TN; and Department of Neurosurgery, Geisel School of Medicine, Dartmouth College, Lebanon, NH (R.S.);