1. From the Seaman Family MR Research Centre, Foothills Medical Centre, Calgary Health Region (S.B.C., J.E.S., A.I.T., J.R.M., R.F., A.M.D.), and Departments of Clinical Neurosciences (S.B.C., J.E.S., A.I.T., P.A.B., M.E.H., J.R.M., R.F., M.E., A.M.B., A.M.D.), Community Health Sciences (M.E.), and Radiology (J.C., M.E.H., J.R.M., R.F.), University of Calgary, Calgary, Alberta, Canada.