1. From the Department of Radiology, University of Washington School of Medicine, Box 357115, 1959 NE Pacific St, Seattle, WA 98195 (J.M.X., D.S.H., M.Z., D.A.Z., L.M.C., G.V.T., M.K.D., R.B.O., W.P.S., C.L.W., A.M.); and Global Research Organization, GE Healthcare, Houston, Tex (A.G.C.).