1. From the Duke University School of Medicine, Durham, NC (K.K.); Department of Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 559905 (P.J.N., S.K.V., P.S.R.); Mallinckrodt Institute of Radiology, Washington University, St. Louis, Mo (M.I.); and Mayo Clinic, Jacksonville, Fla (A.K.A.).