1. From the Department of Radiology, Duke University Hospital, 2301 Erwin Rd, Durham, NC 27701 (B.W.T., M.B., J.K.H., R.G.S., M.A.M.); Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (W.D.M., D.T.); and Department of Radiology, University of Alabama at Birmingham, Birmingham, Ala (F.N.T.).