1. From the Departments of Radiology (C.S., B.P., S.H., P.D., R.C.N., D.M.) and Biostatistics and Bioinformatics (A.E.F.), Duke University Medical Center, Box 3808 Erwin Rd, Durham, NC 27710; Department of Diagnostic and Interventional Radiology, University Hospital of Tuebingen, Tuebingen, Germany (C.S., K.N.); and Department of Computed Tomography, Siemens Medical Solutions USA, Malvern, Pa (J.C.R.).