1. From the Department of Radiology, MedStar Georgetown University Hospital, 3800 Reservoir Rd NW, CCC Building Ground Floor, CG 201, Washington, DC 20007 (N.K., M.A.M.); the Joint Pathology Center, Silver Spring, Md (A.A.); and the American Institute for Radiologic Pathology, Silver Spring, Md (M.A.M.).