1 From the Department of Radiology, University of Maryland Medical Center, 22 S Greene St, Baltimore, MD 21201 (O.A.A.); Division of Diagnostic Imaging and Radiology, Children's National Hospital, George Washington School of Medicine, Washington, DC (J.S.K.); and Department of Radiology, Johns Hopkins Hospital, Baltimore, Md (A.C.Y., J.K.S.).