1. From the Russell H. Morgan Department of Radiology and Radiologic Science (N.G., P.H.Y., K.C.), Sections of Body CT (E.K.F.) and Musculoskeletal Radiology (J.F.), Johns Hopkins Hospital, 601 N Caroline St, Room 3014, Baltimore, MD 21287; and Spine Division, Department of Orthopedics, Balgrist University Hospital Zurich, Zurich, Switzerland (M.F.).