1. From the Departments of Radiology (D.H.L., J.M.L., J.K.H.) and Internal Medicine (J.H.Y., Y.J.K.), Seoul National University Hospital, 101 Daehangno, Jongno-gu, Seoul 110-744, Korea; Department of Radiology, Seoul National University College of Medicine, Seoul, Korea (D.H.L., J.M.L., J.K.H.); and Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea (J.M.L., J.K.H.).