1. From the Department of Radiology (S.P., I.J., D.H.L., J.S.B., J.Y., S.W.K., J.M.L.) and Institute of Radiation Medicine, Seoul National University Medical Research Center (J.M.L.), Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea; and Department of Radiology, Seoul National University College of Medicine, Seoul, Korea (S.P., I.J., D.H.L., J.S.B., J.Y., S.W.K., J.M.L.).