1. From the Department of Radiology and Research Institute of Radiology (D.W.K., S.S.L., J.H.K., H.J.K., J.H.B.), Department of Clinical Epidemiology and Biostatistics (S.O.K.), Department of Oncology (C.Y., K.P.K.), and Department of Surgery (K.B.S., S.C.K.), University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43-Gil, Songpa-Gu Seoul, Seoul 138-736, Republic of Korea.