1. From the Department of Radiology, Research Institute of Radiology (A.R.P., E.Y.C., J.H.C., H.J.S., W.J.C., H.H.K.), and Department of Clinical Epidemiology and Biostatistics (H.J.K.), Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-Gil, Songpa-Gu, Seoul 05505, South Korea.