1. From the Departments of Radiology (M.K., T.W.K., K.M.J., Y.K.K., S.H.K.), Pathology (S.Y.H.), and Internal Medicine (D.H.S.) and the Biostatics and Clinical Epidemiology Center (S.G.), Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Irwon-Dong, Gangnam-gu, Seoul 135-710, Republic of Korea.