1. From the Department of Radiology and Research Institute of Radiological Science (S.H.P., J.S.L., M.S.P., M.J.K., H.K.); Biostatistics Collaboration Unit (J.L., H.Y.K.); Department of Radiation Oncology (W.S.K.); and Department of Surgery, Division of Colon and Rectal Surgery (H.H.); Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea.