1. Department of Gastroenterology, Yeouido St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
2. Department of Gastroenterology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
3. Department of Clinical Epidemiology and Biostatistics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
4. Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
5. Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea