1. Department of Internal Medicine, Division of Gastroenterology, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 665, Bupyeong-dong, Bupyeong-gu, Incheon 403-720, Seoul, Korea.
2. Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Internal Medicine, CHA Bundang Medical Center, CHA University, Seongnam, Korea.
4. Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
5. Department of Surgery, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.