1. Division of Gastroenterology, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
2. Division of Gastroenterology, Department of Internal Medicine, Wonju Severance Christian Hospital, Yonsei University Wonju College of Medicine, Wonju, Korea.
3. Department of Surgery, Yeonsei Hangmac Hospital, Goyang, Korea.
4. Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
5. Department of Pathology, International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, Korea.