1. Division of Gastroenterology, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei 11490, Taiwan
2. Department of Radiation Oncology, Tri-Service General Hospital, National Defense Medical Center, Taipei 11490, Taiwan
3. Division of Organ Transplantation Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei 11490, Taiwan
4. Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei 11490, Taiwan
5. Gastrointestinal Unit, Massachusetts General Hospital, Harvard Medical School, Warren 1019A, 55 Fruit Street, Boston, MA 02114, USA