1. Center for Diagnostic and Therapeutic Endoscopy, School of Medicine, Keio University, Tokyo, Japan
2. Digestive Disease Center, Showa University Northern Yokohama Hospital, Yokohama, Japan
3. Departments of Endoscopy, Tokyo Medical and Dental University, Tokyo, Japan apan
4. Center for Gastroenterology and Inflammatory Bowel Disease, Ofuna Chuo Hospital, Kamakura, Japan
5. Division of Gastroenterology and Hepatology, Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan
6. Department of Gastroenterology, Fujigaoka Hospital, Showa University, Yokohama, Japan