Shuichi Miyamoto1,2, Kazuhiro Takahashi3, Tomohiko R Ohya4. 1. Department of Gastroenterology and Hepatology, Hakodate Municipal Hospital, Hokkaido, Japan. 2. Department of Gastroenterology and Hepatology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Hokkaido, Japan. 3. Department of Gastroenterology and Hepatology, Medical Topia Soka Hospital, Saitama, Japan. 4. Department of Endoscopy, The Jikei University School of Medicine, Tokyo, Japan.