1. Department of Endoscopy, Nagasaki University Hospital, Nagasaki, Japan
2. Department of Gastroenterology and Hepatology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
3. Medical Education Development Center, Nagasaki University Hospital, Nagasaki, Japan
4. Department of Histology and Biomedical Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
5. Department of Gastroenterology, Inoue Hospital, Nagasaki, Japan