1. Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan
2. Department of Gastroenterology, Tsuyama Chuo Hospital, Tsuyama, Japan
3. Department of Endoscopy, Okayama University Hospital, Okayama, Japan
4. Department of Pathology, Okayama University Hospital, Okayama, Japan