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