1. Department of Health Care Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki city, Okayama 701-0192, Japan
2. Division of Endoscopy and Ultrasonography, Department of Clinical Pathology and Laboratory Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki city, Okayama 701-0192, Japan
3. Department of Internal Medicine, Tsuyama Chuo Hospital, 1756 Kawasaki, Tsuyama, Okayama 708-0841, Japan
4. Department of Gastroenterology, Okayama University Hospital, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan
5. Department of General Internal Medicine 2, Kawasaki Medical School, 577 Matsushima, Kurashiki city, Okayama 701-0192, Japan