1. Department of Gastroenterology and Hepatology, Uonuma Institute of Community Medicine Niigata University Hospital, Japan
2. Department of Diagnostic Radiology, National Cancer Center Hospital, Japan
3. Department of Gastroenterology and Hepatology, Nagaoka Central General Hospital, Japan
4. Division of Gastroenterology and Hepatology, Graduate School of Medical and Dental Sciences, Niigata University, Japan