1. Department of Endoscopy; Fukushima Medical University Hospital; Fukushima Japan
2. Department of Gastroenterology; Tokyo Women's Medical University Hospital; Tokyo Japan
3. Department of Gastroenterology; Fukushima Medical University Aizu Medical Center; Aizuwakamatsu Japan
4. Department of Gastroenterology and Rheumatology; Fukushima Medical University School of Medicine; Fukushima Japan