1. Department of Gastroenterology and Neurology, Faculty of Medicine, Kagawa University, Kita-gun 761-0793, Japan
2. Department of Internal Medicine, HITO Medical Center, Shikokuchuo 799-0121, Japan
3. Department of Gastroenterology and Hepatology, Takamatsu Red Cross Hospital, Takamatsu 760-0017, Kagawa, Japan
4. Department of Radiology, Kagawa University, Kita-gun 761-0793, Japan