1. Department of Diagnostic Radiology, Yokohama City University Graduate School of Medicine, Yokohama 236-0004, Japan
2. Department of Gastroenterology and Hepatology, Yokohama City University Graduate School of Medicine, Yokohama 236-0004, Japan
3. Department of Interventional Radiology, Saiseikai Yokohama Nanbu Hospital, Yokohama 234-0054, Japan
4. Department of Gastroenterology, Sanno Hospital, Tokyo 107-0052, Japan