1. Department of Gastroenterology and Hepatology; National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku; Tokyo 162-8655 Japan
2. Department of Radiology; National Center for Global Health and Medicine; Tokyo Japan
3. Department of Gastroenterology; Saga Medical School; Saga Japan
4. Kohnodai Hospital; Chiba Japan