[1] Keio Univ, Dept Internal Med, Div Gastroenterol & Hepatol, Sch Med,Shinjuku Ku, Tokyo 1608582, Japan
[2] Keio Univ, Sch Med, Ctr Diagnost & Therapeut Endoscopy, Tokyo, Japan
[3] Keio Univ, Sch Med, Dept Diagnost Radiol, Tokyo, Japan
[4] Keio Univ, Sch Med, Dept Surg, Tokyo 160, Japan