[1] Univ Ulsan, Dept Diagnost Radiol, Asan Med Ctr, Songpa Ku, Seoul 138736, South Korea
[2] Univ Ulsan, Asan Med Ctr, Dept Gastroenterol, Seoul 138741, South Korea
[3] Univ Ulsan, Asan Med Ctr, Dept Gen Surg, Seoul 138741, South Korea
[4] Sungshin Womens Univ, Dept Stat, Seoul, South Korea
[5] Siemens Ltd, Asia Prod Ctr, Hong Kong, Peoples R China