1 Division of Gastroenterology and Hepatology, Department of Internal Medicine, Institute of Gastrointestinal Medical Instrument Research, Korea University College of Medicine, Inchon-ro 73, Seongbuk-gu, Seoul 02841, Republic of Korea.
2 Division of Therapeutic Endoscopy, Department of Advanced Medicine, Research and Development Center for New Medical Frontiers, Kitasato University School of Medicine, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa 252-0374, Japan.
3 Division of Gastroenterology, Department of Internal Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 06591, Republic of Korea.
4 Edouard Herriot Hospital, Gastroenterology Unit, Pavillon L, 5 Place d'Arsonval, 69437 Lyon Cedex 03, France.