1. Department of Gastroenterology, Beijing Friendship Hospital, Capital Medical University, National Clinical Research Center for Digestive Disease, Beijing Digestive Disease Center, Beijing Key Laboratory for Precancerous Lesion of Digestive Disease, Beijing, China
2. Department of Gastroenterology, Digestive Endoscopy Unit, Tongliao City Hospital, Tongliao, China
3. Department of General Surgery, Tongliao City Hospital, Tongliao, China
4. Department of Anesthesia, Beijing Friendship Hospital, Capital Medical University, Beijing, China