Xiang-Lei Yuan1, Dan Yang2, Bing Hu3. 1. Department of Gastroenterology, West China Hospital, Sichuan University, No. 37 Guo Xue Alley, Wu Hou District, Chengdu City, 610041, Sichuan Province, China. 2. Department of Radiology, West China Hospital, Sichuan University, Chengdu, China. 3. Department of Gastroenterology, West China Hospital, Sichuan University, No. 37 Guo Xue Alley, Wu Hou District, Chengdu City, 610041, Sichuan Province, China. hubingnj@163.com.