1. Department of Gastroenterology, The Sixth Affiliated Hospital, Sun Yat-sen University , Guangzhou , P.R. China
2. Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University , Guangzhou , P.R. China
3. Biomedical Innovation Center, The Sixth Affiliated Hospital, Sun Yat-sen University , Guangzhou , P.R. China
4. Departments of Medical Ultrasonics, The Sixth Affiliated Hospital, Sun Yat-sen University , Guangzhou , P.R. China