1. Department of Radiology, Peking University People's Hospital, 11 Xizhimen S St, Beijing 100044, China
2. Department of Medical Oncology, Cancer Center, West China Hospital of Sichuan University, Chengdu, China
3. Department of Pathology, Peking University People's Hospital, Beijing, China
4. Department of Gastrointestinal Surgery, Peking University People's Hospital, Beijing, China