1. National Clinical Research Center for Digestive Diseases and Xijing Hospital of Digestive Diseases Fourth Military Medical University Xi'an China
2. Department of Radiology, Xijing Hospital Fourth Military Medical University Xi'an China
3. Department of General Surgery First Affiliated Hospital of Xian Jiaotong University Xi'an China
4. Department of Digestive Disease and Yale Center for Pancreatic Disease Yale School of Medicine New Haven Connecticut USA