Objective To investigate the value of multiple sequential MRI in the differential diagnosis of vater ampulla carcinoma (VPC).Methods MRI data of 53 patients with VPC confirmed by surgery and pathology were analyzed retrospectively,which included 17ampullary carcinomas,15 pancreatic head carcinomas,10 duodenal papillary carcinomas and 11 distal common bile duct carcinomas.All patients underwent routine MRI plain scan,MRCP and multi-phase dynamic enhancement scan for the upper abdomen.The morphological characteristics and model of multi-phase dynamic enhancement of the tumor,and the morphological changes of pancreaticobiliary duct were focused,and relevant data were also measured.Results The differences of tumor size,central location,and signal homogeneity among the four different histological types showed statistical significance(P＜0.05),and their patterns of multi-phase dynamic enhancement also had differences.Double-segment sign was most found in VPC (26/53),four-segment sign was easy showed in pancreatic head carcinoma (8/15)and three-segment sign in distal common bile duct carcinoma (8/11).Beak sign was common seen in ampullary carcinoma(10/17),rat-tail sign was easy discovered in pancreatic head carcinoma (7/15) and truncated sign in distal common bile duct carcinoma(10/11).Diameter of major pancreatic duct in pancreatic head carcinoma was maximum and minimum in distal common bile duct carcinoma,and their difference had statistical significance(P＜0.05).Distance between obstructive end of bile common duct and major papilla of duodenum,and between obstructive end of major pancreatic duct and major papilla of duodenum as well as the pancreaticobiliary conjunction angle in pancreatic head carcinoma and distal common bile duct carcinoma were greater than that in ampullary carcinoma and duodenal papillary carcinoma.Conclusion MRI can prominently demonstrate various imaging characteristics of VPC with different histological origins.It is very valuable in the differential diagnosis of VPC with different histological types by comprehensive analysis of these findings.