Imaging findings and morphology classification of intraductal papillary mucinous neoplasm of the bile duct / 中华放射学杂志

ABSTRACT

Objective To investigate the CT and MRI features and morphology classification of intraductal papillary mucinous neoplasm of the bile duct (IPMN-B).Methods A total of 18 patients with IPMN-B proved by pathology were retrospectively analyzed.Out of 18 patients,16 patients underwent enhanced and non-enhanced CT,13 underwent contrast enhanced MR,and 11 out of 13 underwent both CT and MRI.IPMN-B was classified into 4 types:typical IPMN-B,cystic-forming IPMN-B,non-tumor IPMN-B and invasive IPMN-B,according to imaging findings and gross pathological findings.Results Typical IPMN-B (9 cases):tumors were distributed along the bile ducts,both upstream and downstream bile ducts were obviously dilated.Cystic-forming IPMN-B (5 cases):single or multiple tumors were found in aneurysmal dilatation of bile ducts.Non-tumor 1PMN-B (2 cases):no mass was found in the widely dilated bile ducts with smooth bile duct wall.Invasive IPMN-B (2 cases):tumors protruded into the dilated bile ducts causing jagged wall of bile duct,with accompanied abnormal density or signal intensity outside the bile ducts.Bile duct dilatations were shown in all 18 cases,and tumors were shown in 16 cases.In 2 cases no mass was displayed in widely dilated bile ducts.CT density of the tumor was lower than that of liver parenchyma,and higher than that of the bile and intraductal mucin.Signal intensity of the tumor was higher than that of stones,and lower than that of bile and intraductal mucin at MR T2WI.All tumors showed high intensity on DWI.Tumors showed mild to moderate enhancement after injection of contrast agent,CT density or signal intensity of the tumors were lower than that of the liver parenchyma during all three phases of contrast-enhanced CT or MRI.Conclusion IPMN-B has some specific CT and MR imaging features,which are helpful for the diagnosis and classification of IPMN-B.