Diagnostic performance of CT and MRI in distinguishing intraductal papillary neoplasm of the bile duct from cholangiocarcinoma with intraductal papillary growth

We aimed to evaluate the diagnostic performance of CT and MRI for distinguishing intraductal papillary neoplasm of the bile duct (IPNB) from cholangiocarcinoma (CC) with intraductal papillary growth (IPG). Forty-two patients with either IPNB or CC with IPG proven by histopathology were independently reviewed in retrospect. Strict criteria for diagnosis of IPNB included presence of the designated imaging features as follows: local dilatation of the bile duct, nodule within the dilated bile duct, growing along the interior wall of bile duct. Any lesion that was not consistent with the criteria was classified as CC with IPG. Sensitivity, specificity, positive and negative predictive values for characterization of IPNB were calculated, and k test was used to assess the level of agreement. Two imaging reviewers correctly identified 21 of 26 (80.8 %) and 22 of 26 (84.6 %) IPNB cases, respectively. Alternatively, they correctly identified 14 of 16 (87.5 %) and 15 of 16 (93.8 %) CC with IPG, respectively. Agreement between the two reviewers was perfect (k = 0.81) for the diagnosis of IPNB and differentiation from CC with IPG. By using our designated diagnostic criteria of CT and MRI, IPNB can be accurately identified and possible to be distinguished from CC with IPG. aEuro cent IPNB can accurately be identified by using defined diagnostic criteria at CT/MRI. aEuro cent IPNB has some characteristic CT and MR imaging features. aEuro cent IPNB is a rare entity; up until now it might have been misdiagnosed.