Computed tomography features of an intraductal polypoid mass: differentiation between hepatocellular carcinoma with bile duct tumor invasion and intraductal papillary cholangiocarcinoma.

OBJECTIVE

To determine the computed tomography (CT) features capable of differentiating hepatocellular carcinoma (HCC) with bile duct tumor invasion (BDTI) from intraductal cholangiocarcinoma (IDCC).

METHODS

Multiphasic CT images of 14 patients with HCC with BDTI and 18 patients with IDCC were retrospectively reviewed. Analysis of the CT findings included the size, location, and margin of the intraductal mass; enhancement pattern of intraductal lesions; degree of ductal dilatation; presence of downstream ductal dilatation and ductal wall thickening; presence of a parenchymal mass and its size; continuity of the parenchymal mass with the intraductal mass; and liver cirrhosis. Objective evaluation of the enhancement patterns of intraductal tumors was done by measuring the CT attenuation coefficients of the tumors and the uninvolved hepatic parenchyma in each phase. Among these findings, statistically significant variables were then determined using the Fisher's exact test or Mann-Whitney U test.

RESULTS

Significant variables that helped to differentiate HCC with BDTI from IDCC included the presence of a parenchymal mass, liver cirrhosis, and a hyperattenuating intraductal tumor on the hepatic arterial phase (HAP). On unenhanced images, the tumor-to-liver contrast of IDCC (16.7+/-8.1) was greater than that of HCC with BDTI (6.4+/-10.4), but on the HAP, that of HCC with BDTI (26.5+/-28.2) was greater than that of IDCC (5.9+/-18.7) (P<0.05). In addition, there was a significant difference in the enhancement ratio of the intraductal tumors on the portal venous phase between the 2 conditions (P=0.003).

CONCLUSIONS

Several objective and subjective multiphasic CT findings may help to differentiate HCC with BDTI from IDCC.