Differentiation of mass-forming intrahepatic cholangiocarcinoma from poorly differentiated hepatocellular carcinoma: based on the multivariate analysis of contrast-enhanced computed tomography findings.

PURPOSE: We aim to gain further insight into identifying differential radiological features of mass-forming intrahepatic cholangiocarcinoma (mICC) from poorly differentiated hepatocellular carcinoma (pHCC) on contrast-enhanced computed tomography (CT).

MATERIALS AND METHODS: 107 patients with pathologically confirmed mICC (n = 48) and pHCC (n = 59) who had undergone preoperative contrast-enhanced CT were enrolled. Qualitative analysis of CT images were evaluated for tumor demarcation, shape, presence of satellite nodules, capsular retraction, biliary involvement, intratumoral arteries, tortuous tumoral vessels, vascular invasion, portal vein tumor thrombus, arterial enhancement pattern, portal venous phase enhancement, and washout pattern. Quantitative analysis was performed for mean attenuation of tumor and tumor-to-liver contrast during each phase. The degree of arterial enhancement was graded based on quantitative measurements.

RESULTS: A lobulated shape, indistinct margin, peripheral rim enhancement in the arterial phase, and the presence of bile duct dilatation were CT features favoring mICC, whereas a round shape, partially indistinct margin, heterogeneous enhancement in the arterial phase, washout pattern and the presence of tortuous tumoral vessels were CT features favoring pHCC in the univariate analysis (P < 0.05). Tumor-to-liver contrast of pHCC was greater than that of mICC during the arterial phase (P = 0.015). In the multivariate analysis, bile duct dilatation, tortuous tumoral vessels, and a washout pattern were independent CT features for distinguishing between the two types. (P = 0.003, P = 0.003, P = 0.044, respectively).

CONCLUSION: The absence of a washout pattern and tortuous tumoral vessels and presence of bile duct dilatation are more indicative of mICC than of pHCC on contrast-enhanced CT.