Differentiating mass-forming intrahepatic cholangiocarcinoma from atypical hepatocellular carcinoma using gadoxetic acid-enhanced MRI

Aim: To examine the differential features of mass-forming intrahepatic cholangiocarcinoma (ICC) from atypical hypovascular hepatocellular carcinoma (HCC) on gadoxetic acid-enhanced magnetic resonance imaging (MRI). Materials and methods: The institutional review board approved this retrospective study and waived informed patient consent. Seventy patients with pathologically proven ICCs (35) and hypovascular atypical HCCs (35) who had undergone preoperative gadoxetic acid-enhanced MRI were enrolled in this study. Images were analysed for the shape of the lesions and presence of hyperintensity on the T1-weighted image (T1WI) and hypo- or hyperintense areas on the T2-weighted image (T2WI). In addition, images were analysed for the presence of linear hyperintensity or multifocal, tiny, hyperintense foci on T2WI and the presence of rim enhancement during early dynamic phases and a central enhancement with a hypointense rim (target appearance) on the 10 and 20 min hepatobiliary phase images. The significance of these findings was determined by the X² test. Results: Univariate analysis revealed that the following significant parameters favour ICC or hypovascular HCC; the presence of T2 hypo- and hyperintense areas and target appearance on the 10 min hepatobiliary phase images favour ICC, and the presence of T2 linear hyperintensity and T2 multifocal hyperintense foci favour hypovascular HCC (p < 0.05). Multivariate analysis revealed that only target appearance on the 10 min hepatobiliary phase was predictive of ICC (p = 0.002) as 30 ICCs (85.7%) showed this feature. However, the target appearance was also observed in all six scirrhous HCCs. Conclusion: A target appearance on the 10 min hepatobiliary phase images is the best predictor for identifying mass-forming ICC at gadoxetic acid-enhanced MRI.