Differentiating combined hepatocellular and cholangiocarcinoma from mass-forming intrahepatic cholangiocarcinoma using gadoxetic acid-enhanced MRI

Purpose: To examine the differential features of combined hepatocellular and cholangiocarcinoma (HCC-CC) from mass-forming intrahepatic cholangiocarcinoma (ICC) on gadoxetic acid-enhanced MRI. Materials and Methods: Forty patients with pathologically proven combined HCC-CC (n = 20) and ICCs (n = 20) who had undergone gadoxetic acid-enhanced MRI were enrolled in this study. MR images were analyzed for the shape of lesions, hypo- or hyperintense areas on the T2-weighted image (T2WI), rim enhancement during early dynamic phases, and central enhancement with hypointense rim (target appearance) on the 10-min and 20-min hepatobiliary phase (HBP). The significance of these findings was determined by the χ² test. Results: Irregular shape and strong rim enhancement during early dynamic phases, and absence of target appearance on HBP favored combined HCC-CCs (P < 0.05). Lobulated shape, weak peripheral rim enhancement, and the presence of complete target appearance on the 10-min and 20-min HBP favored ICCs (P < 0.05). However, 10 CC-predominant type of combined HCC-CC showed complete or partial target appearance on 10-min HBP. Conclusion: The shape of tumors, degree of rim enhancement during early dynamic phases, and target appearance on HBP were valuable for differentiating between combined HCC-CC and mass-forming ICC on gadoxetic acid-enhanced MRI.