Added value of ancillary imaging features for differentiating scirrhous hepatocellular carcinoma from intrahepatic cholangiocarcinoma on gadoxetic acid-enhanced MR imaging.

OBJECTIVES: To determine ancillary features that help distinguish between scirrhous hepatocellular carcinoma (S-HCC) and intrahepatic cholangiocarcinoma (ICC) and investigate added value of ancillary features to enhancement pattern-based diagnosis on gadoxetic acid-enhanced MRI.

METHODS: This retrospective study included 96 patients with S-HCCs and 120 patients with ICCs who underwent gadoxetic acid MRI before surgical resection. Two observers reviewed MRIs of the tumours. After determining ancillary features for differentiating tumour types, we measured the diagnostic performance of adding ancillary features to enhancement pattern-based diagnosis.

RESULTS: T2 central darkness, capsule and septum were significant and independent features differentiating S-HCC from ICC (p ≤ .06). Adding ancillary features to enhancement pattern led to increased accuracy (observer 1, 78.9 vs. 93.8 %; observer 2, 80.3 vs. 92.8 %; p < .001), sensitivity (observer 1, 74.5 vs. 96.4 %; observer 2, 77.1 vs. 93.2 %; p < .001 and .001), and specificity (observer 1, 82.5 vs. 91.7 %; observer 2, 82.9 vs. 92.5 %; p = .006 and .005) for diagnosis of S-HCC by differentiation from ICC.

CONCLUSIONS: Adding ancillary features capsule, septum and T2 central darkness to conventional enhancement patterns on gadoxetic acid-enhanced MRI improved accuracy, sensitivity and specificity for S-HCC diagnosis with differentiation from ICC.

KEY POINTS: • Capsule, septum, and T2 central darkness were ancillary features for S-HCC. • A typical HCC enhancement was seen in 31.3% of S-HCCs. • Ancillary MRI features were useful in differentiation between S-HCC and ICC.