Purpose: To assess the added value of intratumoral ancillary features to conventional enhancement pattern-based diagnosis of hepatocellular carcinoma (HCC) on gadoxetic acid-enhanced magnetic resonance imaging (MRI).
Materials and methods: A total of 773 consecutive patients with surgically resected 773 primary hepatic tumors (699 HCCs, 63 intrahepatic cholangiocarcinomas, and 11 benign nodules) who underwent gadoxetic acid-enhanced MRI were retrospectively identified. Enhancement patterns and three ancillary features of capsule, septum, and T2 spotty hyperintensity were assessed by two radiologists. Performance of enhancement pattern-based diagnosis of HCC was compared to diagnosis of HCC based on enhancement pattern plus ancillary features.
Results: Enhancement patterns were positive (arterial diffuse hyperenhancement with washout) for 562 (72.7%) tumors, negative (no arterial hyperenhancement and no washout) for 75 (9.7%), and inconclusive (either no arterial hyperenhancement or no washout) for 136 (17.6%). Capsule was observed in 498 (64.4%) tumors, septum in 521 (67.3%), and T2 spotty hyperintensity in 107 (13.8%). The accuracy and sensitivity of HCC diagnosis was improved significantly after adding at least one ancillary feature compared with enhancement pattern-based diagnosis of HCCs (79.9% vs. 91.1% for accuracy, p < 0.0001 and 79.1% vs. 92.0% for sensitivity, p < 0.0001) with a minor tradeoff in specificity (87.8% vs. 82.4%, p = 0.125). Adding at least two ancillary features improved accuracy (88.1%, p < 0.0001) and sensitivity (88.1%, p < 0.0001) without changing specificity (87.8%, p = 1.0).
Conclusion: Adding intratumoral ancillary features of capsule, septum and T2 spotty hyperintensity to conventional enhancement patterns on gadoxetic acid-enhanced MRI improved accuracy and sensitivity, while maintaining specificity for HCC diagnosis.
Keywords: Ancillary feature; Diagnosis; Enhancement; Hepatocellular carcinoma; Magnetic resonance imaging.