Differentiation of confluent hepatic fibrosis and mass forming intrahepatic cholangiocarcinoma with infltrative tumor margin (mICCITM) on MR imaging

To identify potential magnetic resonance imaging (MRI) features that can differentiate confluent fibrosis (CF) from mass forming intrahepatic cholangiocarcinoma with an infltrative tumor margin (mICCITM). A retrospective analysis was conducted on 44 CF patients and 30 mICCITM patients who underwent upper abdomen MRI scans. The imaging features of lesions were analyzed, and the apparent diffusion coefficient (ADC) values of lesions were measured. Accuracy, sensitivity and specificity for the diagnosis of CF were calculated for each MRI feature individually and in combination. Hepatic capsular retraction at the site of the lesion, hepatic volume loss, the “nodular surround sign,” and liver cirrhosis were more common in CF patients compared to mICCITM patients (all P < 0.005). When hepatic capsular retraction, non-enhancement or non-rimenhancement in arterial phase, and delayed phase signal homogeneity showed superior diagnostic accuracy (75.7% (56/74), 79.7% (59/74) and 94.6% (70/74), respectively). When hepatic capsular retraction, nonenhancement or nonrimenhancement in arterial phase or signal homogeneity in delayed phase, a sensitivity of 100.0% (44/44) for the diagnosis of CF was achieved. A specificity of 96.7% (29/30) was achieved when hepatic capsular retraction and signal homogeneity in the delayed phase, or nonenhancement or nonrimenhancement in the arterial phase and signal homogeneity in the delayed phase, or all three features were positive. The combination of nonenhancement or nonrimenhancement in the arterial phase and signal homogeneity in the delayed phase demonstrated 97.7% (43/44) sensitivity, 96.7% (29/30) specificity, and 97.3% (72/74) accuracy for CF diagnosis, with the AUC was 0.972 (95% CI: 0.904–0.996). No significant difference was observed in the ADC values of lesions between CF and mICCITM (p = 0.511). The combination of nonenhancement or nonrimenhancement in arterial phase and delayed phase signal homogeneity are potential MRI features for differentiating CF from mICCITM. 1. The imaging features of CF may mimic intrahepatic cholangiocarcinoma (ICC). 2. The combination of arterial nonenhancement or nonrimenhancement and signal homogeneity in the delayed phase demonstrated 97.7% sensitivity, 96.7% specificity, and 97.3% accuracy for CF diagnosis, with the AUC was 0.972 (95% CI: 0.904–0.996). 3. The combination of nonenhancement or nonrimenhancement in arterial phase and delayed phase signal homogeneity are potential MRI features for differentiating CF from mICCITM.