Interobserver and intermodality agreement of standardized algorithms for non-invasive diagnosis of hepatocellular carcinoma in high-risk patients: CEUS-LI-RADS versus MRI-LI-RADS

Objectives We compared the interobserver agreement for the recently introduced contrast-enhanced ultrasound (CEUS)-based algorithm CEUS-LI-RADS (Liver Imaging Reporting and Data System) versus the well-established magnetic resonance imaging (MRI)-LI-RADS for non-invasive diagnosis of hepatocellular carcinoma (HCC) in high-risk patients. MethodsFocal liver lesions in 50 high-risk patients (mean age 66.2 11.8 years; 39 male) were assessed retrospectively with CEUS and MRI. Two independent observers reviewed CEUS and MRI examinations, separately, classifying observations according to CEUS-LI-RADSv.2016 and MRI-LI-RADSv.2014. Interobserver agreement was assessed with Cohen's kappa. ResultsForty-three lesions were HCCs; two were intrahepatic cholangiocarcinomas; five were benign lesions. Arterial phase hyperenhancement was perceived less frequently with CEUS than with MRI (37/50 / 38/50 lesions = 74%/78% [CEUS; observer 1/observer 2] versus 46/50 / 44/50 lesions = 92%/88% [MRI; observer 1/observer 2]). Washout appearance was observed in 34/50 / 20/50 lesions = 68%/40% with CEUS and 31/50 / 31/50 lesions = 62%/62%) with MRI. Interobserver agreement was moderate for arterial hyperenhancement (k = 0.511/0.565 [CEUS/MRI]) and washout (k = 0.490/0.582 [CEUS/MRI]), fair for CEUS-LI-RADS category (k = 0.309) and substantial for MRI-LI-RADS category (k = 0.609). Intermodality agreement was fair for arterial hyperenhancement (k = 0.329), slight to fair for washout (k = 0.202) and LI-RADS category (k = 0.218) ConclusionInterobserver agreement is substantial for MRI-LI-RADS and only fair for CEUS-LI-RADS. This is mostly because interobserver agreement in the perception of washout appearance is better in MRI than in CEUS. Further refinement of the LI-RADS algorithms and increasing education and practice may be necessary to improve the concordance between CEUS and MRI for the final LI-RADS categorization. Key Points CEUS-LI-RADS and MRI-LIRADS enable standardized non-invasive diagnosis of HCC in high-risk patients.center dot With CEUS, interobserver agreement is better for arterial hyperenhancement than for washout.center dot Interobserver agreement for major features is moderate for both CEUS and MRI.center dot Interobserver agreement for LI-RADS category is substantial for MRI, and fair for CEUS. Interobserver-agreement for CEUS-LI-RADS will presumably improve with ongoing use of the algorithm.