Diagnostic performance of liver imaging reporting and data system ancillary features for hepatocellular carcinoma: a systematic review and evidence synthesis.

OBJECTIVE: To systematically review and evaluate the evidence supporting the role of Liver Imaging Reporting and Data System (LI-RADS) ancillary features (AFs) in optimizing hepatocellular carcinoma (HCC) diagnosis across magnetic resonance imaging (MRI), computed tomography (CT), and contrast-enhanced ultrasound (CEUS) modalities, with a focus on their incremental value in specific clinical scenarios. METHODS: A comprehensive literature search was performed across PubMed and Embase from 2011 to 2024 to identify studies on LI-RADS AFs. Significant ancillary features (SAFs)-a review-specific descriptive framework rather than an official LI-RADS category-were defined as features demonstrating a statistically significant contribution to HCC diagnosis or LI-RADS diagnostic performance in at least one included study (p < 0.05). RESULTS: A total of 101 articles were included. In terms of imaging modality distribution, MRI was predominant (91.1%, 92/101), while CT (21.8%, 22/101) and CEUS (9.9%, 10/101) studies were relatively limited. For LI-RADS categories LR-1 to LR-5, fourteen SAFs were identified on MRI (e.g., hepatobiliary phase hypointensity, diffusion restriction). For lesions ≤ 3 cm, the incremental value of applying a single guideline-recommended AF was marginal. In contrast, applying combinations of ≥ 4 AFs significantly improved sensitivity by 10.6-18.3% without a significant loss of specificity. Evidence for CT-based AFs was limited and inconsistent. For CEUS LR-1 to LR-5 observations, six AFs were identified, with exploratory markers showing potential incremental value, whereas the two official AFs showed inconsistent performance. For LR-M lesions, 14 SAFs significantly contributed to differentiating HCC from other hepatic malignancies (p < 0.05). In treatment response assessment (TRA), five SAFs-two of which are guideline-recommended-improved diagnostic sensitivity by 3.2-42.8% without loss of specificity. CONCLUSION: LI-RADS AFs enhance HCC diagnostic accuracy when complementing major features, with the most robust evidence supporting MRI-based AFs. In contrast, AFs based on CT and CEUS require further validation.