LI-RADS ancillary features favoring benignity: is there a role in LR-5 observations?

Objectives The Liver Imaging Reporting and Data System algorithm allows category downgrade in the presence of ancillary features (AFs) favoring benignity, even in observations categorized as LR-5. This study aims to assess the role of AFs favoring benignity in LR-5 observations and their impact on category downgrade. Methods This study included high-risk patients with at least one LR-5 observation imaged with gadoxetate disodium MRI. Three readers with different experience levels independently evaluated the presence of AFs favoring malignancy (not hepatocellular carcinoma (HCC) in particular and HCC in particular) and AFs favoring benignity. Category downgrade was considered possible in the presence of >= 1 AF favoring benignity and no AF favoring malignancy. Correlation between observations size and number of AFs was assessed using Spearman's rank correlation coefficient. Cohen's kappa (k) test was used to assess inter-reader agreement. Results The final study cohort included 162 LR-5 (mean size: 23 +/- 16 mm) in 119 patients. AFs favoring benignity were reported in 9 (5.6%), 20 (12.3%), and 10 (6.2%) LR-5 observations by reader 1, reader 2, and reader 3, respectively. Hepatobiliary phase isointensity was observed in 6 (3.7%), 2 (1.2%), and 7 (4.3%) observations, respectively. Category downgrade was considered possible in only one (0.6%) observation by reader 1 and reader 3. There was a significant correlation between observation size and number of AFs favoring malignancy (p < 0.001), not HCC in particular (p <= 0.010), and favoring HCC in particular (p < 0.001). Inter-reader agreement of AFs favoring benignity was poor to moderate (k range: - 0.01, 0.43). Conclusions AFs favoring benignity are not uncommon in LR-5 observations, but category downgrade is exceptional.