Value of enhancing capsule for diagnosing hepatocellular carcinoma on MRI: implications for simplifying LI-RADS.

[OBJECTIVE] We evaluated the value of EC as a major feature for hepatocellular carcinoma (HCC) and its implications on simplifying LI-RADS v2018: by either excluding EC (LI-RADS[EC(-)]), or treating EC as equivalent to other major features (LI-RADS[EC(+)]).

[MATERIALS AND METHODS] This retrospective study included patients who underwent preoperative MRI within 1 month of surgery. Two radiologists independently assigned LI-RADS categories, with consensus resolution. The association between EC and HCC was evaluated by diagnostic odds ratio (DOR). Sensitivity and specificity of LI-RADS[EC(-)] and LI-RADS[EC(+)] were compared to LI-RADS v2018 using generalized estimating equations.

[RESULTS] Among 735 patients (median [interquartile range] age, 60 [54-66] years, 562 men) with 986 observations, 150 (20.4%) underwent extracellular contrast (ECA)-MRI and 585 (79.6%) underwent hepatobiliary contrast (HBA)-MRI. EC was significantly associated with HCC on both ECA-MRI (DOR = 16.6, p < 0.001) and HBA-MRI (DOR = 9.3, p < 0.001). LI-RADS[EC(+)] strategy demonstrated significantly higher sensitivity than LI-RADS v2018 on both ECA-MRI (81.3% vs. 78.4%, p = 0.047) and HBA-MRI (74.2% vs. 72.7%; p = 0.005), without significant differences in specificity (96.7% vs. 96.7%; p > 0.99 for ECA-MRI and 91.7% vs. 92.1%; p = 0.26 for HBA-MRI). However, LI-RADS[EC(-)] yielded a lower sensitivity (74.8% vs. 78.4%; p = 0.03 for ECA-MRI and 72.3% vs. 72.7%; p = 0.17 for HBA-MRI) without a gain in specificity.

[CONCLUSION] EC is strongly associated with HCC and critical for maintaining the sensitivity of the LI-RADS v2018. Treating EC as equivalent to other major features may simplify LI-RADS and improve sensitivity, particularly on ECA-MRI, where the increase in sensitivity was more pronounced than on HBA-MRI.

[KEY POINTS] Question Can LIRADS v2018 be simplified by considering enhancing capsule (EC) as equivalent to other major features (i.e., non-peripheral washout), regardless of observation size? Findings Treating EC as equivalent to other major features yielded higher sensitivity than LIRADS v2018 on both extracellular- and hepatobiliary contrast-enhanced MRI, without significantly compromising specificity. Clinical relevance EC is a key feature for hepatocellular carcinoma diagnosis. The strategy of treating EC as equivalent to other major features can be used to increase diagnostic sensitivity as well as simplify LI-RADS v2018, particularly on extracellular contrast-enhanced MRI.