Long-term outcomes of indeterminate focal hepatic observations less than 20 mm followed up with gadoxetic acid-enhanced magnetic resonance imaging (Gd-EOB-DTPA-MRI).

BACKGROUND

Indeterminate hepatic observations classified as Liver Imaging Reporting and Data System (LI-RADS) category 3 (LR-3) exhibit uncertain malignant potential and pose a diagnostic challenge during hepatocellular carcinoma (HCC) surveillance. Although most LR-3 observations remain stable, recent studies have reported variable progression rates to HCC. The purpose of the present study was to investigate and assess the clinical outcomes and progression-associated factors of LR-3 observations less than 20 mm in high-risk patients, on follow-up with serial gadoxetic acid-enhanced magnetic resonance imaging (Gd-EOB-MRI).

METHODS

A retrospective review was conducted on 125 patients with hepatitis B virus (HBV)-related cirrhosis who underwent Gd-EOB-MRI examinations at index and during follow-up. A total of 149 untreated LR-3 observations less than 20 mm in size were included in the study. Stepwise multivariate Cox proportional hazards model analysis was performed to identify the predictive risk factors for progression (upgraded to LR-4 or LR-5), including patient demographics and LI-RADS imaging features. Overall cumulative risk for progression was calculated using the Kaplan-Meier method, and significant predictive risk factors were compared using the log-rank test.

RESULTS

Over a median follow-up period of 18.3 months (range, 2.7-78.5 months), the overall cumulative risk of progression for LR-3 observations was 41.6% (62/149) and was 1.3%, 9.5%, 17.3%, and 37.3% at 3, 6, 12, and 24 months, respectively. The multivariate analysis revealed three significant independent predictors of progression: non-rim arterial phase hyperenhancement (APHE) [hazard ratio (HR) =2.19; P=0.005], subthreshold growth (HR =2.78; P=0.001), and mild-to-moderate T2 hyperintensity (HR =5.25; P<0.001). LR-3 observations with non-rim APHE or mild-to-moderate T2 hyperintensity showed a significantly higher cumulative risk of progression (53.3% 33.7% and 50.0% 28.8%, respectively; both P<0.001), as well as a shorter median interval to LR category upgrade (14.7 18.9 months and 15.1 26.5 months, respectively; both P<0.001), compared to those without these features.

CONCLUSIONS

Non-rim APHE, subthreshold growth, and mild-to-moderate T2 hyperintensity were significantly associated with an increased risk of progression among high-risk patients with LR-3 observations.. In particular, the presence of non-rim APHE or mild-to-moderate T2 hyperintensity was linked to both a higher cumulative incidence of progression and a shorter median interval to LR category upgrade.