The Functional Liver Imaging Score (FLIS), derived from gadoxetic acid–enhanced MRI, is a reproducible and non-invasive tool for assessing hepatic function in chronic liver disease (CLD). Our findings demonstrated that while FLIS scores were significantly associated with clinical severity, the moderate effect size suggests its role is complementary rather than standalone in clinical evaluation. These findings suggest that FLIS can complement established laboratory indices such as FIB-4 in assessing liver disease burden.
Our findings showed that both FLIS and FIB-4 scores significantly differed across Child–Pugh classes, with FLIS scores being higher in Class A, although FIB-4 significantly differed across Child–Pugh classes. These results align partially with Lee et al., who reported strong correlations between FLIS and Child–Pugh scores, and supported FLIS as a reliable stratification tool for hepatic function and decompensation risk [14]. However, similar to Zou et al., who observed only moderate correlations and identified spleen size and SPSS as stronger predictors of decompensation, our findings also emphasized that FIB-4 and spleen size showed greater discriminatory power than FLIS [18]. This suggests that while FLIS reflects hepatic function, its performance may vary depending on disease stage and structural parameters, and may be less sensitive in advanced fibrosis or portal hypertension contexts.
Validation studies by Bastati et al. and Lee et al. showed strong correlations between FLIS and clinical severity scores like Child–Pugh and MELD, and its value in predicting outcomes such as decompensation and mortality [13, 14]. Similarly, FLIS was shown to predict graft survival in liver transplant patients [4]. Our findings support these results, as we also found a significant correlation between FLIS and both Child–Pugh class. This suggests FLIS is useful for assessing liver function in a broader CLD population, not just in advanced or surgical cases.
Impaired biliary excretion of gadoxetic acid has been identified as a strong predictor of mortality in previous work [3]. In our study, however, only parenchymal enhancement demonstrated significant association with Child–Pugh scores, whereas biliary excretion and portal vein signs did not show significant correlation. These differences may be attributable to heterogeneity of the study population and inclusion of earlier disease stages, where biliary impairment is less prominent.
FLIS has previously been shown to predict postoperative liver failure and graft survival after transplantation[4]. Our study, however, focused on non-surgical CLD subgroups, limiting direct comparison with surgical or transplant populations. Still, these findings emphasize the broader relevance of FLIS in liver function assessment and perioperative risk stratification.
Most previous studies evaluated FLIS in patients with advanced cirrhosis or transplant candidates. In contrast, our cohort included a broader range of CLD etiologies such as viral hepatitis and NASH, spanning various stages of disease. This heterogeneity may explain why FLIS was less consistent in reflecting severity, particularly in early-stage cases. Effect size analysis showed that FIB-4 and spleen size had strong discriminatory power, supporting their value in assessing fibrosis and portal hypertension. Although FLIS demonstrated statistical significance, the effect size was moderate, indicating it may be less discriminative, especially in early-stage or compensated disease.
Recent expert statements, including Baveno VII and the 8th International Forum on Liver Imaging, highlight the potential of gadoxetic acid–enhanced MRI in non-invasive liver function assessment, while also emphasizing the need for further validation before clinical integration [1]. Our findings support this view, suggesting that FLIS performance may vary based on patient characteristics and disease stage.
A recent meta-analysis confirmed that FLIS and its subcomponents have excellent inter-reader reliability, regardless of MRI technique or reader experience [19]. This supports FLIS as a reproducible imaging tool. In our study, while total FLIS scores correlated with clinical severity, hepatobiliary parenchymal enhancement stood out as the most informative subcomponent. This suggests that individual FLIS parameters may better reflect liver function than the composite score alone, especially in heterogeneous CLD populations.
Eryuruk et al. demonstrated that the Relative Enhancement Index (REI) derived from gadoxetic acid-enhanced MRI outperformed FLIS in predicting ALBI grades, showing stronger correlations and higher diagnostic accuracy[20]. Consistently, our findings suggest that conventional indices such as FIB-4 may better reflect disease severity in heterogeneous CLD populations. RLE values were highest in patients with non-advanced CLD and showed inverse correlations with FIB-4 and spleen size, further underscoring its potential functional relevance. These findings indicate that RLE, as a quantitative imaging parameter, may provide valuable functional insight—potentially exceeding composite visual scores like FLIS in certain clinical contexts.
Aslan et al. reported very strong correlations between FLIS (and its subcomponents) and ALBI grades, along with excellent intra- and inter-observer agreement, confirming its reproducibility in clinical practice [10]. Consistent with these findings, our study demonstrated a significant association between total FLIS scores and clinical severity indicators such as Child-Pugh class and FIB-4 category. Among the individual FLIS components, hepatobiliary parenchymal enhancement remained the most informative, supporting its particular relevance in non-invasive liver function assessment.
While the prognostic value of FLIS has been widely recognized in the literature, our results further support its utility by demonstrating a significant correlation between FLIS and clinical severity in patients with chronic liver disease. However, it is important to note that in heterogeneous populations—especially those including patients at earlier disease stages—FLIS alone may not fully capture the complexity of liver dysfunction. Therefore, FLIS should be interpreted alongside established clinical and laboratory parameters to ensure a more comprehensive assessment of hepatic function.
Our results showed that higher FIB-4 categories were significantly associated with disease severity, consistent with previous reports highlighting its utility as a non-invasive marker of advanced fibrosis [17]. The positive correlation between FIB-4 and spleen size further reflects its link to portal hypertension, while the absence of significant associations with RLE and LSI suggests that imaging-derived parameters capture different functional aspects. The observed negative correlation between spleen size and RLE, and positive correlation between RLE and LSI, support prior findings that gadoxetic acid–enhanced MRI primarily reflects parenchymal function rather than structural changes [10, 20]
This study is subject to several limitations. Its retrospective design and single-center setting may limit generalizability. Although the sample size was relatively robust, power for certain subgroup analyses remains limited. Additionally, we did not assess long-term outcomes such as hepatic decompensation, transplant-free survival, or mortality—parameters that have been used in prior FLIS validation studies to demonstrate prognostic value.