MRI-derived extracellular volume to assess liver fibrosis in patients with metabolic-associated steatotic liver disease.

Purpose: Metabolic associated steatotic liver disease (MASLD) is the most prevalent chronic liver disease, and non-invasive fibrosis staging still represents a challenge. Our main objective was to estimate the degree of liver fibrosis in these patients using T1 mapping and the extracellular volume (ECV) by MRI in comparison with liver stiffness assessed by MR elastography (MRE).

Methods: In a single-center cross-sectional study, patients with MASLD were prospectively enrolled and underwent MRI with liver T1 mapping and ECV calculations. Groups with and without significant liver fibrosis assessed by MRE were compared with the Mann-Whitney test, chi-square test, and Fisher's exact test. Correlation analysis was conducted using Spearman's test, and a receiver operating characteristic (ROC) curve was generated to assess the ability of ECV to differentiate between groups.

Results: This study evaluated 54 patients, 37% were men, with a mean age of 58.0 ± 12.0 years. Mild liver fibrosis (F0-F1) was present in 38 patients, and significant fibrosis (F2-F4) was detected in 16 patients. Patients with significant fibrosis presented higher native T1 (954 ± 126 vs. 820 ± 123; p < 0.001) and ECV (37.9% vs. 29.1%; p < 0.001) values than those with no/mild fibrosis. Liver stiffness was correlated with native T1 (r = 0.512, p < 0.001) and ECV (r = 0.443, p < 0.001). The native liver T1 and ECV differentiated patients with and without significant liver fibrosis on MRE (AUC = 0.85 and 0.84, respectively).

Conclusion: Native T1 and ECV show potential as an alternative method for the non-invasive staging of fibrosis in patients with MASLD, although further validation in larger cohorts is needed.