MRI-based biomarkers for risk stratification and assessment of treatment response in Metabolic dysfunction-associated Steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) affects up to 38% of the population globally. Liver biopsy, the historical reference standard, is invasive, subject to sampling error and not scalable. MRI-based biomarkers provide non-invasive, quantitative whole liver assessment. MRI proton density fat fraction (MRI-PDFF) is the most accurate noninvasive measure of steatosis (thresholds of 6.4%, 17.4% and 22.1% for grades ≥1, ≥2 and 3), and a ≥30% relative reduction is associated with histologic response. Liver stiffness by magnetic resonance elastography (MRE-LS) is the most accurate imaging biomarker for fibrosis: MRE-LS of 3.1-4.4 kPa corresponds to F2-F3 and ≥5 kPa to cirrhosis, and each 1-kPa increase is associated with a 43% higher risk of hepatic decompensation. Iron-corrected T1 is a sensitive but nonspecific marker of disease activity whose prognostic value requires further study. Composite scores, MAST, MEFIB, and MASH Resolution Index, combine imaging and blood tests for advanced fibrosis diagnosis and response assessment. MRE is cost-effective compared with vibration-controlled transient elastography for detecting advanced fibrosis. Artificial intelligence may broaden access by automating analysis and enabling PDFF from routine MRI. We review the evidence supporting these biomarkers for diagnosis, prognosis and regulatory use, and their role in clinical trials and in treatment decisions for approved MASH therapies.