MRI-Derived Muscle Composition and Visceral Adiposity in Relation to Mortality and Vascular Outcomes in MASLD

Background/Objectives: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a cardiometabolic phenotype rather than a single-pathway liver disorder, yet prognostic work tends to privilege liver fat over the rest of body composition. We examined which magnetic resonance imaging (MRI)-derived compartment, including hepatic, abdominal adipose, or skeletal muscle, best explained risk within MASLD.

Methods

We investigated 24,976 UK Biobank adults with abdominal MRI, including 10,490 with MASLD, 2577 with MASLD with increased alcohol intake, and 11,909 without steatotic liver disease. Five MRI parameters were examined: proton density fat fraction (PDFF), visceral adipose tissue (VAT), abdominal subcutaneous adipose tissue (ASAT), muscle fat infiltration (MFI), and thigh fat-free muscle volume (FFMV). Primary outcomes were all-cause mortality, incident cardiovascular disease, and incident cerebrovascular disease. Cox models jointly included all five MRI variables and adjusted for demographic, metabolic, and biochemical covariates.