What is the Origin of Hepatic Fat Fraction?

The gold standard for measuring liver fat has historically relied on an invasive liver biopsy, but the development of advanced magnetic resonance imaging (MRI) techniques, particularly the proton density fat fraction (PDFF) method, established HFF as a reliable, quantitative, and non-invasive alternative. The clinical adoption of HFF reflects a major technological evolution in diagnostic imaging, moving away from subjective qualitative assessments. This objective metric has become central to the clinical assessment of metabolic and endocrinological health.

What is the Mechanism of Hepatic Fat Fraction?

The mechanism for accurately determining HFF, typically achieved via MRI-PDFF, relies on the distinctly different magnetic properties of water protons versus fat protons within the liver tissue. The specialized imaging sequence acquires data that allows for the precise mathematical separation and quantification of the signal originating from water versus the signal originating from fat. This robust process provides an objective percentage of fat content, offering a far more reproducible and sensitive measure of steatosis severity than older, less quantitative imaging methods.

Hepatic Fat Fraction

Meaning

Hepatic Fat Fraction (HFF) is a quantitative, non-invasive imaging metric that precisely represents the proportion of fat, specifically stored triglycerides, within the liver parenchyma relative to the total liver volume. Clinically, HFF is considered a critical and objective biomarker for the accurate diagnosis and ongoing monitoring of hepatic steatosis, commonly known as fatty liver disease. An elevated HFF is strongly correlated with underlying metabolic dysfunction, significant insulin resistance, and an increased risk of progression to more severe non-alcoholic steatohepatitis (NASH).