Ultrasonographic fatty liver indicator (US-FLI): a reliable biomarker for non-invasive NAFLD stratification

Here, we comment on a recent article supporting the use of the ultrasonographic fatty liver indicator (US-FLI) as a point-of-care biomarker to be used in the community to rule out nonalcoholic steatohepatitis (NASH). To this end, we discuss definitions and characteristics of US-FLI, and we critically summarize the principal studies published from 2012 to 2023. We conclude that US-FLI exhibits high reproducibility. It finds utility across both the pediatric population and the point-of-care settings. Furthermore, it demonstrates a robust correlation with metabolic derangements, and also serves as a predictive tool for varying grades of hepatic steatosis and important liver histology endpoints. Notably, it excels in its capacity to differentiate between bland steatosis and true NASH. However, US-FLI reportedly exhibits limited accuracy among patient populations with obesity. Finally, we propose a detailed agenda to advance research on US-FLI.