Ultrasound-derived Fat Fraction for Pre-operative Prediction and Monitoring of Hepatic Steatosis Normalization After...

To validate ultrasound-derived fat fraction (UDFF) against histology for diagnosing hepatic steatosis, monitor metabolic changes after metabolic and bariatric surgery, and develop a pre-operative nomogram for predicting early steatosis normalization.

A prospective cohort of 160 patients scheduled for metabolic and bariatric surgery was enrolled. Among them, 120 patients with biopsy-confirmed metabolic dysfunction-associated steatotic liver disease (hepatic fat ≥5%) underwent repeated assessments of UDFF, anthropometrics, and biochemical markers pre-operatively and at 30, 90, and ≥180 days post-operatively. Follow-up completion rates were 82.5%(99/120) at 30 days, 76.7% (92/120) at 90 days, and 60.0%(72/120) at ≥180 days. Using data from 92 patients with complete 90-day follow-up, a nomogram was developed via uni-variable and multi-variable logistic regression. Its performance was evaluated by the area under the curve (AUC), calibration, and decision curve analysis.

UDFF demonstrated a strong correlation with histological steatosis grade (Spearman's ρ=0.78;p<0.001) and high diagnostic accuracy for ≥S1 steatosis (AUC=0.99). Post-operative monitoring revealed rapid, phased reductions in UDFF, body weight, and triglyceride levels. Baseline weight, UDFF, and triglycerides were identified as independent predictors of steatosis normalization (all p<0.05). The nomogram integrating these predictors exhibited good discrimination (AUC=0.84), calibration, and clinical utility.

UDFF is a valid, non-invasive tool for quantifying hepatic steatosis and monitoring treatment response. The developed nomogram provides a practical means for the pre-operative identification of patients at risk for delayed normalization, thereby facilitating personalized surgical management and optimizing follow-up strategies.