Ultrasound-derived Fat Fraction for Pre-operative Prediction and Monitoring of Hepatic Steatosis Normalization After Metabolic Surgery in Patients With Obesity

OBJECTIVE: 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. METHODS: 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. RESULTS: UDFF demonstrated a strong correlation with histological steatosis grade (Spearman's ρ=0.78;p