Metabolic Dysfunction-Associated Fatty Liver Disease Impairs Intraoperative Indocyanine Green Fluorescence Cholangiography Quality: Development and Validation of a Predictive Model

The common bile duct-to-liver background fluorescence intensity ratio (C/L) [Unit: Dimensionless number] [Time Frame: Perioperative period] [Measurement steps: Three photographs per case were obtained with the following requirements: Calot's triangle centred in the image, liver background positioned superiorly, and the CBD inferiorly, ensuring all measurement sites were visible and unobstructed. Each image was converted to greyscale, and regions of interest (ROI) of >3000 pixels were selected for each critical structure to calculate FI. The mean FI from the three images was recorded as the final value for each structure.]

Qualitative assessment of fluorescence visualization. [Time Frame: Perioperative period] [Unit: Dimensionless number] [Measurement steps: It was performed by three senior surgeonsScores were averaged and graded on a five-point scale adapted from previous studies (1=completely invisible, impairs visualization; 2=poor, faint fluorescence, no added value; 3= visible but blurred, some added value; 4=good, clear visualization with significant added value; 5= excellent, very clear visualization with typical added value)]

HSI（Hepatic Steatosis Index) and FSI (Framingham Steatosis Index) [Time Frame: Perioperative period] [Unit: Dimensionless number] [The variables included：ALT and AST(IU/L), BMI(kg/m2), gender(male/female), diabete(yes/no), age(years), TG (mmol/L), Hypertension(yes/no)]