Objectives <p>To investigate the value of spectral CT-derived extracellular volume fraction (fECV) in assessing liver functional reserve and predicting cirrhosis-related complications in clinically stable cirrhotic patients.</p> Materials and methods <p>This retrospective study enrolled clinically stable patients with cirrhosis who underwent contrast-enhanced spectral CT examinations, as well as a control group without major diseases. Iodine concentrations in the liver and aorta were measured on equilibrium phase images to calculate the fECV. The diagnostic performance of fECV for Child-Pugh classification was evaluated using receiver operating characteristic (ROC) curve analysis. The predictive ability of fECV for cirrhosis-related complications was assessed using the Kaplan-Meier time-dependent ROC curves, and Cox proportional hazards regression models.</p> Results <p>A total of 116 patients with cirrhosis (mean age, 60.20 ± 12.11 years) and 38 control subjects (mean age, 60.16 ± 8.93 years) were enrolled in this study. The area under the ROC curve (AUC) of fECV for differentiating Child-Pugh classes was 0.852-0.881 (all p &lt; 0.001). The high fECV group (≥38.48%) demonstrated a significantly higher cumulative risk of complications (p &lt; 0.001). fECV showed superior predictive performance for long-term (3-year) complications (AUC = 0.813, p &lt; 0.001). Furthermore, fECV was identified as an independent risk factor for cirrhosis-related complications (Model 1: HR = 1.073, p = 0.004; Model 2: HR = 1.078, p &lt; 0.001).</p> Conclusion <p>fECV is a promising imaging biomarker for liver functional reserve assessment and complication prediction in cirrhosis.</p>