Objective To investigate the application value of extracellular volume fraction(ECV)obtained from enhanced CT in diagnosis and classification of acute pancreatitis.Methods The clinical data from patients with acute pancreatitis(acute pancreatitis group)and normal controls(control group)underwent enhanced CT were analyzed retrospectively.The CT values of pancreas and abdominal aorta in the same sclice on precontrast and equilibrium-phase images were measured,and then pancreatic ECV was calcu-lated.The measured parameters were compared between the groups of control and acute pancreatitis,and subgroups of non-severe and severe pancreatitis.The logistic regression analysis was used to identify the risk factors for acute pancreatitis and severe pancrea-titis,and the receiver operating characteristic(ROC)curve was used to analyze the diagnostic efficiency in diagnosis and classifica-tion of acute pancreatitis.Results The pancreatic CT value and ECV were independent risk factors for acute pancreatitis(P＜0.05),and the ECV was an independent risk factor for severe pancreatitis(P＜0.05).The area under the curve(AUC)of ECV was higher in acute pancreatitis group(0.81)and severe pancreatitis subgroup(0.68).Conclusion As a quantitative parameter,the ECV obtained from enhanced CT has higher clinical application value and higher popularity in the diagnosis and classification of acute pancreatitis.