Abstract： Objective:To investigate CT imaging appearance of pancreatic solid pseudopapillary neoplasm (pSPN) in predicting pathological invasive behaviors.Methods:The clinical data and CT data of 103 patients with solid pseudopapillary neoplasm confirmed by surgical resection and pathology were retrospectively analyzed. According to the pathological results, all cases were divided into two groups: invasive group with 38 cases and non-invasive group with 65 cases. All 103 cases of pSPN had a single lesion. Image analysis included tumor location, size, shape, capsule,calcification, hemorrhage and proportion of cystic or solid component, etc. The density of solid components in all lesions was measured in plain scan, arterial phase and venous phase of CT images. Enhancement degree in arterial phase, enhancement degree in venous phase and enhancement degree between venous phase and arterial phase were calculated, and the differences between the two groups were statistically analyzed. For data analysis, the comparison of continuous variables between two groups was done with Student′s t-test. Categorical variables were tested using the χ 2 test or Fisher′s exact test. Diagnostic accuracy of density in arterial phase, density in venous phase, enhancement degree in arterial phase and enhancement degree in venous phase were assessed as the area under the receiver-operating characteristic (ROC) curve. Results:There were statistically significant differences in tumor capsule and proportion of cystic or solid component between the two groups ( P<0.05). There were no significant differences in neoplasm maximum diameter, location, morphology, calcification, hemorrhage, pancreaticobiliary dilatation and pancreatic atrophy between the two groups ( P>0.05). The density[(76.65±16.71) HU] and enhancement degree[(41.04±17.02) HU] in venous phase in invasive group were higher than those in non-invasive group [respectively (70.09±12.02),(34.55±11.41) HU] and the differences were statistically significant ( P<0.05). There were no statistically significant differences in the density in plain scan, density in arterial phase, enhancement degree in arterial phase and enhancement degree between venous phase and arterial phase ( P>0.05). The area under the ROC curve of density in arterial phase, density in venous phase, enhancement degree in arterial phase and enhancement degree in venous phase were respectively 0.598, 0.634, 0.613, and 0.617, among which only density in venous phase had the discriminant efficacy, and the optimal critical value was 78.65 HU. Conclusion:The pSPN has no capsule or incomplete capsule, more solid components, and obvious enhancement of the solid components in the tumor in venous phase may suggest that the tumor has more invasive behavior.