ObjectiveTo evaluate the value of spectral CT monoenergetic imaging in optimizing the image quality of peripancreatic great vessels in patients with pancreatic malignant tumors. MethodsThe imaging data of 62 patients with pancreatic malignant tumors who underwent contrast-enhanced spectral CT at West China Hospital of Sichuan University from July 2018 to March 2021 were retrospectively analyzed. A total of 21 monoenergetic image sets (from 40 to 140 keV at 5 keV intervals) were reconstructed. The CT value, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of the peripancreatic great vessels (including the celiac artery, common hepatic artery, superior mesenteric artery, portal vein, and superior mesenteric vein), as well as the tumor-to-parenchyma ratio (TPR) in the pancreatic parenchymal and portal venous phases, were compared between the mixed-energy images and the monoenergetic images. Additionally, subjective evaluations of vascular involvement in both the mixed-energy and optimal monoenergetic images were performed. ResultsThe overall differences in CT values, SNR, and CNR of the peripancreatic great vessels among mixed-energy and 21 monoenergetic image sets were all statistically significant (all P<0.001). In the monoenergetic images, as the energy level increased, the CT values, SNR, and CNR of the five peripancreatic great vessels showed consistent decreasing trends (all P<0.001). The 40 keV group exhibited the highest values for all indexes, indicating the best visualization. Regarding the TPR, both the pancreatic parenchymal and the portal venous phases showed a decrease as the energy level increased. The intergroup difference in TPR in the pancreatic parenchymal phase was statistically significant (P<0.001), while no significant difference was observed in the portal venous phase (P>0.05). The 40 keV monoenergetic images achieved the highest TPR, providing optimal lesion visualization. The subjective evaluations by two physicians on vascular involvement in 40 keV monoenergetic images and mixed-energy images showed good to excellent interobserver agreement (Kappa=0.775–1.000, all P<0.001). ConclusionThe 40 keV image from spectral CT can significantly optimize the imaging of peripancreatic great vessels, providing better subjective and objective image quality.