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. ResultsThere were significant differences in the CT values, SNR, and CNR of peripancreatic vessels between the mixed energy images and the 40–140 keV groups (all P<0.001). The 40 keV group showed higher CT values, SNR, and CNR than both the mixed energy images and the 75–140 keV groups (all P<0.001). The performance was more prominent when using 40 keV images. The subjective evaluation agreement between the two radiologists was good to excellent, with Kappa values ranging from 0.704 to 1.000 (all P<0.001). ConclusionThe 40 keV images from spectral CT can significantly optimize the imaging of peripancreatic great vessels, providing better subjective and objective image quality.