Abstract: Objective: To explore the value of computed tomography (CT) enhanced long delayed scan in the CT peritoneal cancer index (CT-PCI) score of patients with peritoneal pseudomyxoma (PMP). Methods: The preoperative CT images of 102 patients with confirmed peritoneal pseudomyxoma through surgery and pathology in the Mucinous Tumor Department of Aerospace Center Hospital from October 2022 to December 2023 were retrospectively analyzed. The CT-PCI scores of the portal venous and long-delayed phases with intraoperative PCI scores were separately compared and a consistency analysis was performed. Results: The consistency between CT-PCI and intraoperative scores was evaluated using the Kappa coefficient. The Kappa values for the consistency between CT-PCI scores in 13 zones of PMP patients during CT-enhanced long-delayed scans and intraoperative PCI scores of the long-delayed phase were higher than or equal to those of the portal venous phase. The average Kappa values for the consistency between CT-PCI and intraoperative scores in 13 zones of the long-delayed and portal venous phases were 0.669±0.101 and 0.509±0.121, respectively (P < 0.001). The consistency between CT-PCI and intraoperative PCI scores was significantly higher in the long-delayed phase than that in the portal phase. The consistencies between the CT-PCI and intraoperative PCI scores in the portal venous phase are as follows: zone 1: poor consistency; zones 2, 3, 4, 5, 7, 8, 9, 10, and 12: moderate consistency; zones 0, 6, and 11: good consistency. The consistencies between the CT-PCI and intraoperative PCI scores in the long-delayed phase are as follows: zones 5, 9, 10, and 12: moderate consistency; zones 0, 1, 2, 4, 7, 8, and 11: good consistency; zones 3 and 6: very good consistency. The consistencies between the CT-PCI and intraoperative PCI scores in the portal venous and delayed phases are as follows: zones 1 and 3: significant difference; zones 0, 2, 4, 5, 6, 7, and 8: moderate difference; zones 9, 10, 11, and 12: no significant difference. Conclusion: The CT-enhanced delayed scanning method can effectively improve the accuracy of preoperative CT-PCI scoring.