Abstract： Aim To explore the predictive value of energy CT normalized iodine concentration(NIC)for lymph node metas-tasis in rectal cancer.Methods The clinical data of 42 rectal cancer patients were prospectively analyzed and divided into lymph node metastasis-positive and negative groups according to the pathological results of the largest lymph node in the postoperative region,and the short diameter of the largest lymph node and the NIC were measured by using a post-processing station.The lymph node short diameters and NIC values were compared between the two groups.Single-factor and multifactorial Logistic regression analyses were used to predict the influencing factors of lymph node metastasis.ROC analysis was performed to analyze the predictive value of lymph node short diameter and NIC for lymph node metastasis in rectal cancer.Results There were significant differences in lymph node T staging,arterial phase NIC,and short diameter between the two groups(P＜0.05).The NIC and short diameter during the arterial phase of lymph nodes were influencing factors for lymph node metastasis in rectal cancer.ROC results showed that the diagnostic effi-cacy of arterial phase NIC was similar to that of lymph node short diameter,while the diagnostic efficacy of combined diagnosis was sig-nificantly greater than that of individual indicators.Conclusion The NIC of energy CT has certain predictive value for regional lymph node metastasis in rectal cancer.