RESUMO
Objective:To explore the efficacy of quantitative parameters of dual-layer spectral CT in preoperative prediction of Ki-67 expression in esophageal squamous cell carcinoma (ESCC).Methods:From December 2021 to December 2022, 64 patients with histopathologically diagnosed ESCC were retrospectively analyzed at Liaoning Cancer Hospital & Institute. The expression level of Ki-67 in ESCC tumor tissue was detected by the immunohistochemical method. The patients were divided into the Ki-67 high expression group (the Ki-67 expression index≥30%, 47 cases) and the Ki-67 low expression group (the Ki-67 expression index<30%, 17 cases). The quantitative parameters of spectral CT were measured, including traditional 120 kVp CT value, 40 keV CT value, iodine density (ID), normalized iodine density (NID), and Z-effective in arterial and venous phases. Independent sample t test was used to compare the differences in the parameters between the Ki-67 high and low expression groups. The receiver operating characteristic (ROC) curve was drawn to evaluate the efficacy of each parameter in predicting Ki-67 expression. DeLong test was used to compare the area under the curve (AUC). Results:The 120 kVp CT value, 40 keV CT value, ID, and Z-effective in the arterial phase and the 120 kVp CT value, 40 keV CT value, ID, NID, Z-effective in venous phase in the Ki-67 high expression group were all higher than those in the Ki-67 low expression group ( P<0.05). There was no statistically significant difference in arterial phase NID between the two groups ( t=1.85, P=0.070). NID in the venous phase had the highest AUC in predicting high expression of Ki-67 in ESCC (AUC=0.965, 95%CI 0.923-1.000). With a venous phase NID value of 0.28 as the diagnostic threshold, the sensitivity and specificity were 93.6% and 100%. There was no significant difference in AUC between venous phase NID and venous phase ID (AUC=0.926) and Z-effective (AUC=0.909) ( Z=-1.52, 1.81, P=0.128, 0.071), but there was a significant difference of AUC between venous phase NID and 120 kVp CT value (AUC=0.719) and 40 keV CT value (AUC=0.747) ( Z=3.41, 3.30, P=0.001, 0.001). There were statistical differences of AUC between venous phase NID and each parameter of arterial phase ( P<0.05). Conclusion:The three spectral CT parameters (ID, NID, and Z-effective) in the venous phase have high diagnostic efficacy in predicting ESCC Ki-67 expression.