Application of dual-energy computed tomography in preoperative evaluation of Ki-67 expression levels in solid non-small cell lung cancer

To investigate whether there were significant differences in dual-energy CT (DECT) in reflecting different quantitative parameters among different levels of Ki-67 expression in patients with solid non-small cell lung cancer (NSCLC). The diagnosis performance of DECT in patients with solid lung adenocarcinoma (LAC) among NSCLC was further discusses. Two hundred fifteen patients confirmed with solid NSCLC were enrolled and analyzed retrospectively in this study. 148 patients were confirmed with LAC among all patients. Three expression levels of Ki-67 were determined by the percentage of Ki-67 positive cancer cells with immunohistochemistry: high-level group (>30%), middle-level group (10%-30%), and low-level group (≤10%). And the latter two levels also known as non-high-level group. The quantitative parameters of enhanced chest DECT (venous phase, VP), including iodine concentration (IC), water concentration (WC), CT value at 40 keV (CT40keV), the slope of energy spectral attenuation curve (λHU) and normalized iodine concentration (NIC) were measured and calculated by gemstone spectral imaging Viewer software. One-way ANOVA was used for the comparison of normal distribution DECT parameters between three levels for patients with NSCLC and patients with LAC. Non-normal distribution data were tested by non-parametric test. In addition, the receiver operating characteristic curve of statistically significant DECT parameters was drawn to distinguish the non-high-level and the high-level of Ki-67. Area under the curve (AUC), sensitivity, specificity was calculated to measure the diagnostic performance of parameter. Both in solid NSCLC and LAC, the IC, NIC, WC, λHU and CT40keV at VP in the high-level group were significantly lower than those in the middle- and low-level group respectively, and the WC at VP in the high-level group was significantly higher than that in the middle- and low-level group respectively (all P < .05). Receiver operating characteristic analysis showed that IC and λHU at VP performed better in distinguishing the high-level and the non-high-level of Ki-67 (NSCLC: AUC = 0.713 and 0.714 respectively; LAC: AUC = 0.705 and 0.706 respectively). Quantitative parameters of DECT provide a new non-invasive method for evaluating the proliferation of cancer cells in solid NSCLC and LAC.