The value of dual-energy CT electron cloud density and effective atomic number in differential diagnosis of benign and malignant thyroid nodules

Objective To investigate the differential diagnostic value of dual-energy CT electron cloud density （Rho） and effective atomic number （Z） between benign and malignant thyroid nodules. Methods Imaging data of 68 patients with pathologically confirmed thyroid nodules at Lingnan Hospital， the Third Affiliated Hospital of Sun Yat-sen University from March to December 2023 were retrospectively analyzed. Among the 68 cases， 31 patients were diagnosed with benign thyroid nodules and 37 with malignant thyroid nodules. All patients underwent plain CT scan combined with enhanced dual-energy CT scan of the neck in the first week before surgery. The arterial-phase and venous-phase electron cloud density maps and effective atomic number maps were reconstructed in the post-processing workstation. Rho and Z values of benign and malignant thyroid nodules were compared by Mann-Whitney U test. Statistically significant dual-energy parameters were analyzed and their differential diagnostic efficiency in diagnosing benign and malignant thyroid nodules was calculated using the receiver operating characteristic （ROC） curve. Results Arterial- and venous-phase Z values and venous-phase Rho were not statistically significant between benign and malignant thyroid nodules （all <i>P &gt; </i>0.05）， whereas arterial-phase Rho value was statistically significant between benign and malignant thyroid nodules （<i>P &lt; </i>0.05）. The arterial-phase Rho of malignant thyroid nodules was higher than that of the benign thyroid nodules， with an area under the ROC curve （AUC） of 0.711（95%CI 0.586-0.836）， a sensitivity of 73.0%， and a specificity of 64.5%. The differential diagnostic efficiency was the highest when the arterial-phase Rho was 38.6 Hu. Conclusion Dual-energy CT arterial-phase Rho mapping has certain value in the differential diagnosis of benign and malignant thyroid nodules.