Abstract: Objective To evaluate the value of double-phase enhancement CT scan in the differential diagnosis of benign and malignant thyroid nodules. Methods The CT data of 182 nodules confirmed by histology in 175 patients were retrospectively analyzed, including 60 benign nodules and 122 malignant nodules. The shape, density, location, CT difference between thyroid and nodules(ΔCT)and reinforcement type were evaluated between the benign and malignant groups. Univariate and multivariate dichotomous Logistic regression were performed to evaluate the OR value of CT features of benign and malignant nodules, and the area under the receiver operating characteristic(ROC)curve were compared between the two groups. Results There were significant differences in the shape(χ2=50.661, P<0.001), density(χ2=60.042, P<0.001), location(χ2=48.916, P<0.001)and ΔCT value(χ2=45.647, P<0.001)between benign and malignant nodules, but there was no significant difference in reinforcement type(χ2=1.586, P=0.434). The area under the ROC curve was 0.899 for the combined prediction probability of four positive signs. When the prediction probability was 0.711, the Youden Index reached its maximum value, and the sensitivity and specificity of diagnosing malignant nodules were 0.869 and 0.783, respectively. Conclusion CT double-phase enhanced scan is of great value in the differential diagnosis of benign and malignant thyroid nodules. Combination of multiple CT signs can improve the accuracy of diagnosis.

Key words: Thyroid neoplasms, Goiter, Nodular, Tomography, Spiral computed