Abstract:Objective To analyze the ultrasonographic features and diagnostic efficacy of color Doppler ultrasonography (CDU) of malignant thyroid nodules， to provide reference for clinical diagnosis and differential diagnosis. Methods The clinical data of 110 patients with thyroid nodules treated in Shaanxi Provincial Hospital of Chinese Medicine from January 2020 to January 2022 were retrospectively collected, and were divided into the benign group and the malignant group according to the pathological examination. The ultrasonic features, blood flow classification and blood flow parameters of the two groups were compared. Results Among the 110 patients with thyroid nodules, 26 were malignant and 84 were benign. The sensitivity, specificity and accuracy of CDU in the diagnosis of malignant thyroid nodules were 88.46%, 95.24% and 93.64%, respectively. The proportion of patients with irregular morphology (76.92% vs 10.71%, χ2=44.833), low echo, aspect ratio ≥1 (69.23% vs 10.71%, χ2=36.708), blood flow types Ⅲ and Ⅳ were higher than those in the benign group (P＜0.05). Peak systolic blood flow velocity (PSV) and resistance index (RI) in the malignant group were higher than those in the benign group, and end diastolic velocity (EDV) was lower than that in the benign group (P＜0.05). Conclusion CDU examination has good diagnostic efficacy in the differentiation of benign and malignant thyroid nodules. Irregular morphology, low echo, and aspect ratio ≥ 1 are the ultrasound features of malignant thyroid nodules. The main blood flow types are Ⅲ and Ⅳ, with higher RI and PSV.