Objective To investigate the diagnostic efficacy of C-TIRADS classification and SWE quantitative technique alone and in combination for diagnosis of benign and malignant thyroid nodules of different sizes. Methods There were 139 cases of thyroid nodules who underwent conventional ultrasound and SWE confirmed by pathological

the nodules were divided into group I (≤10mm) and group II (>10mm) according to the maximum diameter

and carry out C-TIRADS classification and measure the elasticity value of nodules respectively and select the index with the best stability of elasticity measurement. The ROC curve of the C-TIRADS classification、the elasticity value and the combined diagnosis of the two groups was drawn respectively，and determine the best cut-off value for benign and malignant. Compared the diagnostic efficacy of the two groups of nodules according to Z test method. Results Comparison of AUC in Group I: there was no statistical difference between C-TIRADS classification (0.866) and Emax value quantitative method (0.840) (P>0.05)

there was statistical difference between C-TIRADS classification (0.866) and combined method (0.950)、Emax value quantitative (0.840) and combined method (0.950) respectively (P＜0.05); Comparison of AUC in Group II: there was statistical difference between C-TIRADS classification (0.932) and Emax value quantitative method (0.777) 、Emax value quantitative (0.777) and combined method (0.952) respectively (P＜0.05)

there was no statistical difference between C-TIRADS classification (0.932) and combined method (0.952) (P>0.05). The research show C-TIRADS classification diagnosis a total of 5 malignant nodules of category 4A

of which 4 have Emax values greater than the best cut-off value for benign and malignant (4/5

accounting for 80%). Conclusions The combined method could improve the diagnostic efficiency of ≤10mm benign and malignant thyroid nodules ; Application of SWE technology alone to diagnosis > 10mm benign and malignant thyroid nodules was not better than the C-TIRADS classification; SWE quantitative technology method could optimization C-TIRADS 4A nodules.