Objective To assess the value of elastosonography for the diagnosis of thyroid microcarcinoma (TMC),especially with regard to elastic score (ES) and strain ratio (SR).Materials and methods Conventional ultrasound and elastography were performed for 487 thyroid micronodules before surgery.Using histology as a reference standard,the ES and SR values as well as their diagnostic threshold and efficiency were compared and analyzed by the receiver-operating characteristic (ROC) curve between the TMC and benign groups.Additional comparisons between TMC patients with and without extracapsular extension were also performed.Results 375 nodules were found to be TMC and 112 nodules were identified as benign.There were statistically significant differences (P < 0.05) in both ES and SR values between the TMC and benign groups.The area under the ROC curve (AUC) of SR was significantly greater than that of ES (0.844 and 0.956,respectively; P < 0.05).Using ES ≥ 3 and SR ≥ 3.65 values as a diagnostic threshold,the diagnostic sensitivity,specificity,and accuracy of ES and SR for differentiating benign and malignant nodules was 79.9%,72.3%,80.5%,and 86.6%,85.3%,89.4%,respectively.The maximum diameter,microcalcification status,aspect ratio,bilateral cervical lymph node metastasis,and SR values of nodules with extracapsular extension (A1 subgroup) were all greater than those of nodules without extracapsular extension (A2 subgroup).Conclusions Elasticity imaging technology can not only help to differentiate between benign and malignant thyroid micronodules,but SR values can also provide more accurate and objective information on the tissue hardness,and to some extent,can predict TMC extracapsular extension or even bilateral cervical lymph node metastasis.