Objective:To evaluate the diagnostic value of shear wave elastography(SWE) in Breast Imaging Reporting and Data System(BI-RADS) category 4A lesions. Methods:Data from 131 patients with a total of 133 breast lesions were analyzed retrospectively.Every patient underwent conventional ultrasound and SWE, and all lesions were classified as BI-RADS category 4A.Obtain the maximum shear wave velocity (SWVmax), minimum shear wave velocity (SWVmin), shear wave velocity difference (△SWV) and elastic color pattern of each lesion.Using pathological results as the gold standard, the operator's working characteristic curve(ROC) was drawn, and the area under the curve (AUC) of each method was achieved.The parameters of SWE were combined with clinical data and conventional ultrasound features to construct a logistic regression model. The diagnostic performance of this model was obtained and compared with the parameters of SWE. Results:Of 133 lesions,110 were benign and 23 were malignant.There were statistically significant difference in patient's age, the Adler stratifications of vascularity,SWVmax, SWVmin,△SWV and color pattern between benign and malignant lesions.The AUCs of SWVmax,SWVmin,△SWV and color pattern were 0.767,0.643,0.755 and 0.780,the sensitivity were 65.2%,60.9%,69.6%and 69.6%,the specificity were 90.0%,60.9%,86.4% and 86.4%,respectively.The AUCs of SWVmax,△SWV and color pattern were similar(all P>0.05),but all higher than that of SWVmin(all P<0.05).The analysis of Logistic regression showed that patient's age,the Adler stratifications of vascularity and elastic color pattern were included in the equation.The AUC,sensitivity and specificity of the model were 0.864,78.3% and 90.9%,respectively, and were higher than each parameters of SWE alone. Conclusions:SWE had a certain diagnostic value in differential diagnosis of breast BI-RADS category 4A lesions, especially SWVmax,△SWV and color pattern showed high diagnostic performance.Logistic regression analysis revealed that the combination of color pattern with patient's age and the Adler stratifications of vascularity could detection more malignant lesions and reduce the unnecessary biopsies.