To assess the application value of quantitative and qualitative parameters of shear wave elastography (SWE) in evaluting Ki-67 expression levels in breast cancer.

A total of 82 lesions in 80 patients diagnosed pathologically with breast cancer were collected from March 2019 to January 2020 at the First Affiliated Hospital of Soochow University. The maximum diameter and elastic modulus of breast lesions and the 1-mm and 2-mm marginal zones around the lesions were quantitatively measured by gray-scale ultrasound and SWE. The stiff rim sign was observed by SWE imaging. Using the immunohistochemical analysis after surgery or puncture biopsy as the gold standard, ROC curve analysis was performed to obtain the optimal qualitative and quantitative indicators to predict the level of Ki-67 expression in breast cancer and to assess the efficiency of the combination of the optimal quantitative parameters and qualitative indicator for Ki-67 index grading.

Among the 82 lesions, 33 had low Ki-67 expression and 49 had high expression. The area under the ROC curve (AUC) of the maximum diameter (≥2 cm) measured by gray-scale ultrasound was 0.741, with a sensitivity of 63.3% and specificity of 84.8%. The AUC of stiff rim sign was 0.837, and the sensitivity and specificity were 79.6% and 87.9%, respectively. The maximum value of elastic modulus in the 2-mm marginal zones around the lesions (E2Smax) in the high-expression group was significantly higher than that in the low-expression group (P＜0.001); it had the highest AUC value (0.719) among the SWE quantitative indexes (cut-off value, 95.86kPa; sensitivity, 69.4%; specificity, 72.7%). The AUC of the combination of the stiff rim sign and the maximum diameter was 0.889, with a sensitivity of 91.8% and specificity of 78.8%. The AUC of the combination of E2Smax and the maximum diameter was 0.808, with a sensitivity of 83.7% and specificity of 69.7%.

The quantitative parameters and qualitative indexes of gray-scale ultrasound and SWE of breast cancer lesions and the marginal zones around the lesions have good application value in evaluating Ki-67 expression, among which the maximum diameter, the stiff rim sign, and E2Smax have higher diagnostic efficiency, especially the combination of the stiff rim sign and the maximum diameter, which can provide an objective and reliable basis for early diagnosis of tumor invasiveness and prognosis evaluation after treatment.