Effect Of Lesion Size On Shear Wave Elastography In Diagnosing Solid Breast Nodules With Category 4 Of BI-RADS

Purpose: The technology of shear wave elastography was applied to diagnosing the benign and malignant breast nodules with category 4 of BI-RADS,and explore whether the diagnostic performance of SWE is affected by the size of nodules.Methods: A total of 181 patients with solid breast nodules admitted to the First Affiliated Hospital of Anhui Medical University from February 2021 to May 2022 were collected.The ultrasound BI-RADS classification results were all classified into 4 categories.Images were performed by using the France Supersonic Aixplorer ultrasonic apparatus,equipped with linear array probe.The ultrasonic characteristics and SWE parameters were recorded,including the maximum elastic modulus(Emax),and mean elastic modulus(Emean)values.According to the maximum diameter measured by ultrasound,there were categorized into three subgroups: large group(≥20mm),middle group(10-20mm)and small group(≤10mm).The correlation between lesion size and elastic parameters were analyzed.The differences between Emax and Emean values were compared among groups.The receiver operating characteristic curves(ROC)were plotted using pathological results as the gold standard to calculate the optimal threshold of Emax and Emean in each group.The differences of area under the curve(AUC),sensitivity and specificity were compared between the total threshold and the optimum threshold of elastic parameters in the three groups.Results:1.The hardness of malignant breast nodule was significantly higher than benign in all groups,and the difference was statistically significant(P = 0.000).2.The correlation of Emax and Emean with the maximum diameter of breast nodule were0.566 and 0.495,respectively(P = 0.000、P = 0.000),and the correlation with the average size were 0.619 and 0.533,respectively(P = 0.000、P = 0.000).The correlation between SWE quantitative parameters and the average nodule size was better than the maximum diameter,and the correlation between Emax and nodule size was higher than Emean.3.The median values of Emax and Emean parameters in the three groups of large,medium and small nodules were 185.20 kPa,101.00 kPa,36.10 kPa and 55.00 kPa,35.00 kPa,17.20 kPa,respectively.With the increasing of nodule size,the stiffness has an increasing trend.Pair comparison among the three groups showed significant differences in Emax values(P = 0.000,P = 0.000,P = 0.000),and statistically significant differences in Emean values(P = 0.000,P = 0.000,P = 0.004).4.In the total,large,middle and small groups,the optimal diagnostic thresholds of Emax and Emean were 107.70 kPa,122.90 kPa,108.20 kPa,67.00 kPa and 32.10 kPa,48.50 kPa,31.00 kPa,16.30 kPa,respectively.In the large and small nodules groups,the AUC value of using optimal threshold of Emax was higher than the total threshold(0.948 vs0.934,0.864 vs 0.710).It has a statistically significant difference in small group(P =0.0158).The AUC value of using optimal threshold of Emean was also higher than the total threshold(0.892 vs 0.731 and 0.798 vs 0.586).And the differences between the two groups were both statistically significant(P = 0.038,P = 0.002).5.In the large nodule group,the specificity of Emax in the diagnosis of benign and malignant breast increased from 90.00% to 100.00%,and that of Emean increased from54.50% to 90.90%.In the small nodule group,the sensitivity of Emax was improved from46.70% to 80.00%,and that of Emean was improved from 26.70% to 100.00%.6.In the large,middle and small and total groups,the AUC value of Emax in the diagnosis of benign and malignant breast was higher than that of Emean,but it has no statistical significance(P < 0.05).The diagnostic specificity of Emax was higher than that of Emean parameters in all groups.Conclusions: The values of Emax and Emean,which were the most widely used parameters of SWE,were moderate positively correlated with the size of breast nodule.For maximum diameter ≥20mm and ≤10mm solid breast nodules with category 4 of BI-RADS,adjustment of the threshold of elastic parameters was beneficial to improve the diagnostic efficiency of quantitative parameters of SWE.