The Role of Shear Wave Elastography in Differentiating Idiopathic Granulomatous Mastitis From Breast Cancer

Abstract

Shear wave elastography (SWE) uses focused radiation forces without manual compression and is intrinsically not operator dependent. Shear waves travel faster in stiffer tissue and slower in softer tissues. The purpose of this study was to determine the role of SWE, imaging, and point measurements in differentiating idiopathic granulomatous mastitis (IGM) from breast cancer. Data from 168 patients diagnosed with breast cancer (n= 80) or IGM (n = 88) through image-guided biopsy were included in the study. All patients were evaluated with SWE followed by conventional ultrasonography (US). Shear wave velocity (Vs) and the SWE scoring system (Tsukuba) were used to evaluate lesions, which were classified synchronously according to the Breast Imaging Reporting and Data System (BI-RADS) by using conventional US. Lesion size and BI-RADS scores were recorded, and the scores of the lesions were compared between the two groups. The diagnostic capacity of the Vs value was measured by the area under the receiver operating characteristic curve (AUC, 0.94). The mean age was 37 ± 9 years for patients with IGM and 49 ± 13 years for patients with breast cancer. Both Breast Imaging Report and Data System (BI-RADS) and SWE scores were significantly higher in breast cancer patients than in IGM patients (p < 0.01). However, unlike the Vs values and SWE scores, the BI-RADS scores were not low enough in many IGM cases to avoid biopsy. The mean Vs value of IGM lesions was 2.5 ± 1.17 m/s, which was significantly lower than that of breast cancer (5.2 ± 0.76 m/s, p < 0.01). The cut-off value was 4.1 m/s, and the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 97.5%, 93%, 92.6%, 97.6%, and 95.2%, respectively (p < 0.01). SWE has high sensitivity and specificity in differentiating IGM from breast cancer with a lower SWE score and Vs value. Implementing this approach in clinical practice could reduce the number of unnecessary biopsies.