Objective: To determine whether shear wave elastography [SWE] can increase specificity in diagnosis of benign and malignant breast masses in BI-RADS category 3 and 4.

Materials and Methods: Data were collected retrospectively between January 2013 and December 2015 at King Chulalongkorn Memorial Hospital. Breast sonography with supplementary SWE of BI-RADS category 3 and 4, according to the ACR BI-RADS 2013, which had histopathology-proved diagnosis or at least two years of stability, were randomly reviewed by the researchers. Elasticity values were all generated by Supersonic Imagine ultrasound system. Minimal elasticity [Emin], mean elasticity [Emean], and maximal elasticity [Emax] values were separately evaluated among benign and malignant groups.

Results: One hundred sixteen lesions in 107 female patients were eligible for the present study. Eighty lesions (68.9%) were benign and 36 lesions (31.0%) were malignant. All Emin, Emean, and Emax showed statistically significant difference between benign and malignant lesions (p-value 0.022, 0.001, and <0.001, respectively). The area under the receiver operating curve [AUC] for elasticity value was slightly higher for maximum (0.733) than mean (0.710) values. The cut-off value of Emax was 110 kPa, showing sensitivity 63.9%, specificity 78.8%, PPV 57.5%, NPV 82.9%, and accuracy 74.1%. All BI-RADS category 3 lesions were benign, as well as all BI-RADS category 4c lesions, were malignant. The cut-off value of Emax below 48 kPa in BI-RADS category 4a lesions proved to be all benign except medullary carcinoma. Maximal Emax value was 300 kPa, which was proven to be diabetes mellitus mastopathy and some malignant lesions.

Conclusion: Emin, Emean, and Emax values were significantly different between benign and malignant masses and the specificity was increased as compared with conventional ultrasound alone, especially in BI-RADS category 4a. The present study showed Emax value at 110 kPa had good specificity and high NPV. Elasticity values primarily reflect the degree of fibrosis of breast lesions, which help the diagnosis.

Keywords: Shear wave elastography, Diagnostic accuracy, Benign, Malignant, Breast masses, BI-RADS 3 and 4