ShearWave™ Elastography BE1 Multinational Breast Study: Additional SWE™ Features Support Potential to Downgrade BI-RADS®-3 Lesions

PURPOSE To determine the benefit of ShearWave™ Elastography (SWE™) in the ultrasound characterization of BI-RADS® 3 breast lesions in a diagnostic population. MATERIALS AND METHODS 303 BI-RADS® 3 lesions (mean size: 13.2 mm, SD: 7.5 mm) from the multicenter BE1 prospective study population were analyzed: 201 (66%) had cytology or core biopsy, and the remaining 102 had a minimum follow-up of one year; 8 (2.6%) were malignant. 7 SWE features were evaluated with regard to their ability to downgrade benign BI-RADS® 3 masses. The performance of each SWE feature was assessed by evaluating the number of lesions correctly reclassified and the impact on cancer rates within the new BI-RADS® 3' lesion group. RESULTS No malignancies were found with an E-color "black to dark blue", which allowed the downgrading of 110/303 benign masses (p < 0.0001), with a non-significant increase in BI-RADS® 3' malignancy rate from 2.6% to 4.1%. E-max ≤ 20 kPa (2.6 m/s) was able to downgrade 48/303 (p < 0.0001) lesions with a lower increase in BI-RADS® 3' malignancy rate (3.1%). No other SWE features were useful for reclassifying benign BI-RADS® 3 lesions. CONCLUSION Applying simple reclassification rules, SWE assessment of the maximum stiffness of lesions allowed the downgrading of a sub-group of benign BI-RADS® 3 lesions. This was accompanied by a non-significant increase in the malignancy rate in the new BI-RADS® 3 class.