Diagnostic performances of shear-wave elastography and B-mode ultrasound to differentiate benign and malignant breast lesions: the emphasis on the cutoff value of qualitative and quantitative parameters.

Purpose: To investigate the most effective cutoff values for shear-wave elastography (SWE) for differentiating benign and malignant breast lesions and to evaluate the diagnostic performance of quantitative and qualitative SWE in combination with B-mode ultrasound (US).

Methods: 209 breast lesions from 200 patients were evaluated with B-mode US and SWE. Pathologic results determined by US-guided core needle biopsy or surgical excisions were used as a reference standard. Qualitative (four-color pattern) and quantitative analyses (Emean, Emax, SD, and E ratio) were performed. The cut-off values were defined using Youden's index. The diagnostic performance of B-mode US and combination of B-mode US with four-color pattern or quantitative parameters were compared.

Results: Of the 209 breast lesions, 102 were benign and 107 were malignant. All qualitative and quantitative SWE parameters had significantly higher specificity, positive predictive value (PPV), and accuracy compared to B-mode US (p < 0.001). The optimal cutoff values for the Emax, Emean, SD and E ratio were 145.7 kPa, 89.1 kPa, 11.9, and 3.84, respectively. The optimal cutoff for color pattern was between 3 and 4. Combined B-mode US and Emax had the highest improvement, from 17.65% to 98.04% for specificity and from 58.85% to 82.78% for accuracy, with a decrease in sensitivity compared with B-mode.

Conclusion: Quantitative and qualitative SWE combined with B-mode US improved the accuracy to differentiate benign from malignant lesions. Emax (cutoff, 145.7 kPa) appeared to be the most discriminatory parameter.