Background: ShearWaveTM Elastography (SWE) is a real time ultrasound imaging technique that quantitatively measures local tissue elasticity in kPa. This new information is adding to tissue characterization and complements gray scale imaging. The reproducibility of the technique was evaluated on breast lesions. Finally, the pertinence of the new information for breast lesions assessment was analyzed retrospectively on subsets of data collected from three clinical sites.
Material & Methods: 183 solid breast lesions from 24 to 85 year old patients were evaluated. The reproducibility of SWE was analyzed by a measure of the variance of consecutive elasticity images acquired under the same clinical conditions. For subsets of lesions in each BI-RADS® category 3, 4 and 5, SWE information was compared to the ground truth: biopsy results for BI-RADS® 4 and 5, biopsy or follow up for BI-RADS® 3.
Results: SWE detected all lesions with a spatial resolution of 1 mm and measurement of tissue elasticity was achieved in all cases in a reproducible way. The technique brought new clinical information that augmented lesion characterization. Furthermore, the mean elasticity of malignant lesions was significantly higher than the mean elasticity of benign lesions (153 kPa [SD, 51.6 kPa] vs. 54 kPa [SD, 31 kPa]).
Conclusions: SWE, as implemented in the Aixplorer™ system, provided reproducible quantitative elasticity measurements, which complemented B-mode diagnosis information in the 183 breast lesions. On known cysts, SWE systematically showed an absence of signal, which might have an interest in cysts characterization.