Diagnostic accuracy of shear wave elastography – Virtual touch™ imaging quantification in the evaluation of breast masses: Impact on ultrasonography’s specificity and its ultimate clinical benefit

Abstract

ObjectivesTo evaluate the diagnostic performance and the clinical benefit of Shear-Wave Elastography - Virtual Touch™ Imaging Quantification (SWE-VTIQ) as a complement to ultrasonography (US). MethodsFrom October 2016 through Jun 2017, B-mode US and SWE-VTIQ were prospectively performed in 396 breast masses in 357 women who consented to undergo this study. Quantitative elastography values were recorded: Vmax (maximum elasticity), Vmean (median elasticity), Vratio(max) (ratio of Vmax and surrounding parenchyma) and Vratio(mean) (ratio of Vmean and surrounding parenchyma). The histopathology of the lesions was considered the reference standard for benign or malignant definition. The performance of the four elastographic parameters was evaluated trough sensitivity, specificity and AUC. The parameter with the best performance was tested in six different diagnostic approaches defined based on clinical practice. ResultsOf the 396 masses, 122 (30.8%) were benign and 274 (69.2%) were malignant. All SWE parameters were significantly higher in malignant masses (all p < 0.01). Vmax and Vratio(max) performed significantly better then Vratio(mean) (p = 0.01 and p = 0.03, respectively). SWE-VTIQ improved US specificity in all diagnostic approaches, except when applied to BI-RADS 3 lesions. SWE-VTIQ reduced the false positive rate in 25% if applied only to BI-RADS 4A masses, maintaining a high sensitivity (98.9%, 95% confidence interval 97.1–100%) and a negative predictive value of 95.5%. When applied to BI-RADS 4A and 4B masses, SWE-VTIQ reduced the false positive rate in 54.4%. However, 13 malignant cases would be missed in this approach (4.7% of all malignant cases). ConclusionsSWE-VTIQ increases US specificity when applied to BI-RADS 4 A lesions, significantly reducing unnecessary interventions and preserving the diagnosis of malignant lesions. When applied also to BI-RADS® 4B lesions, SWE-VTIQ increases the number of false negative cases, which should be evaluated with caution.