Significant Differentiation of Focal Breast Lesions: Raw Data-Based Calculation of Strain Ratio

Abstract

We compared elastography, B-mode ultrasound and mammography to determine whether raw data calculation of strain ratios (SRs) can further improve the differentiation of focal breast lesions. 201 women with histologically proven focal breast lesions (85 benign, 116 malignant) were included at two German breast centers. Patients underwent a standardized ultrasound procedure using high-end ultrasound system with a 9-MHz broadband linear transducer. Two experienced readers analyzed the B-mode scans and mammograms using the BI-RADS criteria, while elastograms were analyzed using the Tsukuba score. SRs were calculated from a tumor-adjusted ROI and a comparable ROI placed in the lateral fatty tissue. The sensitivity, specificity, and cutoff values were calculated for SRs (ROC analysis). The median age was 53 years. The sensitivity and specificity were 85 %/ 60 % for B-mode scanning, 85 %/ 68 % for elastography, 78 %/ 62 % for mammography, and 95 %/ 74 % for SRs. An SR cutoff value of 2.27 (AUC 0.907) allowed significant differentiation (p < 0.001) between malignant and benign lesions. The quantitative SR calculation was superior to subjective interpretation of B-mode scans and sonoelastograms with a positive predictive value of 83 % versus 78 % and 74 %, and equal to mammograms. Strain ratio calculation contributes to the standardization of sonoelastography with high sensitivity and allows significant differentiation between benign and malignant breast lesions with a higher specificity compared to B-mode, subjective evaluation of elastography and mammography.