RESUMO
OBJECTIVES: To evaluate ultrasound elastography (USE) using strain ratio (SR), a relative quantification approach for breast lesions characterization. METHODS: One hundred forty-seven consecutive patients with a total of 156 breast lesions underwent USE. Technical accuracy was assessed automatically. For SR evaluation a rounded ROI was depicted inside fat (F), glandular tissue (G) and inside the lesion (L), preferably at the same depth. R1, mean value of the G and F ratio, stands for in background tissue composition elasticity. R2; mean value of L/F stands for in lesion elasticity, both evaluated in arbitrary unit (au). Two-years follow-up and pathology results were standard of reference. Mann-Whitney test, ROC analysis and Chi-square with Yates correction were used. RESULTS: With the exception of 27 cysts, 17 malignant and 112 benign lesions were found. R1 values were 1.6±0.7au and 1.2±0.9au (p=0.015 NS); R2 values were 6.1±2.5au and 1.9±1.3au (p<0.001) for malignant and benign lesions, respectively. A threshold of 3.3au showed a sensitivity and specificity of 88% and 87%, respectively with an AUC of 93%. Fifteen false positive and two false negative were detected. CONCLUSION: Relative quantification of ultrasound elastography allows to find high levels of diagnostic accuracy in characterizing breast tumors above all in downgrading BI-RADS 3 and 4 lesions.