Differentiation between benign and malignant breast tumors using kinetic features of real-time harmonic contrast-enhanced ultrasound

BACKGROUND: Contrast-enhanced ultrasound (CEUS) has gained interest because of its ability to gather vascular information in diverse organs. There is still a subject of debate concerning its value in breast lesions, especially as a differential diagnostic tool. PURPOSE: To investigate whether kinetic parameters of CEUS can differentiate between malignant and benign breast lesions. MATERIAL AND METHODS: We evaluated 75 malignant and 21 benign lesions in the breast or axilla. Contrast harmonic imaging (CHI) US was performed after the injection of a bolus dose of 2.4 mL of Sono Vue® (Bracco, Milano, Italy). The following parameters were calculated for kinetic analysis: initial slope, time to peak enhancement, wash-out ratios W(21) and W(50) (relative decrease in signal intensity from the peak enhancement to 21 s and 50 s, respectively). RESULTS: A significant difference was found between the benign and malignant lesions in time-to-peak (P value <0.05) and wash-out ratios W(21) (P value <0.001) and W(50) (P value <0.001). The mean time-to-peak was 9.3 s for malignant and 14.6 s for benign lesions. The mean signal drop from peak to signal intensity measured at 50 s was 85% for malignant and 66% for benign lesions. There was no difference in absolute values of peak signal intensity and initial slope. The most significant difference between standardized benign and malignant wash-out curves was found at 21 s but statistical significance was reached in the range of 14-50 s. CONCLUSION: Real-time CEUS can evolve into a new non-invasive option for differentiate malignant from benign breast lesions.