Investigation of contrast-enhanced ultrasound findings for the differential diagnosis of small breast lesions

Abstract

Purpose Widespread ultrasound (US) screening is expected to increase the number of small breast masses that are found, making it difficult to differentiate between benign and malignant tumors. Miyamoto1 et al showed that contrast-enhanced ultrasound (CEUS) with perflubutane (Sonazoid®) has significantly higher accuracy and specificity in comparison with conventional US for the differential diagnosis of lesions Patients and methods A total of 109 patients with small breast lesions were enrolled from December 2012 to December 2018. The tumor diameter of all cases was ≤ 10 mm, and the pathological results were also known. Forty-one lesions were malignant, and sixty-eight lesions were benign on histopathology. The mean age of the malignant group was 56.0 years (range: 40-81 years), whereas the mean age of the benign group was 56.3 years (range: 30-79 years). The mean diameter of the malignant group was 6.6 mm (range: 2-10 mm) and that of the benign group was 6.7 mm (range: 3-10 mm). The enhancement pattern, including the intensity, type, and range of enhancement, as well as the time intensity curve for CEUS and the presence of internal vascularity on color flow images, was compared between the malignant and benign groups. Results There were few cases with breast imaging reporting and data system (BI-RADS) Category 4A or higher on mammogram (17.1% in the malignant group and 5.9% in the benign group). The rate of BI-RADS Category 4A or higher for conventional US was higher in the malignant group (65.9%) than in the benign group (47.1%). However, this difference was not significant. There was no difference between the malignant (39.0%) and benign (41.2%) groups in terms of the internal vascularity on color flow images. Therefore, CEUS was performed on the cases that were difficult to differentially diagnose. In the comparison of the enhancement pattern on CEUS, there was a significant difference only in the range of enhancement (P=.0001). In the multivariate analysis, the range of enhancement extending outward beyond the expected border of the lesion was a predictive factor for malignancy (P=.001). There was no difference in the other enhancement patterns. Conclusion In cases of difficult-to-diagnose small breast lesions, enhancement extending outward beyond the expected border of the lesion may be useful for differential diagnosis.