[Ultrasonography contrast media Levovist and power Doppler in the study of the breast. Methodology, vascular morphology and automatic enhancement quantification with wash-in and wash-out curves].

PURPOSE

To define the technique for contrast-enhanced power Doppler US studies of breast lesions and to identify possible clinical applications.

MATERIAL AND METHODS

We studied 51 breast lesions detected at mammography and confirmed at cytology and/or surgical biopsy; 15 were benign lesions and 36 carcinomas, namely 14 T1ab, 29 T1c and 8 T2. We found 14 masses with regular margins, 28 with irregular margins, 1 asymmetric density, 2 architectural distortions and 6 clustered calcifications. US studies were performed with an AU5 Harmonic unit (Esaote Biomedica, Genoa, Italy) equipped with a software for online image storage, analysis and automatic quantification of US signal intensity changes after contrast agent injection, namely wash-in and wash-out contrast enhancement curves. The echocontrast agent Levovist (Schering AG, Berlin, Germany), 4.0 g preparation, was administered by i.v. injection (cubital vein) in two times at a concentration of 400 mg/mL. The first 4 mL of Levovist suspension were injected as a bolus at approximately .5 mL/s to evaluate lesion vascularization and choose the best scanning plane for wash-in and wash-out quantification. The remaining 6 mL of Levovist suspension were injected at approximately 1.0 mL/s and dedicated to wash-in and wash-out recording.

RESULTS

The region of interest could not be identified in 2 of 6 calcifications. After Levovist administration, signal enhancement was seen in 36 lesions. Nonsignificant curves were obtained in 7 fibroadenomas, 1 fibrocystic mastopathy and 5 carcinomas. Pathology diagnosed an in situ component around the lesion core (true positives) in 12 carcinomas with perilesional vessels and also 3 more carcinomas with perilesional foci in situ missed at contrast-enhanced US (false negatives). The wash-in/wash-out curves of 30 carcinomas differed from those of the 6 fibroadenomas, in that the former had faster wash-in and an earlier enhancement peak, as well as longer enhancement than the latter. Moreover, fibroadenoma curves are regularly increasing, with moderate variations. As for wash-out, carcinomas exhibited three main patterns, namely a monophasic, a polyphasic and a plateau pattern.

DISCUSSION

The pattern of enhancement curves in fibroadenomas is related to straight and regular vessels, while arteriovenous shunts in carcinomas cause early signal intensity peaks. Wash-out is longer in carcinomas than in fibroadenomas because the former present anarchic and tortuous vessels with slow flows.

CONCLUSIONS

Levovist enhanced US is a complementary test to study known breast lesions which permits the differential diagnosis of carcinomas and fibroadenomas. Our results justify a larger clinical trial to assess the role of this technique for diagnosis, prognosis and staging purposes.