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Contrast enhanced harmonic ultrasound for differentiating breast tumors - first results.

PURPOSE
To investigate the extent to which indeterminate lesions of the breast can be differentiated in the early and late phase after bolus injection of the ultrasound contrast medium Optison.


MATERIALS AND METHODS
Fifty female patients (mean age: 49 years) with a altogether 53 preoperatively impalpable indeterminate breast tumors, 20 fibroadenomas and 33 carcinomas, were examined by B-mode imaging and contrast medium-enhanced ultrasound with power Doppler (three patients had multifocal carcinomas). The tumors had a diameter of 5-15 mm (mean diameter: 9 mm). Histological confirmation was performed in all lesions by vacuum biopsies and/or surgical preparation. All examinations were performed with a multifrequency linear array probe (5-10 MHz, Logiq9 and Logiq 7, GE). Power Doppler (PD) and B-mode imaging as well as tissue harmonic imaging (THI) were employed. A bolus of 0.5 ml Optison was injected intravenously and spreading of the contrast enhancement and washout in the tumors were followed for at least 20 minutes. A low mechanical index was chosen to avoid early destruction of the microbubbles. Maximum tumor size was measured and tumors vessels were evaluated in digital cine ultrasound sequences.


RESULTS
Without CM administration, 14 of 19 tumor lesions smaller than 10 mm could be distinguished better from the surrounding tissue with THI compared to fundamental B-mode imaging. Both benign (17/20) and malignant (30/33) tumors exhibited increased tumor marginal vessels or intratumoral vessels in the early phase after CM injection. A diffuse contrast medium accumulation was observed in the late phase (8-18 min, mean: 12 min) in 30 of 33 malignant tumors, but in none of the benign tumors. The diagnostic confirmation for this late enhancement was there with 90% for the malignant tumors.


CONCLUSION
After intravenous bolus administration of Optison, breast carcinomas appear to have a prolonged diffuse enhancement of central tumor vasularity in the late phase compared to an earlier marginal vascularity of fibroadenomas.