Benign and Malignant Breast Lesions: Efficacy of Real Time Contrast-Enhanced Ultrasound vs. Magnetic Resonance Imaging

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To assess the efficacy of low mechanical index (MI) real time grey scale contrast-enhanced US (CEUS) in the differentiation of breast lesions in comparison to Magnetic Resonance Imaging (MRI). 50 lesions previously detected at mammography or conventional US were evaluated by means of CEUS and MRI. Contrast-enhanced examinations were performed with a dedicated equipment (Esatune, Esaote, Genoa, Italy), before and after injection of 4.8 ml of Sonovue (Bracco, Milan, Italy). MRI was conducted with a 1.5 T equipment (Siemens Vision Plus, Erlangen, Germany) with bilateral dedicated superficial coil, on T2w STIR and 3D Flash T1w before and 1, 2, 3, 4, 5 minutes after the administration of contrast agent (Gd-DTPA, 1.5 ml/kg). Wash-in and wash-out curves were assessed for both procedures. A specific sonographic quantification software (Qontrast, Bracco, Milan, Italy), based on pixel by pixel signal intensity over time, was used to obtain contrast-enhanced sonographic perfusion maps for each lesion. Mc Nemar test was then calculated. 24 invasive ductal carcinomas, 18 fibroadenomas, 4 fibro-cystic dysplasias, 1 mucinous carcinoma, 1 invasive ducto-lobular carcinoma, 1 intraductal florid papillomatosis and 1 phylloides tumour were diagnosed. Contrast-enhanced sonographic patterns correlated well with those provided by MRI. Sensitivity, specificity, and accuracy of US were: 69.2 %, 66.7 %, and 68 %, respectively. According to the different contrast enhancement patterns and the resulting perfusion maps, all the malignant lesions and 9 out of 12 benign lesions were correctly diagnosed, thus resulting in 87.5 % of specificity and 100 % of sensitivity. Regarding the specificity, there is no difference between US and CEUS with McNemar (p = 0.18). Regarding sensitivity, the difference between contrast-enhanced US and US is significant as calculated with McNemar test (p = 0.013). The three lesions which were incorrectly classified as malignant were two hypervascularised fibroadenomas in young women and a phylloides tumour. CEUS seems to be a reliable method to differentiate breast lesions, since it provides typical enhancement patterns. Contrast sonographic perfusion curves correlate well with MRI wash in--wash out curves.