[Magnetic resonance mammography in suspected tumor recurrences]

Twenty patients with clinically suspected breast cancer recurrence underwent MRI before and after paramagnetic contrast agent administration (MR mammography, MRM), after negative (4/20), questionable (11/20) or positive (5/20) X-ray mammography (XM). Spin-echo T1-weighted images before and after the i.v. administration of Gd-DTPA (0.15 mmol/kg) were acquired at 1, 3, 5, 7 and 10 minutes. Tissue behavior was studied directly on the images (qualitative analysis) and with dynamic curves of the signal-to-noise ratio and of enhancement rate (quantitative analysis). The histologic examination was performed in all cases--18 of them by surgical excision and in two by needle biopsy only. Seven of seven recurrences exhibited early (at 1 and 3 minutes) and focal qualitative enhancement, exceeding 100% at the quantitative analysis. Twelve of thirteen non-recurrences exhibited no significant qualitative enhancement, less than 40% at the quantitative analysis, while the extant lesion exhibited multifocal delayed (at 5-10 minutes) qualitative enhancement, about 60% at the quantitative analysis, and slight bilateral diffuse enhancement (proliferative dysplasia). MRM had 100% sensitivity, 92.3% specificity, 87.5% positive predictive value and 100% negative predictive value. XM had 100%, 30.8%, 43.7% and 100%, respectively (if we consider as positive all the questionable XM cases). To conclude, MRM is confirmed as a useful imaging technique in suspected breast cancer recurrences, especially after questionable XM exams.