Assessment of local recurrence after breast-conserving therapy with MRI.

PURPOSE The purpose of our study was to evaluate the relevance of MR mammography in the diagnosis of early and late tumor recurrence after breast-conserving therapy. METHOD Sixty-seven patients receiving breast-conserving therapy underwent 84 MR mammographies in a period between 1 month and 14 years after end of therapy. Dynamic measurements were made following application of contrast agent. The course of signal intensity changes was evaluated in focal lesions and irradiated and contralateral glandular tissue. RESULTS All 10 malignant lesions (7 local recurrences, 1 chest wall recurrence, 2 contralateral carcinomas) showed a > 75% increase in signal intensity within th first minute after contrast agent application. In all patients examined during the first year after end of therapy (n = 29), increased enhancement in irradiated parenchyma was observed compared with the contralateral breast, but only in two patients the increase was > 75% within the first minute. CONCLUSION Already in the first year after end of therapy, MRI can improve diagnostic accuracy in the assessment of breast cancer recurrence. More than 12 months following end of therapy, MR mammography can demonstrate tumor recurrence with a sensitivity of nearly 100% and a specificity rising to > 90% in differentiating tumor from therapy-induced changes.