MR imaging of response to primary chemo-brachytherapy in BCT-inoperable breast cancer.

Purpose: To evaluate (1) if neoadjuvant chemo-brachytherapy interferes with MR imaging, (2) if MR can predict the size of the remaining tumor after th erapy and (3) if MR can give prognostic information after the onset of ther apy. Materials/Methods: 14 patients enrolled in a preoperative tumor-reduct ion protocol (4 cycles of chemotherapy combined with interstitial radiother apy) were examined by dynamic contrast enhanced MR mammography (1 T, tempor al resolution 93 s, spatial resolution 1.9 min, 0.1 mmol/kg GdDTPA), before therapy, after the first two cycles of chemotherapy, after radiotherapy an d the third cycle, and after completion of therapy. MR findings were evalua ted for (1) artificial enhancement after radiotherapy, (2) correlation of e nhancement after therapy with histology and (3) changes in enhancement dyna mics after the first 2 cycles. Results: (1) 54% of patients had diffuse enh ancement that occurred after radiotherapy but vanished before the end of th erapy. (2) 4 patients had complete histological remissions after therapy, 3 had dispersed single tumor cells, 7 had remaining nodular tumor. While MR could not differentiate between complete remission and single tumor cells, it accurately predicted the diameter of remaining nodular tumor, except for one case that showed false-positive enhancement. (3) MR dynamics after the first cycles of chemotherapy could not predict overall response. Conclusio ns: MR is an accurate tool in assessing tumor response after neoadjuvant ch emobrachytherapy. Negative effects from radiotherapy are only transient.