Simultaneous PET/MRI assessment of response to cytotoxic and hormone neo-adjuvant chemotherapy in breast cancer: a preliminary report

The aim of this study was to assess the response to cytotoxic and hormone neo-adjuvant chemotherapy in four patients with locally advanced breast cancer by simultaneous PET/MRI. Four patients with locally advanced breast cancer underwent simultaneous PET/MRI of the breast using a 3 T Biograph mMR before and after neo-adjuvant chemotherapy (two patients were treated with hormone-therapy and two patients were treated with cytotoxic chemotherapy). Morpho-structural tumoral features and tumor size were assessed; area value, metabolic (SUV and MTV) and functional (ADC, K _trans, V _e, k _ep and iAUC) data were obtained by positioning regions of interest. A comparison of all parameters between the pre- and post-treatment PET/MRI examinations and between the two different therapeutic schedules was assessed. In patients treated with cytotoxic chemotherapy and classified as PR, there was a significant reduction of post-treatment morphological, metabolic and functional parameters. In a patient treated with hormone therapy, classified as SD, there was an increase of all post-treatment perfusion parameters, a substantially stable ADC value and a poor reduction of lesion size and of maximum SUV (SUV_max) values; the last patient, treated with hormone therapy and classified as PR, showed a significant reduction of lesion size and SUV_max values with a reduction of perfusion parameters and substantially stable ADC values. Multiparametric evaluation with simultaneous PET/MRI could be a useful tool to assess the response to cytotoxic and hormone neo-adjuvant chemotherapy in patients with breast cancer. Future studies in a larger cohort of patients are warranted to confirm the results of this preliminary study.