Dynamic breast MRI in the course of neoadjuvant chemotherapy: standardized evaluation of tumor size and enhancement parameters in correlation to different histopathologic characteristics.

RATIONALE AND OBJECTIVES: Basic exploratory data analysis to evaluate enhancement and tumor size (SIZE) in contrast-enhanced breast magnetic resonance imaging (CE-MRI) during chemotherapy. Correlation with histopathology (human epidermal growth factor receptor (HER2/neu) status and estrogen receptor (ER) score). MATERIALS AND METHODS: Sixty-five women (mean age 47 +/- 10 years) with locally advanced breast cancer (mean SIZE 25 mL) had CE-MRI (three-dimensional fast low angle shot (FLASH); repetition time = 9.1 ms, echo time = 4.8 ms, flip angle (FA) 25 degrees, matrix size 256 x 256 pixels, field of view 350 mm, slice thickness 2 mm, number of slices = 32, one precontrast and five postcontrast series) before and after chemotherapy. Lesion segmentation and subsequent SIZE and enhancement analysis including maximum enhancement (MAX), area under the curve (AUC), time-to-peak (TTP), and maximum upslope (MUS) were performed. Correlation with histopathology (ER score and HER2/neu status). RESULTS: SIZE reduced significantly during therapy (25 mL vs. 5 mL, P < .0001). AUC, MAX, MUS decreased (P < .0001), TTP increased (P < .0001). SIZE and MAX were independent parameters (r(2) = .22). No correlation (P > .01) in any of the parameters with either ER score or HER2/neu status was found. HER2/neu score equal 2+pos. or 3+ showed significantly stronger changes in SIZE (P < .01), MAX (P < .01) and AUC (P < .05) compared to lower HER2/neu score (0 to 2+neg.). CONCLUSIONS: From routine MRI protocol and semiquantitative analysis of signal enhancement curves, information about size, and hemodynamic status of tumors under treatment may be extracted. Reduction in size and maximum enhancement were complementary parameters. In the course of therapy, size and enhancement may develop differently in clinically relevant histopathological subgroups.