DYNAMIC MR-IMAGING OF INVASIVE BREAST-CANCER - CORRELATION WITH TUMORGRADE AND OTHER HISTOLOGICAL FACTORS

The purpose of this study was to explore the association between dynam ic MR enhancement characteristics and histopathological prognostic fac tors of invasive breast cancer. 53 women with primary invasive breast cancer underwent dynamic contrast enhanced breast MRI. Region of inter est (ROI) analysis was performed on synthetic images obtained by kinet ic modelling of the dynamic data. Operator-defined, large ROIs and com puter-defined, 9-pixel ROIs were selected for each tumour. The relativ e increase in mean ROI pixel intensity was expressed in the form of en hancement ratios. Univariate and multivariate analyses were performed to explore the association of these ratios with standard histological factors, including tumour size, histopathological classification, hist ological grade, the presence of extensive in situ component and lympho vascular invasion, multifocal disease, and axillary lymph node status. All enhancement ratios showed significant differences between node-po sitive and node-negative tumours (max. p=0.002). However, automated RO I ratios showed less overlap between node-positive and node-negative c arcinomas than did large ROI ratios. A strongly significant associatio n was observed between all automated ROI enhancement ratios and histol ogical tumour grade (max. p=0.001). Based on stepwise multiple regress ion analysis, node status and histological grade were the only histopa thological factors with a significant independent effect on the enhanc ement characteristics. In summary, there is a strong association betwe en dynamic MR characteristics and two important prognostic markers of invasive breast cancer, namely axillary node status and histological g rade. This may allow MRI to be used in pre-operative predictions of tu mour behaviour and biological activity.