The choice of region of interest measures in contrast-enhanced magnetic resonance image characterization of experimental breast tumors

Objectives: The objectives of this study were to determine if magnetic resonance (MR) estimates of quantitative tissue microvascular characteristics from regions of interest (ROI) limited to the tumor periphery provided a better correlation with tumor histologic grade than ROI defined for the whole tumor in cross-section. Methods: A metaanalysis was based on 98 quantitative MR image breast tumor characterizations acquired in 3 separate experimental studies using identical methods for tumor induction and contrast enhancement. Results: The endothelial transfer coefficient (K-PS) of albumin (GdDTPA) from the tumor periphery correlated (r = 0.784) significantly more strongly (P < 0.001) with the pathologic tumor grade than K-PS derived from the whole tumor (r = 0.604). K-PS estimates, either from the tumor periphery or from the whole tumor, correlated significantly more strongly with histologic grade (P < 0.01) than MR image estimates of fractional plasma volume (fPV) from either tumor periphery (r = 0.368) or whole tumor (r = 0.323). Conclusions: K-PS estimates from the tumor periphery were the best of these measurable MR image microvascular characteristics for predicting the histologic grade.