MR quantification of abnormal stromal enhancement in the periphery of invasive breast tumors

Abstract

636 Background: In dynamic contrast-enhanced MRI (DCEMRI), properties of tissue microvasculature and overall vascularity can be quantified using kinetics of contrast enhancement. It has been shown that areas with high signal enhancement ratio (SER) were significantly correlated with high tumor vascularity, and that mean SER in nearby non-cancerous breast stroma was significantly associated with disease free survival. No universally accepted methods exist to determine the optimal extent of histologically normal breast tissue to treat. Although a relationship between normal tissue SER and recurrence has been observed, the spatial relationship of enhancement within the non-cancerous stroma with respect to proximity of the tumor has not been shown. We hypothesized that abnormalities in vasculature exist within the histologically normal breast stroma that can be detected by measuring changes in enhancement intensity. Methods: We performed a secondary analysis of pre-treatment DCEMRI data from 27 invasive breast cancer patients. An automated, user-independent program was used to segment breast tissue from all other structures. A SER threshold was set to identify invasive tumor regions, and a tumor proximity map was generated giving the 3D distance of each normal breast tissue voxel to the nearest tumor voxel. A percent enhancement (PE) map was calculated for the normal stroma using the signal intensity change between the pre-contrast and post-contrast images. The proximity and PE maps were then combined to measure breast tissue enhancement at various distances from the tumor. Results: PE levels in normal breast tissue situated within 2 cm of the tumor region were significantly higher than at all more distant regions. Pairwise comparisons with Turkey's adjusted p-values indicated that the mean PE at 0 cm-1 cm is significantly higher than all other distant levels (p = < 0.0001) and the mean PE at 1 cm-2 cm is significantly higher than 5 cm-6 cm (p = 0.006). Conclusions: Here, we show that the normal-appearing breast stroma within 0 cm to 2 cm of a primary tumor exhibits higher enhancement levels than stroma located far from the tumor. These results suggest that tissue surrounding the tumor region may contain tumor-related angiogenesis. These findings could help personalize surgery and radiation techniques. No significant financial relationships to disclose.