Abstract #2910

Paquette B, Pellerin M, Tremblay L, Lepage M

Microscopic changes in the tumor tissue following radiotherapy occur before variations in shape and volume can be observed. In this study DCE-MRI was used to analyze changes in the microvasculature following the irradiation of mouse breast carcinomas. The transcapillary transfer rate shows a degradation of tissue perfusion that precedes the onset of necrosis and eventually, tumor regression. Diffusion from the tumor periphery rather than perfusion is responsible for the accumulation of contrast agent in the necrotic tumor core. This gives rise to artificially high values of ve