Optimized time‐resolved imaging of contrast kinetics (TRICKS) in dynamic contrast‐enhanced MRI after peptide receptor radionuclide therapy in small animal tumor models

Anti‐tumor efficacy of targeted peptide‐receptor radionuclide therapy (PRRT) relies on several factors, including functional tumor vasculature. Little is known about the effect of PRRT on tumor vasculature. With dynamic contrast‐enhanced (DCE‐) MRI, functional vasculature is imaged and quantified using contrast agents. In small animals DCE‐MRI is a challenging application. We optimized a clinical sequence for fast hemodynamic acquisitions, time‐resolved imaging of contrast kinetics (TRICKS), to obtain DCE‐MRI images at both high spatial and high temporal resolution in mice and rats. Using TRICKS, functional vasculature was measured prior to PRRT and longitudinally to investigate the effect of treatment on tumor vascular characteristics. Nude mice bearing H69 tumor xenografts and rats bearing syngeneic CA20948 tumors were used to study perfusion following PRRT administration with 177lutetium octreotate. Both semi‐quantitative and quantitative parameters were calculated. Treatment efficacy was measured by tumor‐size reduction. Optimized TRICKS enabled MRI at 0.032 mm3 voxel size with a temporal resolution of less than 5 s and large volume coverage, a substantial improvement over routine pre‐clinical DCE‐MRI studies. Tumor response to therapy was reflected in changes in tumor perfusion/permeability parameters. The H69 tumor model showed pronounced changes in DCE‐derived parameters following PRRT. The rat CA20948 tumor model showed more heterogeneity in bo...
Source: Contrast Media and Molecular Imaging - Category: Radiology Authors: Tags: Full Paper Source Type: research