Ren W Elmer A Buehlmann D Augath MA Vats D Ripoll J Rudin M 2016 PURPOSE Assessing tumor vascular features including permeability and perfusion is essential for diagnostic and therapeutic purposes. The aim of this study was to compare fluorescence and magnetic resonance imaging (MRI)-based vascular readouts in subcutaneously implanted tumors in mice by simultaneous dynamic measurement of tracer uptake using a hybrid fluorescence molecular tomography (FMT)/MRI system. PROCEDURE Vascular permeability was measured using a mixture of extravascular imaging agents, GdDOTA and the dye Cy5.5, and perfusion using a mixture of intravascular agents, Endorem and a fluorescent probe (Angiosense). Dynamic fluorescence reflectance imaging (dFRI) was integrated into the hybrid system for high temporal resolution. RESULTS Excellent correspondence between uptake curves of Cy5.5/GdDOTA and Endorem/Angiosense has been found with correlation coefficients R > 0.98. The two modalities revealed good agreement regarding permeability coefficients and centers-of-gravity of the imaging agent distribution. CONCLUSION The FMT/dFRI protocol presented is able to accurately map physiological processes and poses an attractive alternative to MRI for characterizing tumor neoangiogenesis. https://sonar.ch/global/documents/265983 eng info:eu-repo/semantics/altIdentifier/doi/10.1007/s11307-015-0884-y info:eu-repo/semantics/altIdentifier/pmid/26381672 Molecular imaging and biology. - 2016 Fluorescence molecular tomography MRI Perfusion Simultaneous hybrid measurements Tumor angiogenesis Vascular permeability Animals Capillary Permeability Female Fluorescence Magnetic Resonance Imaging Mice, Inbred BALB C Mice, Nude Neoplasms Perfusion Dynamic Measurement of Tumor Vascular Permeability and Perfusion using a Hybrid System for Simultaneous Magnetic Resonance and Fluorescence Imaging. http://purl.org/coar/resource_type/c_6501