Purpose: Preclinical dynamic MRI on tumor models is typically performed with gradientor spin-echo sequences and Cartesian k-space sampling which is not optimal for tumors affected by respiratory motion (e.g. spontaneous tumors in transgenic mice). In these cases, radial k-space sampling, rather insensitive to motion, should be more appropriate. Furthermore, simultaneous dynamic T1 and T2* assessment has been recently shown to be of interest to characterize vasculature of tumors at high magnetic field (1). A 2D radial multi gradient echo sequence with fast T1 and T2* quantification was previously developed and validated in vitro and in vivo in tumor bearing “freely breathing” anaesthetized mice (2). The purpose of this work was to extend the radial sequence to 3D and to perform a first in vivo study comparing 3D K maps of motion animated subcutaneous tumors for two contrast agents (CA) of different molecular weights (MW) and structures.