Design and Optimization of Gadolinium Based Contrast Agents for Magnetic Resonance Imaging

Abstract: The role of Gd3+ chelates as contrast agents in Magnetic Resonance Imaging is discussed. The theory describing the different contributions to paramagnetic relaxation relevant to the understanding of the molecular parameters determining the relaxivity of those Gd3+ chelates, is presented. The experimental techniques used to obtain those parameters are also described. Then, the various approaches taken to optimize those parameters, leading to maximum relaxivity (efficiency) of the contrast agents, are also ilustrated with relevant examples taken from the litterature. The various types of Gd3+-based agents, besides non-specific and hepatobiliary agents, are also discussed, namely blood pool, targeting, responsive and paramagnetic chemical shift saruration transfer (PARACEST) agents. Finally, a perspective is presented of some of the challenges lying ahead in the optimization of MRI contrast agents to be useful in Molecular Imaging.