Rational Design of a High Relaxivity MR Probe

Luca Frullano¹, Peter Caravan¹

The synthesis and characterization of a new Gd-based contrast agent is described. A dual strategy of increasing inner-sphere and second-sphere hydration was used to design an agent with more than 150% higher relaxivity than other low molecular weight contrast agents. Relaxivity is unaffected by the presence of coordinating anions such as phosphate or citrate and the high relaxivity is maintained over a broad field range (0.5 9.4T). This complex also contains a pendant carboxylate for linkage of this contrast agent to a putative targeting moiety such as a peptide.