Magnetic resonance imaging relaxation agents

The commercial development of Gd(dota) as a magnetic resonance imaging relaxation agent, as well as the demonstrated ability of lanthanide complexes to catalytically cleave RNA, have stimulated research into the synthesis of complexes derived from macrocyclic ligands with pendant arms. NMR studies have been carried out on many of the paramagnetic complexes derived from this class of ligands, which are reviewed in the following sections. 

Keywords Metallofullerene, endohedral, gadolinium, magnetic resonance imaging, contrast agent, relaxivity, cellular imaging, molecular imaging... 

Toth E, Helm L, Merbach AE (2001) Relaxivity of Gadolinium(III) Complexes theory and mechanism. In Toth , Merbach AE (eds.) The chemistry of contrast agents in medical magnetic resonance imaging. Wiley, Chichester, pp. 45-119. 

Rongved, P. and Klaveness, J., Water-soluble polysaccharides as carriers of paramagnetic contrast agents for magnetic resonance imaging synthesis and relaxation properties, Carbohydrate Res., 214, 315-323, 1991. 

The gadolinium complex with Cxi displays a reasonable relaxivity and it has been assessed as a potential contrast agent for magnetic resonance imaging. Its stability constant is however too low to make this complex a good candidate for in vivo applications. Until now, no calixarene derivative has proved efficient in this field, contrary to the pendant-arm substituted coronands. 

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