Gadolinium complexes agent

Future Applications. The use of gadolinium complexes as contrast agents in magnetic resonance imaging (mri) is growing (40). 

A second class of MRI contrast agents contains ligands that are derivatives of the macrocydic tetramine, 1.4.7.10-tetraazacyclododecane (cyclen). Gadoterate (Dotarem, Gd-DOTA, Scheme 3, formula 5) was the first macrocydic gadolinium complex which has entered the market. 

Neutral bis-and tris-gadolinium complexes of the oligomeric ligands have been obtained in the usual manner with gadolinium oxide and the corresponding dysprosium complexes by reaction with dysprosium oxide The latter might be useful as X-ray contrast agents. 

Furthermore, this lysine dendrimer-bound gadolinium complex exhibits a higher in-vivo stability as a contrast agent and hence a longer residence time in tissue than comparatively simple commercially available gadolinium compounds and thus assures improved visualisation of organs, blood vessels, and tissue (Fig. 8.18) [58],... 

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. 

The synthesis and study of gadolinium complexes as potential magnetic resonance imaging agents is of intense interest at the moment, and is discussed in the section on MRI in Section 5.5.2. 

The potentially octadentate DTPA likewise forms stable complexes. These have lately attracted considerable interest with the use of its gadolinium complex as a contrast enhancing agent for body scanners (MRI, see Metal-based Imaging Agents), probably the most important new... 

Medical applications are so far limited in number, but gadolinium complexes of DTPA and other hgands have become highly important injectible MRI contrast agents (see Metal-based Imaging Agents). The luminescent properties of the lanthanides are becoming exploited in luminescent sensors and bioassays. 

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