Magnetic resonance imaging (MRI) is a commonly used diagnostic method in medicinal practice as well as in biological and preclinical research. MRI provides detailed images of the body and often represents the only reliable diagnostic method for conditions such as multiple sclerosis and cranial problems. 

Contrast agents (CA) are materials which can be injected into the body to provide an enhanced MRI image. In clinical practice, more than 35% of MRI examinations are performed with the use of CAs. Gadolinium chelates are the most commonly used contrast agent. The first example of a modern MRI CA is considered to be the gadolinium(III) complex of DTPA which was approved for clinical usage in 1988. 

In their Dalton Transactions Perspective, Ivan Lukes and colleagues at the Universita Karlove in the Czech Republic discuss CAs based on gadolinium(III) complexes and on the coordination chemistry that controls their properties. 'This a large field, open for modification of the known CAs and for testing new ones,' says Lukes.