Targeted magnetic resonance imaging agents for the detection of physiological processes

An MRI agent composition comprising:

• a) a first Gd(III) ion bound to a first chelator such that said first Gd(III) ion has coordination atoms in at least 7 coordination sites of said first Gd(III) ion;
• b) a first blocking moiety covalently attached to said first chelator which hinders the rapid exchange of water in the remaining coordination sites of said first Gd(III) ion;
• and
• c) at least a first targeting moiety;
• wherein said first blocking moiety is attached such that interaction of said first blocking moiety with a target substance increases the exchange of water in the remaining coordination sites of said first Gd(III) ion.