Second sphere complexes as relaxation agents for image enhancement in magnetic resonance imaging

A method for performing magnetic resonance imaging of a patient, comprising:

• a) providing a second sphere contrast enhancing agent, comprising a highly charged hydrophilic complex having a charge of three minus or greater which consists of a paramagnetic metal ion and at least one 1,2-dihydroxybenzene catecholate ligands coordinated thereto,
• b) administering the second sphere contrast enhancing agent to the patient;
• c) forming one or more hydrogen bonds between the paramagnetic metal ion-to-ligand linkage and tissue water molecules of the patient;
• and
• d) subjecting the patient to nuclear magnetic resonance imaging.

A second sphere contrast enhancing agent for magnetic resortames imaging of tissue, comprising:

• a) a paramagnetic metal ion selected (III) and gadolinium (III);
• b) at least one 1,2-dihydroxybenzene catecholate ligand coordinated to said paramagnetic metal ion to form a highly charged hydrophilic complex having a charge of three minus or greater, said catecholate ligands prepared from the salt disodium-1,2-dihydroxybenzene-3,5-disulfonate end forming bonding sites for hydrogen bonding where such hydrogen bonding sites include heteroatoms which form paramagnetic metal ion-to-ligand linkages;
• and
• c) water molecules hydrogen bonded to the bonding sites of said catecholate ligands.