Enhanced substrate imaging by reversible binding to a paramagnetic complex

A method of obtaining images comprising:

• administering a paramagnetic chelate complex comprising a lanthanide metal ion with atomic number ranging from 58 to 70, or a transition metal ion with atomic number from 21 to 29 and from 42 and 44 and a chelating ligand selected from, 10-[(3-methoxyphenyl)methyl]-1,4,7,10-tetraazaciclododecane-1,4,7-tris-[(aminocarbonyl)methyl], and 10-[(3-methoxyphenyl)methyl]-1,4,7,10-tetraazaciclododecane-1,4,7-triacetic acid, or a physiologically acceptable salt thereof, which non covalently binds with a binding strength of at least 10M-1 to a substrate molecule, thereby shortening the relaxation times of the magnetic nuclei of the substrate molecule by forming a non-covalent reversible binding between the substrate and the paramagnetic chelate complex and
• registering the image of the substrate molecule in a human or animal body organ or tissue by use of the Magnetic Resonance Imaging techniques,
• wherein said image is obtained in vivo and
• wherein said substrate molecule is an endogenous substrate selected from lactate, citrate, carbonate, phosphate, pyruvate, natural amino-acids, oxalate, tartrate, succinate, choline, creatine, acetate, and malonate in a human or animal body organ or tissue.