Evaluation of Dendritic Gadolinium Complexes as MRI Contrast Agents

A series of dendritic gadolinium complexes based on dendrimers with 1,4,7,10-tetraazacyclododecane as the core were synthesized. Both diethylenetriaminepentaacetic acid and pyridoxamine were incorporated to the amine groups on the surface to give the dendritic ligands. These dendritic ligands were then reacted with gadolinium chloride to yield the corresponding dendritic gadolinium complexes. The dendritic ligands and their gadolinium complexes were characterized by HNMR, IR, UV and elemental analysis. Relaxivity studies showed that the dendritic gadolinium complexes have higher relaxation effectiveness than that of the clinically used small molecular gadolinium complexes. Magnetic resonance imaging of the liver in rats indicated that the dendritic gadolinium complex containing pyridoxamine enhances the image contrast of the liver, provides prolonged intravascular duration and produces highly contrasted visualization of blood vessels in the liver.