Five new polyester ligands were prepared by the condensation polymerization of diethylenetriaminepentaacetic dianhydride with PEG of various molecular weight (Mn).By the reaction of these macromolecular ligands with GdCl3·6H2O
the corresponding metal complexes were obtained.Preliminary results showed that the relaxivity of these macromolecular gadolinium complexes were higher than that of Gd(DTPA) which is widely used in clinical diagnosis.