SYNTHESIS, CHARACTERIZATION AND COMPARATIVE-STUDY OF AMINOPHOSPHONATECHELATES OF GADOLINIUM(III) IONS AS MAGNETIC-RESONANCE-IMAGING CONTRAST AGENTS

Gadolinium(III) complexes of aminophosphonates, including a novel liga nd LH-4(8), have been investigated as potential contrast agents for NM R imaging. Water H-1 relaxivities at 10 and 200 MHz were determined an d luminescence measurements, on Tb(III) complexes, allowed the determi nation of the number of coordinated H2O molecules. The complexes bound strongly to hydroxyapatite, suggesting possible targetting to bone in vivo. This was confirmed by Gd-153 tracer studies with the most favou rable biodistribution in rats being shown by gadolinium(III) ediamine- N,N,N',N'-tetrakis(methylenephosphonate).