Technetium- and rhenium-labelled fatty acids as model compounds for myocardial metabolism imaging

In an attempt to develop new technetium-based radiopharmaceuticals for the non-invasive diagnosis of oxidative myocardial metabolism, rhenium model compounds according to the ‚3+1' mixed ligand approach as well as the organometallic tricarbonyl-design were synthesized. The geometrical impact of different chelates on the integrity of the fatty acid head structure was determined by single crystal X-ray analyses. To evaluate the diagnostic potential of the analogous Technetium-99m compounds, fatty acid complexes of the ‚3+1' mixed ligand type were prepared on n.c.a.-level and studied in the isolated constant-flow-perfused guinea pig heart model; compared to established [¹²³I]Iodine-labelled fatty acid radiotracers, the tested Technetium-99m derivatives showed a specific, however significantly lower myocardial extraction rate.