Synthesis and biodistribution of 99mTc-carbonyltechnetium-labeled fatty acids

In order to image myocardial metabolism, 99mTc(CO)3+ complexes containing fatty acids were evaluated. At first, 11-(1-imidazolyl)-undecanoic acid (IUA) and 11-(2-(4-bromo-phenylazo)-1-imidazolyl)-undecanoic acid (BPIUA) were synthesized and the corresponding carbonyltechnetium-labeled complexes were prepared. However, unfortunately similar to those of other technetium-labeled fatty acid analogs, the biodistribution studies of 99mTc(CO)3–IUA and 99mTc(CO)3–BPIUA in mice demonstrated poor heart-to-blood ratios, thus these complexes cannot be used as heart-imaging reagents. In addition, Tween-80 can improve the biodistribution of the complexes for myocardial imaging.