Comparison between Tc-99m N-NOET and Tl-201 in the assessment of patients with known or suspected coronary artery disease

Dithiocarbamate complexes as radiopharmaceuticals for medical imaging

Over the past 30 years dithiocarbamate ligands have found application in radiopharmaceutical metal-ligand complexes to image a range of disease states. The vast majority of research and applications, and the widest range of complex structures, have involved radionuclides of technetium and rhenium. Considering the extent of coordination chemistry of dithiocarbamate ligands described elsewhere in this issue, the extent of radiopharmaceutical application with metallic radionuclides is surprisingly narrow. Here we summarise the types of radiopharmaceutical complexes studied and the uses, and potential uses, to which they have been put in nuclear medicine.

Whole-body biodistribution and radiation dosimetry of the new cardiac tracer 99mTc-N-DBODC

Our purpose was to evaluate the safety profile and biodistribution behavior in healthy human volunteers of the new myocardial perfusion tracer bis[(dimethoxypropylphosphanyl)ethyl]ethoxyethylamine N,N'-bis(ethoxyethyl)dithiocarbamato nitrido technetium(V) (99mTc-N-DBODC).

METHODS

Ten healthy male volunteers were injected with 99mTc-N-DBODC under both stress and rest conditions. Anterior and posterior planar gamma-camera images were collected at 5, 30, 60, 240, and 1,440 min after injection, with organ uptake quantified by region-of-interest analysis. Tracer kinetics in body fluids were determined by collecting blood and urine samples at different time points.

RESULTS

After injection, 99mTc-N-DBODC showed significant accumulation in the myocardium and prolonged retention. Under rest conditions, uptake in the heart, lungs, and liver at 5 min after injection was 1.67% +/- 0.13%, 1.16% +/- 0.07%, and 10.85% +/- 1.72%, respectively, of administered activity. Under stress conditions, heart uptake was significantly higher (2.07% +/- 0.22%). Radioactivity in the liver decreased to 3.64% +/- 0.98% and 2.37% +/- 0.48% at 60 and 240 min, respectively, after injection. This rapid liver clearance led to favorable heart-to-liver ratios, reaching values of 0.74 +/- 0.13 at rest and 1.26 +/- 0.28 during exercise 60 min after tracer administration. Radiation dose estimates were comparable to those obtained with other myocardial perfusion cationic compounds.

CONCLUSION

The high uptake in the myocardium and the fast liver washout of 99mTc-N-DBODC will allow SPECT images of the left ventricle to be acquired early and with excellent quality.