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

UNLABELLED 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.