Experimental study of [99mTc(PNP5) (DBODC)]+ as a new myocardial perfusion imaging agent

This study was aimed to compare the properties of [(99m)Tc(PNP5)(DBODC)]+ with (99m)Tc-MIBI in normal swine and in canine models of myocardial ischemia.

Seven anesthetized swine were injected intravenously with [(99m)Tc(PNP5)(DBODC)]+. Serial planar images were acquired meanwhile. Twelve adult dogs were studied. A critical stenosis of left anterior descending artery was produced. [(99m)Tc(PNP5)(DBODC)]+ or (99m)Tc-MIBI (randomly) was injected intravenously at the end of 3 min of adenosine infusion. The occluder was released after adenosine infusion. Myocardial SPECT imaging was obtained at 30, 60, 90 and 180 min, respectively, after tracer injection. Rest myocardial SPECT imaging was acquired on the next day.

Blood disappearance of [(99m)Tc(PNP5)(DBODC)]+ was biexponential with an initial half-time of 2.97 +/- 0.48 min and a late half-time of 52.49 +/- 19.49 min. Myocardial [(99m)Tc(PNP5)(DBODC)]+ uptake was similar to (99m)Tc-MIBI. Heart-to-liver ratio of [(99m)Tc(PNP5)(DBODC)]+ was significantly higher than that of (99m)Tc-MIBI (0.99 +/- 0.03 vs. 0.46 +/- 0.10, p < 0.05) 30 min after injection. In canine models of myocardial ischemia, image quality of [(99m)Tc(PNP5)(DBODC)]+ was better than (99m)Tc-MIBI. Segments with perfusion defects by [(99m)Tc(PNP5)(DBODC)]+ was 3.60 +/- 1.52 and 4.25 +/- 0.96 by (99m)Tc-MIBI (p = n.s.).

[(99m)Tc(PNP5)(DBODC)]+ seems to be a promising new myocardial perfusion imaging agent.