ACCUMULATION OF TC-99M-CYSTEINE IN EXPERIMENTAL INFLAMMATORY LESIONS IN COMPARISON TO TC-99M-GLUTAMINE AND TC-99M-HIG

Aim: The aim of this experimental work was to investigate the efficacy of Tc-99m-L-Cysteine (Cys) in scintigraphic visualization of inflamma tory lesions in comparison to Tc-99m-L-glutamine (G), and (99)mTc-HIG. Methods: In mice abscesses were induced by intramuscular injection of turpentine. Six days later mice were injected with 3.7 MBq of each ag ent and sacrificed in groups of three at 1, 3, 6 and 24 h. Scintigrams were obtained with a gamma camera. The organs, some blood, abscesses, some muscle and urine were removed, weighed and counted in a gamma co unter. Percentage of uptake by organs and per gram tissues and abscess /normal tissue concentration ratios were calculated. Experimental arth ritis was produced in 6 New Zealand rabbits by intraarticular injectio n of ovalbumin. Four days later 37 MBq of Tc-99m-Cys and Tc-99m-HIG we re each i.v. administered to 3 rabbits. Scintigrams obtained at 1, 3, 6, and 24 h demonstrated the arthritic joints very well. ROI's over ar thritic joints were compared to contralateral normal joints (A/C). Res ults: In mice the abscesses were well visualized on all scintigrams. T he maximum abscess/muscle ratios were 5.21 +/- 1.09 (6 h), 3.73 +/- 0. 81 (3 h) and 5.98 +/- 1.17 (24 h) and the maximum abscess/blood ratios were 3.46 +/- 1.33 (24 h), 1.81 +/- 0.10 (6 h) and 0.914 +/- 0.351 (2 4 h) for Tc-99m-Cys, Tc-99m-G, and Tc-99m-HIG, respectively. In rabbit s the maximum AIC ratios were 2.61 +/- 0.53 (3 h) and 2.92 +/- 0.99 (2 4 h) for Tc-99m-Cys and Tc-99m-HIG, respectively Conclusion: our resul ts indicate that Tc-99m-Cys is a promising agent for imaging inflammat ory lesions. It is preferred to Tc-99m-HIG, because of higher concentr ation ratios attained earlier, lower blood background, lower cost and a simpler in-house preparation method.