TECHNETIUM-99M-N,N-ETHYLENEDICYSTEINE - A COMPARATIVE-STUDY OF RENAL SCINTIGRAPHY WITH TECHNETIUM-99M-MAG3 AND IODINE-131-OIH IN PATIENTS WITH OBSTRUCTIVE RENAL-DISEASE

Technetium-99m-labeled N,N-ethylenedicysteine (Tc-99m-EC) is a new ren al imaging agent introduced as an alternative for Tc-99m-labeled merca ptoacetyltriglycine (Tc-99m-MAG3), with similar renal excretion charac teristics. To evaluate the diagnostic characteristics of this agent, a gamma camera study was performed. Methods: Sixteen patients with obst ructive renal disease and six normal controls were injected with 90 to 110 MBq of Tc-99m-EC and 7.4 MBq (131)l-labeled orthoiodohippurate (O IH). Serial images were obtained during 20 min for Tc-99m-EC and 30 mi n for OIH. The study was repeated using 90 to 110 MBq (TC)-T-99m-MAG3 during the same week. Results: Renograms, functional ratios and urinar y excretion patterns of all three agents were similar. The mean time t o peak activity values for OIH, Tc-99m-EC and Tc-99m-MAG3 were 4.25 a 0.37 min, 4.39 +/- 0.32 min and 4.00 a 0.24 min, respectively. The tim e from peak to 50% activity values for OIH, Tc-99m-EC and Tc-99m-MAG3 were 5.48 a 0.80 min, 6.93 a 0.69 min and 7.33 a 0.85 min, respectivel y. Conclusion: it is concluded that (TC)-T-99m-EC has excellent imagin g characteristics and similar excretion properties to OIH. The advanta ges of Tc-99m-EC over (TC)-T-99m-MAG3 are lower hepatobiliary uptake a nd simplicity of preparation.