Comparative scintigraphic study of renal function with 99mTc-Mercaptoacetyl-triglycine and 99mTc-Ethylenedicysteine

99mTc-MAG3 is a standard radiotracer for renal dynamic functional study. Despite itsproperties for clinical uses, it has numerous technical limitations. 99mTc-EC is also a tubularradiotracer for renal imaging, which has not been used worldwide. In this study, the use of 99mTc-ECand 99mTc-MAG3 for renal functional study were compared. Thirty five patients (20 male, 15 female; mean age of 34.63 ±10.69 years) were entered inthe study. About 10 mCi of 99mTc-EC and 99mTc-MAG3 were administered in different days within 7days intervals and serial images were obtained for 30 minutes. Serum creatinine and visualscintigraphic findings of all patients were within normal limits. In this study, the renal uptake of 99mTc-EC was significantly higher than 99mTc-MAG3 (6.20%vs 4.39% of the injected dose), while the hepatic activity of 99mTc-EC was significantly lower (307 vs439 mean pixel count, p<0.0001). Also the absolute values for some other quantitative parameterssuch as right and left kidney transit times and ERPF were different for each radiotracer. In spite ofthese differences most quantitative parameters (except for right kidney transit time, liver uptake andTmax of both kidneys) showed good correlations for both agents. The calculated ERPF with 99mTc-EC as compared to 99mTc-MAG3 is in closer proximityto the true values. Also the use of 99mTc-EC compared to 99mTc-MAG3 in clinic due to simplicity ofpreparation, higher stability, higher renal uptake, and lower hepatobiliary activity is better. Thereforethe use of 99mTc-EC as an appropriate substitute or ever preferred radiopharmaceutical for 99mTc-MAG3 radiopharmaceutical for renal function studies is recommended.