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

Abstract

99mTc-MAG3 is a standard radiotracer for renal dynamic functional study. Despite its
properties for clinical uses, it has numerous technical limitations. 99mTc-EC is also a tubular
radiotracer for renal imaging, which has not been used worldwide. In this study, the use of 99mTc-EC
and 99mTc-MAG3 for renal functional study were compared.
Methods: Thirty five patients (20 male, 15 female; mean age of 34.63 ±10.69 years) were entered in
the study. About 10 mCi of 99mTc-EC and 99mTc-MAG3 were administered in different days within 7
days intervals and serial images were obtained for 30 minutes. Serum creatinine and visual
scintigraphic findings of all patients were within normal limits.
Results: 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 vs
439 mean pixel count, p<0.0001). Also the absolute values for some other quantitative parameters
such as right and left kidney transit times and ERPF were different for each radiotracer. In spite of
these differences most quantitative parameters (except for right kidney transit time, liver uptake and
Tmax of both kidneys) showed good correlations for both agents.
Conclusion: The calculated ERPF with 99mTc-EC as compared to 99mTc-MAG3 is in closer proximity
to the true values. Also the use of 99mTc-EC compared to 99mTc-MAG3 in clinic due to simplicity of
preparation, higher stability, higher renal uptake, and lower hepatobiliary activity is better. Therefore
the use of 99mTc-EC as an appropriate substitute or ever preferred radiopharmaceutical for 99mTc-
MAG3 radiopharmaceutical for renal function studies is recommended.