Relative Tc-99m-MAG3 renal uptake: Reproducibility and accuracy

The aim of this study was to estimate the reproducibility and accuracy of T c-99m-mercaptoacetyltriglycine (MAG3) relative percentage uptake. Methods: Reproducibility was evaluated on healthy volunteers who were submitted twic e to a Tc-99m-MAG3 renographic study, which used different uptake algorithm s, different background corrections and different time intervals. Accuracy was evaluated in, a-group of patients with symmetrical or asymmetrical rela tive renal function, who underwent both Tc-99m-dimercaptosuccinic acid (DMS A) and Tc-99m-MAG3 studies, using the DMSA relative percentage uptake as a reference.; Results and Conclusion: The methods that combined the best repr oducibility and accuracy for estimating Tc-99m-MAG3 left-to-right uptake ra tio were the integral method, with subrenal or perirenal background correct ion, and the Patlak-Rutland plot. The use of the integral method without ba ckground correction introduced a systematic bias, whereas the slope method resulted in high variability. Therefore these methods cannot be recommended .