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
.