Relative 99mTc-MAG3 renal uptake: reproducibility and accuracy

Area of Science:

• Nuclear Medicine
• Radiopharmacology
• Renal Imaging

Background:

• Accurate assessment of relative renal function is crucial in diagnosing and managing various kidney conditions.
• Technetium-99m mercaptoacetyltriglycine (99mTc-MAG3) scintigraphy is a widely used functional renal imaging technique.
• Estimating the relative percentage uptake of 99mTc-MAG3 requires robust and validated methodologies.

Purpose of the Study:

• To evaluate the reproducibility and accuracy of different methods for quantifying 99mTc-MAG3 relative percentage uptake.
• To compare various uptake algorithms and background correction techniques for 99mTc-MAG3 renography.
• To identify the optimal method for reliable estimation of left-to-right renal uptake ratio using 99mTc-MAG3.

Main Methods:

• Reproducibility assessed in healthy volunteers undergoing two 99mTc-MAG3 renographic studies with varied algorithms, background corrections, and time intervals.
• Accuracy evaluated in patients with known relative renal function by comparing 99mTc-MAG3 uptake with 99mTc-dimercaptosuccinic acid (DMSA) uptake as a reference.
• Analysis included the integral method (with and without background correction) and the slope method, alongside the Patlak-Rutland plot.

Main Results:

• The integral method combined with subrenal or perirenal background correction demonstrated superior reproducibility and accuracy.
• The Patlak-Rutland plot also showed good performance in estimating the 99mTc-MAG3 left-to-right uptake ratio.
• The integral method without background correction introduced systematic bias, and the slope method exhibited high variability.

Conclusions:

• The integral method with appropriate background correction (subrenal or perirenal) and the Patlak-Rutland plot are recommended for accurate 99mTc-MAG3 uptake ratio quantification.
• Methods lacking background correction or employing the slope method are not advised due to introduced bias and high variability, respectively.
• Optimized quantitative analysis of 99mTc-MAG3 renography enhances diagnostic reliability in assessing relative renal function.