Tc-99m-Mercaptoacetyltriglycine and Tc-99m-Dimercaptosuccinic Acid Scintigraphies for the Evaluation of Renal Parenchymal Lesions in Infants

Objective: Scintigraphy with Tc-99m dimercaptosuccinic acid (DMSA) is considered a reference method for the assessment of renal parenchymal lesions and estimation of differential renal function (DRF). Compared with Tc-99m mercaptoacetyltriglycin (MAG3), the disadvantages of DMSA are relatively higher radiation exposure to the kidney and longer procedural time. The aim of this study was to evaluate the performance of Tc-99m MAG3 dynamic renal scintigraphy in the detection of renal parenchymal defects and in the estimation of DRF in comparison with Tc-99m DMSA scintigraphy. Material and Methods: A retrospective review of the records indicated that 29 infants (20 boys and 9 girls) aged less than I year underwent both DMSA and MAG3 scintigraphies. The parenchymal phases of MAG3 scintigraphy were compared to DMSA images. Differential function was calculated based on the MAG3 and DMSA methods and the results were compared. Results: The findings of the two methods corresponded completely in 90% of patients. There was no significant difference between calculated DRF from DMSA and MAG3 images. There was a high correlation between the DRF obtained using the two methods (r = 0.91 and r = 0.90 for the left and right kidney, p < 0.01). The sensitivity and specificity of the MAG3 cortical images were calculated as 92% and 78%. Conclusion: We suggest that either a MAG3 or a DMSA scan can be used for the calculation of DRF. However, because of the low specificity of MAG3 cortical analysis, DMSA scintigraphy is required for the definitive diagnosis and management of renal cortical lesions.