A 7% Decrease in the Differential Renal Uptake of MAG3 Implies a Loss in Renal Function

• Type of Material: Article
• Authors: Andrew T Taylor Jr., Emory University; Amita Manatunga, Emory University; Raghuveer Halkar, Emory University; Muta M Issa, Emory University; Neeta V. Shenvi, Emory University
• Language: English
• Date: 2010-12
• Publisher: Elsevier: 12 months
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2010 Published by Elsevier Inc.
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.urology.2010.03.066
• Title of Journal or Parent Work: Urology
• ISSN: 0090-4295
• Volume: 76
• Issue: 6
• Start Page: 1512
• End Page: 1516
• Grant/Funding Information: This work was partially supported by a grant from the National Institute of Biomedical Imaging and Bioengineering, NIBIB, and the National Institute of Diabetes and Digestive and Kidney Diseases, NIDDK, R01-EB008838 and by a grant from Mallinckrodt, Inc.
• Research Categories: Biology, Biostatistics; Health Sciences, Radiology

Abstract

OBJECTIVES To address the fact that a decrease in the relative renal uptake of 99mTc-mercaptoacetyltriglycine (MAG3) on serial MAG3 scans may indicate a loss of function and require a change in management by providing guidance as to what constitutes a meaningful change in serial relative function measurements as well determining the normal variation of other common MAG3 renogram parameters. METHODS A prospective study was conducted in 24 male urology patients with stable renal function. The mean age was 66.5 ± 7.9 (SD) years; the mean serum creatinine was 1.38 ± 0.57 (SD) mg/dL, and the MAG3 renal scans were performed a mean of 11 ± 8 days apart. Each MAG3 scan included a measurement of relative function as well as the time to maximum counts and 20 minutes to maximum count ratios for both cortical and whole kidney regions of interest. RESULTS The Pearson and intraclass correlations for the baseline and repeat measurements of relative renal function were both 0.98. Bland-Altman plots showed no bias between the baseline and repeat relative uptake measurements. The mean difference between 2 repeated measurements of the relative MAG3 uptake was 0.04 ± 2.88% (SD) for the left kidney and 0.08 ± 3.07% (SD) for the right kidney. Comparable results were obtained for the other renogram parameters. CONCLUSIONS Measurements of relative renal uptake of MAG3 and common renogram parameters are highly reproducible; a decrease in relative uptake ≥7% (ie, 50%-43%) implies a loss in renal function.