MULTICENTER TRIAL VALIDATION OF A CAMERA-BASED METHOD TO MEASURE TC-99M MERCAPTOACETYLTRIGLYCINE, OR TC-99M MAG(3), CLEARANCE

PURPOSE: To evaluate an improved camera-based method for calculating t he clearance of technetium-99m mercaptoacetyltriglycine (MAG(3)) in a multicenter trial, MATERIALS AND METHODS: Tc99m MAG(3) scintigraphy wa s performed in 49 patients at three sites in the United States and Can ada. The percentage of the injected dose of Tc-99m MAG(3) in the kidne y at 1-2, 1.0-2.5, and 2-3 minutes after injection was correlated with the plasma-based Tc-99m MAG(3) clearances. The data were combined wit h the results obtained in 20 additional patients in a previously publi shed pilot study. RESULTS: Regression models correlating the plasma-ba sed Tc-99m MAG(3) clearance with the percentage uptake in the kidney f or each time interval were developed; there was no statistically signi ficant difference among sites in the regression equations. Correction for body surface area statistically significantly (P < .005) improved the correlation coefficient for each time interval. For the 1.0-2.5-mi nute interval, the body surface area-corrected correlation coefficient for the four combined sites was .87, and it improved to .93 when one outlier was omitted from the analysis. Similar results were obtained w ith the other time intervals. Independent processing by two observers showed no clinically important differences in the percentage dose in t he kidney or in relative function. CONCLUSION: An improved camera-base d method to calculate the clearance of Tc-99m MAG(3) was validated in a multicenter trial.