TITLE:
Effect of the Energy Window Width on the Estimation of Renal Function from Dynamic Renal Scintigraphy with 99mTc-MAG3
AUTHORS:
Yuji Asano, Yusuke Ohzeki, Yusuke Inoue
KEYWORDS:
99mTc-Mercaptoacetyltriglycine (MAG3), Dynamic Renal Scintigraphy, Renal Function, Energy Window, Quantitative Measurement
JOURNAL NAME:
Open Journal of Medical Imaging,
Vol.5 No.2,
May
15,
2015
ABSTRACT: Objective: The width of the photopeak energy window influences the image quality and quantitative accuracy of gamma camera imaging. We compared 20% and 15% energy windows in renal scintigraphy with 99mTc-mercaptoacetyltriglycine (MAG3), especially in terms of camera-based quantitative estimation of renal function. Materials and Methods: Forty patients who underwent dynamic renal scintigraphy with 99mTc-MAG3 were enrolled in this study. Images were acquired simultaneously using two energy windows centered at 140 keV and with widths of 20% and 15%. Fractional renal uptake was calculated as the ratio of initial renal uptake estimated by patient imaging to injected dose estimated by syringe imaging, and was converted to MAG3 clearance using an empirical equation determined previously from data obtained with a 20% energy window. Relative function of the right kidney was also assessed. Visual evaluation was performed to compare image quality between the 20% and 15% energy windows. Results: Both total kidney MAG3 clearance and relative function of the right kidney were identical between the 20% and 15% energy windows. Image quality was also similar irrespective of the energy window width. Conclusions: The camera-based method established using a 20% energy window is applicable for the estimation of renal function using a 15% energy window, and data obtained using 20% and 15% windows are interchangeable.