Comparison of glomerular filtration rate calculated by Gamma camera-based Gates method with various estimated glomerular filtration rate methods

Glomerular filtration rate (GFR) is the best parameter to assess functional status of kidneys. Various equations have been devised to estimate the GFR indirectly using different patient indices. Among nuclear medicine methods, plasma sampling method is the most accurate for estimation of GFR; however, Gamma camera-based method using ^99mTc-DTPA is used widely as it is noninvasive and easily available. Recently, the estimated GFR (eGFR) methods are gaining worldwide acceptance for quick estimation of GFR using serum creatinine and patient indices. The aim of this study was to compare Gamma camera-based Gates method with eGFR methods (Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Modification of Diet in Renal Disease (MDRD), Cockcroft Gault (CG)) of GFR estimation. In all patients, CKD-EPI best correlated with Gates method (r = 0.826, P < 0.001). However, at GFR <30 and >61 ml/min, CKD-EPI best correlated with Gates method (r = 0.62, P = 0.003 and r = 0.42, P = 0.004, respectively) while at GFR of 31–60 ml/min CG equation best correlated with Gates method (r = 0.52, P = 0.015). Hence, CKD-EPI best correlates with GFR calculated with Gates method overall and at <30 and >60 ml/min in this study