99mTc-DTPA Renal Dynamic Imaging Method May Be Unsuitable To Be Used as the Reference Method in Investigating the Validity of CDK-EPI Equation for Determining Glomerular Filtration Rate

Abstract

ObjectiveTo compare the measurements of glomerular filtration rate (GFR) determined by 99mTc-diethylene triamine pentaacetic acid (99mTc-DTPA) renal dynamic imaging with those estimated by Chronic Kidney Disease Epidemiology Collaboration (CDK-EPI) equation and to identify a more accurate measurement of GFR of chronic kidney disease (CKD) patients in clinical practice.MethodsThe GFR was determined simultaneously by 3 methods: (a) dual plasma sample clearance method (tGFR); (b) renal dynamic imaging method (dGFR); (c) CDK-EPI equation (eGFR). The tGFR was employed as the reference method. The correlation, regression, and limit of agreement of dGFR and eGFR were used to demonstrate the validity of the two methods. The comparison of bias, precision, and accuracy between dGFR and eGFR was analyzed to identify the most suitable method. The analysis of bias, precision and accuracy was repeated after stratifying patients by a measured tGFR cutpoint of 60 ml·min−1·(1.73 m2)−1.ResultsA total of 149 patients were enrolled. Both dGFR and eGFR correlated well with tGFR and the regression equation of dGFR and eGFR against tGFR was respectively Y = −4.289+0.962X (r = 0.919; RMSE = 14.323 ml.min−1. (1.73 m2)−1; P<0.001) and Y = 2.462+0.914X (r = 0.909; RMSE = 15.123 ml.min−1. (1.73 m2)−1; P<0.001). In addition, Bland-Altman analysis showed preferable agreement between the two methods and the reference method. The comparison revealed that eGFR, compared with dGFR, showed better performance on bias and 50% accuracy and similar performance on other indexes in the whole cohort and the lower-GFR subgroup, whereas in the higher-GFR subgroup the difference of the two methods was not significant in all parameters.ConclusionsAlthough both CDK-EPI equation and renal dynamic imaging can be used to determine the GFR of CKD patients, CDK-EPI equation is more accurate than renal dynamic imaging. As a result, 99mTc-DTPA renal dynamic imaging may be unsuitable to be used as the reference method in investigating the validity of CDK-EPI equation.

Is the Chronic Kidney Disease Epidemiology Collaboration creatinine&ndash;cystatin C equation useful for glomerular filtration rate estimation in the elderly?

“…After image acquisition, blood samples were taken 2 and 4 hours after injection from the opposite forearm. The plasma was separated, and radioactivity was counted in a multi-function well counter (ZD-6000 multi-function instrument; Zhida Technology Company, Xian, People’s Republic of China) 12. The 99m Tc-DTPA renal dynamic imaging GFR measured in our study can be calibrated to dual plasma samples 99m Tc-DTPA clearance GFR using a linear regression equation:…”

Estimation of glomerular filtration rate by a radial basis function neural network in patients with type-2 diabetes mellitus

“…Third, a previous study-indicated that GFR estimated by 99mTc-DTPA dynamic renal imaging might not better than the modified abbreviated MDRD equation [31], and the renal dynamic imaging method was less accurate than CKD-EPI equation as well [32]. However, the same study found that the two methods performed similar capability in determining GFR among higher-GFR patients [32], and 99m Tc-DTPA dynamic renal dynamic imaging yields accurate results that are nearly the same as those from measurements of inulin clearance [33]. Rehling et al showed that a regression line between the values measured by these different methods did not differ from the line of identity [33].…”

Glomerular filtration rate measured by 99mTc‐DTPA renal dynamic imaging is significantly lower than that estimated by the CKD‐EPI equation in horseshoe kidney patients

“…Accurate assessment of GFR is essential for interpreting symptoms and signs and for drug dosing, detecting and managing kidney disease and assessing prognosis . Inulin clearance is the gold standard for GFR determination, but it cannot be applied widely in clinical practice because of the technical complexity and time‐consuming nature of the procedure . Therefore, several equations, such as the Chronic Kidney Disease Epidemiology Collaboration (CKD‐EPI) equation and Modification of Diet in Renal Disease (MDRD) equation had been developed to estimate GFR .…”

“…They are non‐invasive, simple, and relatively accurate. Furthermore, renal dynamic imaging, also named Gate's method, is another method for measuring GFR due to the following advantages: achievement of unilateral renal blood flow and kidney function; the entire procedure is performed in approximately 20 min; no blood or urine collection is needed; and its result is not affected by the diet of the patient . However, it is unclear whether the isotope renal dynamic imaging can accurately assess renal function in HSK patients with renal fusion anomalies.…”

“… 99m Tc‐DTPA renal dynamic imaging method (Gate's method) Gate developed a simple method to determine GFR in 1982 named the Gate's method, and it was modified in 1983 . It is also called the renal dynamic imaging method because GFR can be calculated simultaneously using a computer system when the patient is undergoing renal dynamic imaging.…”