Correlations and Differences in Glomerular Filtration Rates Calculated Through In-House and Non-In-House Workstations of Scintigraphic Gamma Cameras

Background: Technetium-99m diethylene triaminepentaacetic acid (Tc-99m DTPA) renal scintigraphy using modified Gate’s method is commonly adopted to calculate glomerular filtration rate (GFR). Objectives: The purpose of this study was to find the correlations between GFRs, which are calculated by the in-house and non-in-house workstations from gamma cameras (GC) manufactured by different firms. Patients and Methods: Medical records of patients receiving Tc-99m DTPA renal scan between January and December 2016 were analyzed. Patients were allocated randomly to a GC (1 or 2). The calculated GFRs were conducted by the in-house workstation (group A: workstation 1/ GC 1; group B: workstation2/ GC 2) and the non-in-house workstation from the GC (group C: workstation 2/ GC 1; group D: workstation 1/ GC 2). All patients had their creatinine levels checked to calculate the estimated GRF (eGFR) as the reference data. Comparison of correlation and difference between GFR calculations (group A, B, C and D), eGFRs and clinical parameters was analyzed. Results: Forty patients (24 men, 16 women) were enrolled in this study. The average of eGFRs was 63.0 ± 38.5 mL/min/1.73m2. The GFRs (group A to D) calculated were all significantly correlated with the eGFR. However, there was a significant difference between group C and eGFR (P = 0.0021), and group D and eGFR (P = 0.0262). Eight patients (20%) had changed stage of chronic kidney disease when using non-in-house workstations, compared to in-house workstations from GC. Conclusion: GFRs calculated by the non-in-house workstation were significantly different from eGFR. Use of workstation and GC from the same manufacturer would provide more accurate data in the clinical setting.