Improved measurement of the glomerular filtration rate from Tc-99m DTPA scintigraphy in patients following nephrectomy

Abstract

ObjectiveWe aimed to improve Tc-99m DTPA glomerular filtration rate (GFR) scintigraphy (Gates’ method) in a prospective study using Cr-51 EDTA GFR test as a gold standard.MethodsFifty-seven Tc-99m DTPA GFR scintigrams in 45 subjects (male/female = 33:12, age = 45.9 ± 17.6 years, 14 healthy volunteers and 31 nephrectomised patients) were compared using Cr-51 EDTA GFR tests. Using the %renal uptake of Tc-99m DTPA and Cr-51 EDTA GFR, a revised equation for GFR was established through linear regression analysis.ResultsThe revised equation for improved GFR was GFR(mL/min) = (%renal uptake × 11.7773) − 0.7354. Gates’ original GFRs (70.1 ± 20.5 mL/min/1.73 m2) were significantly lower than Cr-51 EDTA GFRs (97.0 ± 31.9 mL/min/1.73 m2; P < 0.0001), but the improved GFRs (98.0 ± 26.3 mL/min/1.73 m2) were not different from (P = 0.7360) and had a significant correlation with (r = 0.73, P < 0.0001) the Cr-51 EDTA GFRs. The revised GFR equation effectively demonstrated perioperative GFR changes in kidneys that were operated on and the contralateral kidneys at 3 and 6 months post-partial nephrectomy (n = 25).ConclusionsGFR measurement using Tc-99m DTPA scintigraphy could be significantly improved by a revised equation derived from the comparison with Cr-51 EDTA GFR.Key Points• Measurement of glomerular filtration rate is difficult following nephrectomy.• Measurements can be significantly improved by new renal sctintigraphic methods.• This helps physicians to measure kidney function of patients following nephrectomy.• Management of renal tumour patients should become more effective.