Clinically Silent Renal Asymmetry: Marked Disparity on Tc-99m DTPA Scintigraphy

A reliable, non-invasive method for quantitatively evaluating each person's kidney function is Tc-99m diethylenetriamine pentaacetate (DTPA) dynamic renal scintigraphy. Split renal perfusion, uptake, time-to-peak activity, and glomerular filtration rate (GFR) were assessed in 33 consecutive patients (January 2015–July 2024) who received medical treatment for suspected or confirmed renal failure. Kidney stones (n = 14), urinary tract infections (n = 5), acute kidney injury (n = 2), renal transplantation (n = 1), and obstructive uropathy (n = 1) were associated with the underlying conditions. The validated Gates method was used to calculate GFR in accordance with standardized European Association of Nuclear Medicine (EANM) protocols. Individual kidney parameters were correlated with clinical variables and compared using paired t-tests. The average GFR was 65.4 ± 24.1 mL/min. Significant inter-kidney asymmetry was frequently observed in the 32 patients with two functioning kidneys: in 56% of cases, one kidney contributed ≥ 70% of total function, and in 28% of cases, ≥ 80%. In 72% of patients, there was additionally a difference of more than 20% between perfusion and uptake. Lower total GFR was substantially correlated with older age and comorbidities. Clinically silent, but significant functional differences between the kidneys that are not visible from serum creatinine or estimated GFR alone can be reliably detected by Tc-99m DTPA scintigraphy. These results support the use of quantitative renal scintigraphy for more accurate diagnosis, risk assessment, and tailored treatment of patients with renal disease. They also emphasize the significance of regular split-function reporting in nuclear medicine practice.