Glomerular Filtration Rate Evaluation in Patients with Urinary Stone using Tc-99m DTPA Quantitative Single-Photon Emission Computed Tomography/Computed Tomography

Objectives We aimed to evaluate glomerular filtration rate (GFR) in patients with urinary stone using quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) post Tc-99m DTPA injection.

Methods Seventy-one urinary stone patients (m:f=32:39, age=58.7±13.0y, unilateral:bilateral urinary stones=50:21) and 29 healthy donors for kidney transplantation (m:f=17:12, age=46.6±13.4y) underwent Tc-99m DTAP quantitative SPECT/CT from March 2015 to December 2015. Serum creatinine level and eGFR were also checked within 30 days before or after the SPECT/CT. Split GFR of the individual kidneys were calculated from the SPECT/CT derived %uptake of Tc-99m DTPA at 2~3min post injection [split GFR (mL/min)=%uptake × 10.165 + 17.7769].

Results The 71 urinary stone patients and the 29 kidney donors were not significantly different for gender proportion (p=0.3127) but the donors were significantly younger than the stone patients (p=0.0001). Total GFR from the SPECT/CT was significantly greater in the donor (129.29±17.66 mL/min) than the unilateral (115.85±25.04 mL/min) and the bilateral (110.92±25.99 mL/min) urinary stone patients (p=0.013, ANOVA). eGFR was also significantly higher in the donor (93.28±15.39 mL/min/1.73m2) than the unilateral (81.71±23.62 mL/min/1.73m2) and the bilateral (73.09±25.99 mL/min/1.73m2) urinary stone patients (p=0.006, ANOVA), but serum Cr level was not significantly different among the 3 groups (the donor=0.82±0.15 mg/dL, the unilateral=0.94±0.41 mg/dL and the bilateral=1.05±0.57 mg/dL) (p=0.121, ANOVA). Split GFR from the SPECT/CT was evaluated for 29 donor kidneys (arithmetic mean of the 2 kidneys), 50 naïve kidneys of unilateral urinary stone patients and 92 stone kidneys (76 renal stone, 13 ureter stone, and 3 renal/ureter stone). There was no significant difference of split GFR between donor kidneys (64.65±8.83 mL/min) and naïve kidneys (62.55±15.04 mL/min) but the stone kidneys had significantly lower split GFR (54.28±15.08 mL/min) than other kidneys (p<0.001, ANOVA). The stone kidneys having both renal and ureter stones (n=3) had lower slit GFR (49.56±15.07 mL/min) than those with ureter stone (n=13, split GFR 53.41±14.63 mL/min) and those with renal stone (n=76, split GFR 54.62±15.32 mL/min), although statistical significance was not reached (p=0.8132, Kruskal-Wallis test).

Conclusions Total and split GFR obtained from the Tc-99m DTPA quantitative SPECT/CT were useful for evaluation of renal function of urinary stone patients. Disease burden of urinary stone patients may be assessed using the quantitative SPECT/CT.