AbstractPurpose of the Report
18F-FDG PET/CT has been recently proposed as a noninvasive tool for the diagnosis of renal allograft acute rejection (AR) in kidney transplant recipients (KTRs). Still, the influence of kidney function on 18F-FDG uptake by renal grafts remains unknown.Patients and Methods
We retrospectively identified all KTRs who underwent at least one 18F-FDG PET/CT. Kidney transplant recipients with documented pyelonephritis or AR were excluded. Estimated glomerular filtration rate (eGFR) was assessed using chronic kidney disease (CKD)–EPI equation. Mean standardized uptake values (SUVmean) of renal graft cortex and aorta were measured in 4 and 1 volumes of interest, respectively. Spearman rank correlation coefficient (ρ) and analysis of variance (ANOVA) were performed.Results
Eighty-two KTRs underwent 18F-FDG PET/CT for tumor staging (n = 46), suspected infection (n = 11), or fever of unknown origin (n = 25). Mean eGFR was 50 ± 19 mL/min per 1.73 m2, including CKD stage 1 (n = 3), stage 2 (n = 21), stage 3a (n = 20), stage 3b (n = 29), and stage 4 (n = 9). Mean kidney and aorta SUVmean were 1.8 ± 0.2 and 1.7 ± 0.3, respectively. No significant correlation was observed between eGFR and kidney SUVmean (ρ, 0.119; P, 0.28) or aorta SUVmean (ρ, −0.144; P, 0.20). ANOVA showed no difference of kidney (P, 0.62) and aorta (P, 0.85) SUVmean between CKD groups. Mean coefficient of variation (on the basis of kidney SUVmean of >3 consecutive 18F-FDG PET/CT in 15 patients with no significant change of eGFR) reached 13.1%.Conclusions
The uptake of 18F-FDG by renal allografts within an hour postinjection is not significantly impacted by CKD.