[18F]FDG PET/CT imaging disproves renal allograft acute rejection in kidney transplant recipients with acute kidney dysfunction: a validation cohort

Abstract

Purpose. [ 18 F]FDG-PET/CT may predict the absence of acute allograft rejection (AR) in kidney transplant recipients (KTRs) with acute kidney injury (AKI). Still, the proposed threshold of 1.6 of the mean of mean standardized uptake values (mSUVmean) in the renal parenchyma needs validation.Methods. We prospectively performed 86 [ 18 F]FDG-PET/CT in 79 adult KTRs who underwent per cause transplant biopsy for suspected AR. Biopsy-proven polyoma-BK nephropathies (n=7) were excluded.PET/CT was performed 192 ± 18 minutes after administration of 254.4 ± 30.4 MBq of [ 18 F]FDG. The SUV mean was measured in both upper and lower poles of the renal allograft. One-way analysis of variance (ANOVA) and Tukey's studentized range test were sequentially performed. The receiver operating characteristic (ROC) curve was drawn to discriminate "AR" from non-pathological ("normal" + "borderline") conditions.Results. The median age of the cohort was 55 [43; 63] years, with M/F gender ratio of 47/39. The mean eGFR was 31.9 ± 14.6 ml/min/1.73m². Biopsies were categorized in 4 groups: "normal" (n=54), "borderline" (n=9), "AR" (n=14) or "others" (n=2). The median [min; max] mSUV mean reached 1.72 [1.02; 2.07], 1.97 [1.55; 2.11], 2.13 [1.65, 3.12] and 1.84 [1.57; 2.12] in "normal", "borderline", "AR" and "others" groups, respectively. ANOVA demonstrated a signi cant difference of mSUV mean among groups (F=13.25, p<0.0001). The ROC area under the curve was 0.86. Test sensitivity and speci city corresponding to the threshold value of 1.6 were 100% and 30%, respectively. Conclusion.[ 18 F]FDG -PET/CT may help noninvasively prevent inessential transplant biopsies in KTR with AKI.

The uptake of [18F]-fluorodeoxyglucose by the renal allograft correlates with the acute Banff scores of cortex inflammation but not with the 1-year graft outcomes

“…[ 18 F]FDG-PET/CT is routinely used for the characterization, staging, and follow-up of inflammatory processes of various origins ( 14 ). The usefulness of [ 18 F]FDG-PET/CT in the management of KTRs presenting with suspected AR has been demonstrated in both training and validation cohorts ( 9 , 10 ). In our first pilot study published in 2015, sensitivity and specificity of [ 18 F]-FDG PET/CT in diagnosing acute rejection were 100% and 50% respectively, with a meanSUV threshold of 1.6.…”

“…Signed informed consent was obtained from all patients. These cohorts have been previously described, as “training” ( 9 ) and “validation” ( 10 ) sets.…”

“…The PET/CT procedure was performed using cross-calibrated Philips GEMINI TF Big Bore or TF 16 PET/CT systems (Philips Medical Systems, Cleveland, OH, USA) at 194 ± 19 min after intravenous administration of a mean dose of 243 ± 35 MBq of 18 FDG before any modification of immunosuppressive regimens, as previously described ( 9 , 10 ). A low-dose helical CT (5-mm slice thickness, 120-kV tube voltage, and 40-mAs tube current-time product) centered on the renal transplant was performed, followed by a PET emission scanning with two-bed positions each lasting 4 min.…”

“…Imaging techniques have significantly improved over the past decades, thereby proposing another approach to the noninvasive diagnosis of AR. More specifically, 18 F-fluorodeoxyglucose [( 18 F)FDG] positron-emission tomography combined with computed tomography (PET/CT) as first-line examination with a high negative predictive value may help noninvasively prevent avoidable transplant biopsies in kidney transplant recipients (KTRs) with clinically suspected AR but no histological lesions ( 9 , 10 ). Indeed, the AR-associated immunological reaction against donor antigens induces the recruitment of mononuclear leukocytes into the renal transplant, which corresponds to the core of the Banff classification.…”

Significance of nuclear medicine methods for diagnosis and predicting the course of renal transplantation complications

“…Hyperfixation [ 18 F] F-FDG (fluorodeoxyglucose, labelled with 18 F) correlates with the intensity of leukocyte infiltration and the activity of the inflammatory process that occurs with AR in graft tissues. The negative predicative level of [ 18 F] FDG PET/CT when predicting rejection is 100 % [31], which allows the method to be routinely used to prevent uninformative biopsies [25,31].…”