Longitudinal assessment of renal allograft function in donors and pediatric recipients by arterial spin labeling MRI...

We analyzed cortical renal blood flow (cRBF) by ASL-MRI in ten donors (4 females, mean age 46 ± 6) and dedicated pediatric recipients (4 females, mean age 14 ± 4) before transplantation and at 3-, 6-, and 12-months post-transplant to identify allograft functional adaptation. Baseline values were compared to post-transplant values and correlated with estimated glomerular filtration rate (eGFR). Additionally, renal plasma flow (RPF) and estimated filtration fraction (eFF) were calculated. Both cRBF and eGFR demonstrated a highly significant increase at 3 months compared to baseline (mean cRBF 251.71 ± 78.27 vs. 486.61 ± 156.08 ml/kidney/min, p = 0.0001; mean eGFR 46.62 ± 16.36 vs. 69.81 ± 24.83 ml/min/1.73 m²; p = 0.02) and remained consistent until the end of the observed period. Patients with impaired function and lower eGFR at 3 months exhibited a smaller increase in cRBF compared to the rest of the group (p = 0.01). eFF did not change significantly throughout the observed period (p = 0.07, p = 0.07, and p = 0.68, respectively), suggesting absence of hyperfiltration. cRBF may serve as a significant renal biomarker for longitudinal follow-up of renal allografts, enabling tracking of perfusion adaptation and identification of critical timepoints for clinical intervention.