Assessment of renal perfusion with 82-rubidium PET in patients with normal and abnormal renal function.

Background: Noninvasive measurement of renal blood flow (RBF) and renal vascular resistance (RVR) is challenging, yet critical in renal pathologies. This study evaluates the correlation between serum renal function markers and RBF/RVR assessed using rubidium PET.

Methods: Dynamic images from 53 patients who underwent rubidium PET for nonrenal indications were analyzed. RBF was determined using a one-compartment model, and RVR was calculated by dividing mean arterial pressure by RBF.

Results: The study included 51 patients (31 females and 20 males). Among them, 35 had normal renal function [estimated glomerular filtration rate (eGFR) ≥60 ml/min/1.73 m 2 ], and 16 had abnormal renal function (eGFR <60 ml/min/1.73 m 2 ). Patients with normal renal function had significantly higher RBF [median (interquartile range): 443 (297-722) vs 173 (108-380) ml/min/100 g, P  = 0.022] and lower RVR [19.1 (12.4-27.2) vs 49.6 (24.4-85.7) mmHg×min×g/ml, P  = 0.0011) compared with those with abnormal renal function. There was a moderate correlation between RBF and eGFR ( r  = 0.62, P  < 0.0001) and between RVR and eGFR ( r  = -0.59, P  < 0.0001) in both groups. Among patients with normal renal function, RBF was negatively correlated with age ( r  = -0.51, P  = 0.0017) but there was no correlation among patients with abnormal renal function ( r  = 0.21, P  = 0.44).

Conclusion: PET-measured RBF and RVR correlate with renal function markers and differ significantly by renal function status. Further studies are needed to validate rubidium PET's precision and clinical applicability.