Reliability of rubidium-82 PET/CT for renal perfusion determination in healthy subjects

Abstract

Background Changes in renal perfusion may play a pathophysiological role in hypertension and kidney disease, however to date, no method for renal blood flow (RBF) determination in humans has been implemented in clinical practice. In a previous study, we demonstrated that estimation of renal perfusion based on a single positron emission tomography/computed tomography (PET/CT) scan with Rubidium-82 (82Rb) is feasible and found an approximate 5% intra-assay coefficient of variation for both kidneys, indicative of a precise method.This study’s aim was to determine the day-to day variation of 82Rb PET/CT and to test the method’s ability to detect increased RBF induced by infusion of amino acids. Methods Seventeen healthy subjects underwent three dynamic 82Rb PET/CT scans over two examination days comprising: Day A, a single 8-minute dynamic scan and Day B, two scans performed before (baseline) and after RBF stimulation by a 2-hour amino acid-infusion. The order of examination days was determined by randomization. Time activity curves for arterial and renal activity with a 1-tissue compartment model were used for flow estimation; the K1 kinetic parameter representing renal 82Rb clearance. Day-to-day variation was calculated based on the difference between the unstimulated K1 values on Day A and Day B and paired t-testing was performed to compare K1 values at baseline and after RBF stimulation on Day B. Results Day-to-day variation was observed to be 5.5% for the right kidney and 6.0% for the left kidney (n = 15 quality accepted scans). K1 values determined after amino acid-infusion were significantly higher than pre-infusion values (n = 17, p = 0.001). The mean percentage change in K1 from baseline was 13.2 ± 12.9% (range − 10.4 to 35.5) for the right kidney; 12.9 ± 13.2% (range − 15.7 to 35.3) for the left kidney. Conclusion Day-to-day variation is acceptably low. A significant K1 increase from baseline is detected after application of a known RBF stimulus, indicating that 82Rb PET/CT scanning can provide a precise method for evaluation of RBF and it is able to determine changes herein. Clinical Trial Registration EU Clinical Trials Register, 2017-005008-88. Registered 18/01/2018.

First-time rest-stress dynamic whole-body 82Rb-PET imaging using a long axial field-of-view PET/CT scanner

“…The splenic switch-off is known when using Regadenoson as stressor [ 7 ] and with whole-body imaging it can be used to identify inadequate vasodilatory response. Renal function may also be effectively evaluated, consistent with recent reports [ 8 ].…”

Renal and systemic hemodynamic effects of empagliflozin: Three randomized, double blind, placebo controlled cross-over trials

“…RBF RBF was estimated based on renal uptake of 82 Rb measured with 82 Rb-PET/CT scans. Scanning procedure and data analysis was performed as described by Langaa et al [19,20]. In short, a low dose CT scan was used for attenuation correction.…”

Dynamic rubidium‐82 PET/CT as a novel tool for quantifying hemodynamic differences in renal blood flow using a one‐tissue compartment model

“…Imaging has important benefits for determining renal perfusion compared to time-honored gold standard methods such as para-aminohippurate clearance; it is less invasive, faster and allows for regional comparison within the kidney and between the kidneys. [3][4][5][6] [ 15 O]H 2 O positron emission tomography/computed tomography (PET/CT) is a widely used technique to assess renal perfusion. 3 However, rubidium-82 ( 82 Rb) PET/CT might be an alternative technique, which is easy to implement as it does not require an on-site cyclotron.…”

“…5 Combining physiological stimuli with 82 Rb PET/CT offers unique opportunities to test the kidney under various conditions making dynamic 82 Rb PET/CT an interesting technique for dedicated renal stress testing. [6][7][8][9] One-tissue compartment models have been validated for myocardial blood flow quantification and are currently in routine clinical use. 10,11 Previous work by Tahari et al and Langaa et al demonstrated the feasibility of 82 Rb PET/CT with one-tissue compartment models for assessing renal perfusion.…”

“…From renal physiology studies it is known that kidney function increases after a stimulus such as an oral protein load or an intravenous infusion with amino acids, glucagon, or dopamine 5 . Combining physiological stimuli with 82 Rb PET/CT offers unique opportunities to test the kidney under various conditions making dynamic 82 Rb PET/CT an interesting technique for dedicated renal stress testing 6–9 …”