PET C-11 acetate is also a perfusion tracer for kidney evaluation purposes

International audienceRationale: Renal positron emission tomography (PET) functional imaging allows non-invasive and dynamic measurements of functional and metabolic parameters. [O-15]H2O is used as a perfusion tracer, and [C-11]acetate as an oxidative metabolism in this purpose, requiring two injections to assess those fundamental parameters. Yet, in cardiac physiology study, the high first-pass myocardial extraction fraction of [C-11]acetate allowed to use its influx rate as a blood flow marker too. Since [C-11]acetate has been characterized by a 20-25% single pass renal extraction in dogs, it could be used as a potential tracer for renal perfusion. The aim of this study was to determine whether [C-11]acetate influx rate can be used as quantitative in vivo marker of kidney perfusion in human. Methods: In 10 healthy subjects, dynamic PET acquisitions were performed after [O-15]H2O and [C-11]acetate injections spaced by a 15-minute interval. As previously validated, with compartmental modeling of kinetics, renal perfusion and oxidative metabolism were estimated respectively with influx rate of [O-15]H2O and efflux rate of [C-11]acetate. Additionally, influx rate of [C-11]acetate was regressed to influx rate of [O-15]H2O. Results: Renal time activity curves of [C-11]-acetate was best fitted with a mono compartmental model compared to a bi-compartmental model (p \textless 0.0001). [C-11]acetate influx rate was significantly correlated with perfusion quantified with [O-15]H2O (r(2) = 0.37, p \textless 0.001) at baseline. This regression allowed the computation of a renal [C-11]acetate extraction fraction (EF), and further the computation of renal blood flow from its influx rate. Conclusion: In healthy subjects, over a wide range of renal perfusion, direct estimates of renal oxygen consumption as well as tissue perfusion can be obtained by PET with a single tracer [C-11]acetate. This approach needs to be validated in CKD patients, and would be of great interest to design clinical protocol aiming at evaluating ischemic nephropathies candidate to revascularization. (C) 2019 Elsevier Inc. All rights reserved