Al18F-NODA-butyric acid: Biological evaluation of a new PET renal radiotracer

Abstract

Introduction Renal scintigraphy is an important imaging modality for the diagnosis and management of a variety of renal diseases including obstruction and renovascular hypertension as well as the evaluation of absolute and relative kidney function. The goal of this work was to evaluate Al18F-NODA-butyric acid (Al18F-1) as a potential PET tracer to image the kidneys and monitor renal function by comparing its pharmacokinetic properties with those of 131I-o-iodohippurate (131I-OIH), the radioactive standard for the measurement of effective renal plasma flow. Methods Al18F-1 was prepared in aqueous conditions using a one-pot Al18F-radiofluorination method and its radiochemical purity was determined by HPLC. Biodistribution studies, using 131I-OIH as an internal control, were performed in normal rats and in rats with renal pedicle ligation. In vitro stability and metabolism of Al18F-1 were analyzed by HPLC. Dynamic microPET/CT studies were conducted in normal rats. Results Al18F-1 showed excellent stability in vitro and in vivo. Biodistribution studies in normal rats and in rats with simulated renal failure confirmed that Al18F-1 was exclusively cleared through the renal-urinary pathway and that the hepatic/gastrointestinal activity was less for Al18F-1 than for 131I-OIH both at 10 and 60 min. Dynamic PET showed a rapid transit of Al18F-1 through the kidneys into the bladder. Conclusion These results suggest that the easily labeled Al18F-based compounds provide a highly promising approach for the development of a PET renal radiotracer that combines superior imaging qualities with a reliable measure of effective renal plasma flow.

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