In Vivo Evaluation of Brain [¹⁸F]F-FDG Uptake Pattern Under Different Anaesthesia Protocols

Background/aim: Since the use of anaesthetics has the drawback of altering radiotracer distribution, preclinical positron emission tomography (PET) imaging findings of anaesthetised animals must be carefully handled. This study aimed at assessing the cerebral [¹⁸F]F-FDG uptake pattern in healthy Wistar rats under four different anaesthesia protocols using microPET/magnetic resonance imaging (MRI) examinations.

Materials and methods: Post-injection of 15±1.2 MBq of [¹⁸F]F-FDG, either while awake or during the isoflurane-induced incubation phase was applied. Prior to microPET/MRI imaging, one group of the rats was subjected to forane-only anaesthesia while the other group was anaesthetised with the co-administration of forane and dexmedetomidine/Dexdor^® Results: While as for the whole brain it was the addition of dexmedetomidine/Dexdor^® to the anaesthesia protocol that generated the differences between the radiotracer concentrations of the investigated groups, regarding the cortex, the [¹⁸F]F-FDG accumulation was rather affected by the way of incubation. To ensure the most consistent and highest uptake, forane-induced anaesthesia coupled with an awake uptake condition seemed to be most suitable method of anaesthetisation for cerebral metabolic assessment. Diminished whole brain and cortical tracer accumulation detected upon dexmedetomidine/Dexdor^® administration highlights the significance of the mechanism of action of different anaesthetics on radiotracer pharmacokinetics.

Conclusion: Overall, the standardization of PET protocols is of utmost importance to avoid the confounding factors derived from anaesthesia.