Analyze the Effects of Different Anesthesia on Brain Uptake of ¹⁸F-FDG in Mice Using Dynamic Micro PET/CT

Purpose: To evaluate the effect of different concentrations of chloral hydrate and isoflurane anesthesia on brain uptake of ¹⁸F-FDG in mice.

Methods: Total 30 clean mice aged 3-4 weeks fasted for 12±4 hours first, and were randomly divided into 10 groups for the built of concentration gradient of anesthesia, we set different concentration for two drug groups: chloral hydrate group: 25 mg/kg, 50 mg/kg, 100 mg/kg, 150 mg/kg, 200 mg/kg; isoflurane anesthesia group: 1.5%, 2%, 3%, 4%, and 5% (maintenance dose of anesthesia was 1.5%). Finally, twelve mice come from four groups of light (50mg/kg chloral hydrate group and 2% isoflurane group) and deep (100mg/kg chloral hydrate group and 4% isoflurane group) anesthetic status were included for further study. Anesthetized mice were fixed in the scanning bed, and injected with ¹⁸F-FDG via tail vein, and the 60-minute PET/CT dynamic images were obtained after the injection of tracer. PMOD software were used for the reconstruction and analysis of the images. During anesthesia, the status indexes included anesthesia induction time, maintenance time and waking time, respiration, body temperature, pain response, corneal reflex and limb movement state were recorded.

Results: Mean SUVmax value were calculated for brain images of three mice in each group. Lower SUVmax value were found in the mice with the deeper anesthesia, no matter the kind of anesthesia method. The FDG uptake peak after the injection of anesthesia occurred in 35-45 minutes, while inhalation anesthesia occurred in 25-35 minutes. Compared with isoflurane inhalation anesthesia, chloral hydrate has longer average induction time, recovery time and lower body temperature. The symptoms of different degrees of opisthotonos were observed in some mice of chloral hydrate group.

Conclusions: The FDG uptake was affected by the depth of anesthesia, compared with chloral hydrate, isoflurane is more stable in anesthesia effect, easier on control of anesthesia depth, and has less harms on experimental animals. Key words: Micro PET/CT; Anesthesia; SUVmax; Isoflurane; Chloral hydrate

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