P1‐388: Imaging of cholinergic terminals in the non‐human primate brain using 18F‐FEOBV PET: Development of a tool to assess cholinergic losses in Alzheimer's disease

First-in-human imaging and kinetic analysis of vesicular acetylcholine transporter density in the heart using [18F]FEOBV PET

In contrast to cardiac sympathetic activity which can be assessed with established PET tracers, there are currently no suitable radioligands to measure cardiac parasympathetic (cholinergic) activity. A radioligand able to measure cardiac cholinergic activity would be an invaluable clinical and research tool since cholinergic dysfunction has been associated with a wide array of pathologies (e.g., chronic heart failure, myocardial infarction, arrythmias). [18F]Fluoroethoxybenzovesamicol (FEOBV) is a cholinergic radiotracer that has been extensively validated in the brain. Whether FEOBV PET can be used to assess cholinergic activity in the heart is not known. Hence, this study aimed to evaluate the properties of FEOBV for cardiac PET imaging and cholinergic activity mapping. PET data were collected for 40 minutes after injection of 230 ± 50 MBq of FEOBV in four healthy participants (1 female; Age: 37 ± 10; BMI: 25 ± 2). Dynamic LV time activity curves were fitted with Logan graphical, 1-tissue compartment, and 2-tissue compartment models, yielding similar distribution volume estimates for each participant. Our initial data show that FEOBV PET has favorable tracer kinetics for quantification of cholinergic activity and is a promising new method for assessing parasympathetic function in the heart.

Quantification of brain cholinergic denervation in Alzheimer's disease using PET imaging with [18F]-FEOBV

¹⁸F-fluoroethoxybenzovesamicol (FEOBV) is a new PET radiotracer that binds to the vesicular acetylcholine transporter. In both animals and healthy humans, FEOBV was found sensitive and reliable to characterize presynaptic cholinergic nerve terminals in the brain. It has been used here for we believe the first time in patients with Alzheimer's disease (AD) to quantify brain cholinergic losses. The sample included 12 participants evenly divided in healthy subjects and patients with AD, all assessed with the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) cognitive scales. Every participant underwent three consecutive PET imaging sessions with (1) the FEOBV as a tracer of the cholinergic terminals, (2) the ¹⁸F-NAV4694 (NAV) as an amyloid-beta tracer, and (3) the ¹⁸F-Fluorodeoxyglucose (FDG) as a brain metabolism agent. Standardized uptake value ratios (SUVRs) were computed for each tracer, and compared between the two groups using voxel wise t-tests. Correlations were also computed between each tracer and the cognitive scales, as well as between FEOBV and the two other radiotracers. Results showed major reductions of FEOBV uptake in multiple cortical areas that were evident in each AD subject, and in the AD group as a whole when compared to the control group. FDG and NAV were also able to distinguish the two groups, but with lower sensitivity than FEOBV. FEOBV uptake values were positively correlated with FDG in numerous cortical areas, and negatively correlated with NAV in some restricted areas. The MMSE and MoCA cognitive scales were found to correlate significantly with FEOBV and with FDG, but not with NAV. We concluded that PET imaging with FEOBV is more sensitive than either FDG or NAV to distinguish AD patients from control subjects, and may be useful to quantify disease severity. FEOBV can be used to assess cholinergic degeneration in human, and may represent an excellent biomarker for AD.