FEOBV-PET to quantify cortical cholinergic denervation in AD: Relationship to basal forebrain volumetry

Background and purpose: Fluorine-18-fluoroethoxybenzovesamicol([¹⁸ F]-FEOBV) is a PET radiotracer previously used in neurodegenerative diseases to quantify brain cholinergic denervation. The current exploratory study aimed at verifying the reliability of such an approach in Alzheimer's disease (AD) by demonstrating its concordance with MRI volumetry of the cholinergic basal forebrain (ChBF).

Methods: The sample included 12 participants evenly divided between healthy volunteers and patients with AD. All participants underwent MRI ChBF volumetry and PET imaging with [¹⁸ F]-FEOBV. Comparisons were made between the two groups, and partial correlations were performed in the AD patients between [¹⁸ F]-FEOBV uptake in specific cortical regions of interest (ROIs) and volumetry of the corresponding ChBF subareas, which include the nucleus basalis of Meynert (Ch4), and the medial septum/vertical limb of the diagonal band of Broca (Ch1/2).

Results: Patients with AD showed both lower ChBF-Ch4 volumetric values and lower [¹⁸ F]-FEOBV cortical uptake than healthy volunteers. Volumes of the Ch4 subdivision were significantly correlated with the [¹⁸ F]-FEOBV uptake values observed in the relevant ROIs. Volumes of the Ch1/2, which remains relatively unaffected in AD, did not correlate with [¹⁸ F]-FEOBV uptake in the hippocampus, nor in any cortical area.

Conclusion: These results suggest that cortical cholinergic denervation as measured with [¹⁸ F]-FEOBV PET is proportional to ChBF atrophy measured by MRI-based volumetry, further supporting the reliability and validity of [¹⁸ F]-FEOBV PET to quantify cholinergic degeneration in AD.