In vivo imaging of the spinal cord cholinergic system with PET

Purpose: Our goal was to demonstrate the feasibility of an in vivo noninvas ive method for imaging spinal cord cholinergic terminals using (+)-4-[F-18] fluorobenzyltrozamicol ([F-18]FBT) and PET. Method: In vitro and in vivo experiments in rats were conducted to demonstr ate the specific binding characteristics, localization, and time course of [H-3]FBT binding in the spinal cord. PET imaging was then performed on seve n rhesus monkeys. Results: The rat studies demonstrate high specific binding in the spinal co rd with a distribution coinciding with the known distribution of cholinergi c terminals. In vivo tracer concentrations in the spinal cord and basal gan glia were of the same magnitude. With use of [F-18]FBT and PET in the rhesu s monkey, the spinal cord was clearly visualized, with tracer concentration in the spinal cord being approximately one-fourth of that seen in the basa l ganglia. Conclusion: This work demonstrates the feasibility of imaging cholinergic t erminals in vivo in the spinal cord using [F-18]FBT and PET.