Micro-autoradiographic method to study [18F]FDG uptake in mouse tissue.

A new micro-autoradiographic method using 18F (half-life: 109.8 min) was developed to detect 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) in mouse tissues. A linear relationship between the number of silver grains and corresponding 18F-radioactivity was observed. The half-distance of spatial resolution with 18F-micro-autoradiography was about 2.1 microns. The grain number increased with exposure time until 6 h, but 7 h or longer exposure induced a characteristic latent image fading. After i.v. injection of [18F]FDG into normal mice, the highest grain level among the hippocampal regions of the brain was found in the stratum lacunosum-moleculare followed by the dentate molecular and the stratum oriens. All granular and pyramidal cell layers showed lower grain levels than neuropil fields. In the pyramidal cell fields, the CA3a contained the highest grain level and the CA4 the lowest. This method requires only 4 h exposure and can be applied to all 18F-tracers to assess the tracer-tissue association.