Quantitative assessment of regional glucose metabolism in normal rats using semiconductor animal PET

Objectives A fine spatial resolution PET scanner with less than 1 mm FWHM using CdTe detectors was developed for in vivo imaging study. The purpose of this study was to evaluate the feasibility of absolute quantification of rCMRglc in rats using the semiconductor PETscanner (MIP-100, Sumitomo Heavy Industries Ltd., Tokyo, JAPAN).

Methods Six male Wistar rats were anesthetized by isoflurane and O2. Immediately after the injection of around 37 MBq18F-FDG, PET scanning was commenced for 3 hour scanning. Arterial blood samples were drawn over 70 min to determine the time courses of 18F-FDG. PET images were reconstructed using 3D-OSEM (iteration 3 and subset 8). rCMRglc valueswere calculated by autoradiographical method (Sokoloff et al., 1977) (PMOD Technologies, USA).

Results rCMRglc in fine areas were visualized. Average rCMRglc values were 42-53μmol/100g/min in cerebral cortex, 40-47μmol/100g/min in thalamus, 61μmol/100g/min in caudate-putamen, 41μmol/100g/min in hippocampus, and 75μmol/100g/min in inferior colliculous. Comparing with previous ex vivo data in the state of awake, the reduction of rCMRglc was substantial (40-75%).

Conclusions Absolute quantification of rCMRglc in normal rats was feasible using 18F-FDG and fine semiconductor PET, suggesting a useful modality for further in vivo experiments in rodents.