Assessment of the Metabolic Trapping Rate of FDG in Rat Brain Using Dual Tracer Autoradiography with ¹⁸F-FDG and ¹⁴C-FDG

Abstract

The dual tracer autoradiography using ¹⁸F-FDG and ¹⁴C-FDG was applied to the estimation of changes in the metabolic trapping rate in rat brain. Rats were infused with kainic acid (1μg/μL) into the right striatum 3 hours prior to the tracer experiment. ¹⁸F-FDG was intravenously injected into the rats, and ¹⁴C-FDG was injected 44 minutes after ¹⁸F-FDG injection. The rats were decapitated at 1 minute post-injection of ¹⁴C-FDG, and frozen brain sections were prepared. The slices were exposed on imaging plate for 1 hour, and ¹⁸F-FDG images (45 minutes) were obtained. After the decay of ¹⁸F, the same slices were contacted with imaging plate for 1 week, and ¹⁴C-FDG images (1 minute) were obtained. Radioactivity concentrations in cerebral cortex at 1 minute and 45 minutes after ¹⁸F-FDG injection were determined by the dissection method, the values were used to normalize ¹⁸F-FDG and ¹⁴C-FDG image. The subtraction image was made by subtracting the normalized ¹⁴C-FDG image from the ¹⁸F-FDG image. In the results, intrastriatal infusion of kainic acid significantly enhanced the metabolic trapping process of FDG. The dual tracer autoradiography with ¹⁸F-FDG and ¹⁴C-FDG seems to be useful to assess the metabolic trapping rate of FDG in brain injury.