Detection of Visual Activation in the Rat Brain Using 2-deoxy-2-[18F]fluoro-D-glucose and Statistical Parametric Mapping (SPM)

Purpose: This study was designed to assess changes in brain glucose metabolism in rats after visual stimulation. Materials and methods: We sought to determine whether visual activation in the rat brain could be detected using a small-animal positron emission tomography (PET) scanner and 2-deoxy-2[F-18]fluoro-D-glucose (FDG). Eleven rats were divided into two groups: (a) five animals exposed to ambient light and (b)six animals stimulated by stroboscopic light (10 Hz) with one eye covered. Rats were injected with FDG and, after 45 min of visual stimulation, were sacrificed and scanned for 90 min in a dedicated PET tomograph. Images were reconstructed by a three-dimensional ordered subset expectation maximization algorithm (1.8 mm full width at half maximum). A region-of-interest (ROI) analysis was performed on 14 brain structures drawn on coronal sections. Statistical parametric mapping (SPM) adapted for small animals was also carried out. Additionally, the brains of three rats were sliced into 20-mu m sections for autoradiography. Results: Analysis of ROI data revealed significant differences between groups in the right superior colliculus, right thalamus, and brainstem (p <= 0.05). SPM detected the same areas as the ROI approach. Autoradiographs confirmed the existence of hyperactivation in the left superior colliculus and auditory cortex. Conclusions: To our knowledge, this is the first report that uses FDG-PET and SPM analysis to show changes in rat brain glucose metabolism after a visual stimulus.