A comparative study of bioradiography in human brain slices and preoperative PET imaging

Novel autoradiography (bioradiography) images in human neocortical brain slices which were obtained at operation from seven patients with intractable epilepsy who had received a 2-[18F]fluoro-2-deoxy-d-glucose-positron emission tomography (FDG-PET) examination preoperatively, were acquired in Krebs–Ringer medium (control condition) and that with high K+ (high K+ condition) containing FDG and compared with FDG-PET uptake. The FDG uptake images in rat brain slices were also acquired as a reference and compared with that in humans. In the slices incubated under high K+, FDG uptake in both human and rat gray matter was significantly enhanced, whereas that in the white matter was not. But the variance of uptake was larger in humans than the rats. This might indicate the different degree of progress of epilepsy in the sampled brain tissues. The uptake rates of FDG in human gray matter under the control condition showed an inverse correlation with those seen in PET, which were evaluated as sampled and contralateral gyri (SG/CG) and sampled gyri and cerebellar cortex (SG/CB) ratio. On the contrary, it showed a weak positive correlation with PET under the high K+ condition. The uptake rates of FDG in human gray matter expressed as a high K+/control ratio, closely matched that observed by FDG-PET, which were evaluated as the SG/CG ratio and the SG/CB ratio. Our experimental system provides useful information for the interpretation of PET data in epileptics and the theoretical basis to interpret the results of metabolic studies using living human brain tissues for further use in pharmacological manipulation.