抄録
Quantitative assessment of local cerebral glucose utilization (lCGU) with [18F] 2-fluoro-2-deoxy-D-glucose (18FDG) and of local cerebral protein synthesis (lCPS) with L-[1-14C]-valine (14C-valine) were simultaneously performed by double-tracer autoradiography in an implanted rat brain tumor model in awake animals. lCPS was measured by both the three-compartment kinetic method and the free 14C-valine washout method. In tumor tissue, the lCGU rate was significantly greater than that in control brain cortex (p<0.05). The lCPS rate was also significantly higher in tumor tissue than in normal brain cortical tissue (p<0.001), according to both methods of measurement. lCGU and lCPS were also assessed in peritumoral brain tissue. In the parietal cortex ipsilateral to the tumor, the lCGU rate was lower than that on the contralateral side and was reduced by 30% as compared to normal brain cortex (p<0.05). No significant difference in the lCPS rate was observed between the ipsilateral and contralateral cortices. Also, there was no significant difference in the lCPS rate as measured by the kinetic and 14C-valine washout methods. The results of this study imply that, in brain tumor tissue, the rate of protein synthesis is significantly greater than that of glucose utilization. The lCGU rate in the cortex ipsilateral to the tumor was always depressed, whereas the lCPS rate was similar in the two cortices. Histopathological evaluation revealed normal cell structure in the ipsilateral cortex. The author concludes that lCPS is a more suitable marker than lCGU in the evaluation of brain tissue function.
