Developmental changes of cerebral blood flow and oxygen metabolism in children

BACKGROUND AND PURPOSE: Normal values for cerebral blood flow (CBF) and metabolism in adults are well established, but not for children. Our goal, therefore, was to clarify functional developmental changes of the brain in children in relation to CBF and oxygen metabolism. METHODS: We measured regional CBF (rCBF), regional cerebral metabolic rate for oxygen (rCMRO(2)), and regional oxygen extraction fraction (rOEF), using positron emission tomography (PET). We performed 30 PET studies in 24 children ages 10 days to 16 years (nine boys, 15 girls), using a steady inhalation method with (CO2)-O-15, O-15(2), and (CO)-C-15 in order to measure rCBF, rCMRO(2), and rOEF, respectively. Regions of interest were set in the primary cerebral areas (sensorimotor, visual, temporal, and parietal cortex), cerebral association areas (frontal and visual association), basal ganglia (lenticular and thalamus), and posterior fossa (brain stem and cerebellar cortex). Subjects were grouped by age (<1, 1 to <3, 3 to <8, and greater than or equal to 8 years), and the absolute values of the parameters were compared with those obtained from 10 healthy adults. RESULTS: rCBF and rCMRO(2) were lower in the neonatal period than in older children and adults, and increased significantly during early childhood. rCBF was higher as compared with adults, peaking around age 7, whereas rCMRO(2) was relatively high, with the last area to increase being the frontal association cortex. Both rCBF and rCMRO(2) reached adult values during adolescence. No difference in rCBF was observed between the basal ganglia and the primary cerebral cortex; however, it was prominent in the occipital lobe in every age bracket. No significant changes in rOEF were found during childhood. CONCLUSION: The dynamic changes of rCBF and rCMRO(2) observed in children probably reflect the physiologic developmental state within anatomic areas of the brain.