[Cerebral blood flow, cerebral blood volume, oxygen utilization and oxygen extraction fraction: the influence of age].

OBJECTIVE To analyze the changes of cerebral blood flow (CBF), cerebral blood volume (CBV), oxygen utilization (CMRO2) and oxygen extraction fraction (OEF) with age. METHODS The PET images of 7 young (21.0-/+1 years old) and 7 aged volunteers (60.9-/+4.7 years old) were analyzed to identify the areas where CBF, CBV, CMRO2, OEF had significant differences with age. The images were anatomically normalized by statistical parametric mapping (SPM2). A voxel by voxel calculation was performed to obtain the slope with age. Voxels which had statistically significant differences (P<0.05) with age were shown both on global and ROIs brain images. RESULTS The CBF decreased with age as was consistent with previous reports. The age-related changes in CBV and CMRO2 were similar to CBF, but OEF increased with age. CONCLUSION CBF, CBV and CMRO2 generally decline with age. The increase in OEF with age suggests a greater reduction in CBF than in CMRO2. The most significant decreases of CBF and CMRO2 occur in the convexity of the frontal cortex and inferior parietal cortex in all the functional images, while in the white matter, the influence of age is minimal.