Measurement of the ratio of cerebral oxygen consumption to glucose utilization by positron emission tomography: Its consistency with the values determined by the Kety-Schmidt method in normal volunteers

The regional relationship between cerebral oxygen consumption (CMRO₂) and cerebral glucose utilization (CMRGlc) was studied in normal subjects using positron emission tomography (PET) and the ¹⁵O steady-state inhalation and the [¹⁸F]fluoro deoxyglucose method. The use of standard sets of rate constants and the model lumped constant of 0.52 as well as the regional blood-brain partition coefficient for water and the blood volume correction for oxygen extraction fraction provided a CMRO₂/CMRGcl ratio of 4.89 in the cortical gray matter, 5.27 in the basal ganglia and 5.82 in the centrum semiovale (white matter). The values of CMRO₂/CMRGlc for the basal ganglia and the white matter were consistent with those reported for the whole brain with the Kety-Schmidt method. There was no significant difference in the CMRO₂/CMRGlc between the basal ganglia and the white matter indicating the similar nature of in vivo oxidative metabolism of glucose in neuron-rich region and glial cell-rich region.