Regional cerebral oxidative and total glucose consumption during rest and activation studied with positron emission tomography

Abstract

The relationship between regional oxidative and total rCMR in five healthy volunteers in activated and non‐activated areas of the brain has been investigated with positron emission tomography (PET). The tracers [l‐^uC]‐D‐glucose and [2‐¹⁸F]2‐fluoro‐2‐deoxy‐D‐glucose were used. A previous study has shown that the former may be used to measure the rate of glucose oxidation while the latter tracer is used to measure the total rate of glucose consumption. Regional activation was performed (voluntary finger movements). Use of a computerized brain atlas enabled comparison between the regional oxidative and total rCMR_glc in each volume element of the brain for the group of subjects. The values of total and oxidative rCMR_gle, when calculated for each volume element of the brain and displayed in a scatter plot, were found to be symmetrically grouped around a straight line which passes close to the origin. The slope of this line varied between the subjects. This indicates that, on the average, the fraction of non‐oxidative glucose utilization is constant within each subject, regardless of the value of rCMR_gle and, further, that the fraction of non‐oxidative glucose utilization varies between subjects. The total and oxidative CMR_glc in the activated left hand area were 23.4 + 0.9% (mean + SEM) and 11.7 + 0.3%, respectively, higher than in the contralateral homologous non‐activated area. Our interpretation of the difference is that regional activation increases the fraction of non‐oxidative glucose consumption. This interpretation is supported by a previous PET study using [¹⁵0]O_a, and by studies using MRS technique.