REGIONAL CEREBRAL OXIDATIVE AND TOTAL GLUCOSE CONSUMPTION DURING RESTAND ACTIVATION STUDIED WITH POSITRON EMISSION TOMOGRAPHY

The relationship between regional oxidative and total rCMR(glc) in fiv e healthy volunteers in activated and non-activated areas of the brain has been investigated with positron emission tomography (PET). The tr acers [1-C-11]-D-glucose and [2-F-18]2-fluoro-2-deoxy-D-glucose were u sed. 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 meas ure the total rate of glucose consumption. Regional activation was per formed (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 va lues of total and oxidative rCMR(glc), when calculated for each volume element of the brain and displayed in a scatter plot, were found to b e symmetrically grouped around a straight line which passes close to t he origin. The slope of this line varied between the subjects. This in dicates that, on the average, the fraction of non-oxidative glucose ut ilization is constant within each subject, regardless of the value of rCMR(glc) and, further, that the fraction of non-oxidative glucose uti lization 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-ac tivated area. Our interpretation of the difference is that regional ac tivation increases the fraction of non-oxidative glucose consumption. This interpretation is supported by a previous PET study using [O-15]O -2, and by studies using MRS technique.