CEREBRAL GLUCOSE UTILIZATION, AS MEASURED WITH POSITRON EMISSION TOMOGRAPHY IN 21 RESTING HEALTHY MEN BETWEEN THE AGES OF 21 AND 83 YEARS

Abstract

Positron emission tomography (PET) scanning with ¹⁸F-2-deoxy-D-glucose was employed to examine hemispheric and regional rates of cerebral glucose utilization in 21 resting healthy men between the ages of 21 and 83 years. The eyes of the subjects were covered and the external auditory canals were plugged with cotton in the 45 minutes following injection of tracer. Mean hemispheric cerebral metabolic rates for glucose (CMR_glc) averaged 4.3 to 4.4 mg. 100 g⁻¹. min⁻¹, and mean hemispheric grey matter glucose utilization, (CMR_glc)_grey, averaged 5.2 to 5.3 mg. 100 g⁻¹. min⁻¹. Neither parameter was correlated significantly with age, nor were their right/left ratios correlated with age (P > 0.05). The mean ratios, furthermore, did not differ significantly from 1. Regional cerebral metabolic rates for glucose, rCMR_glc, at each of 31 identified midline and bilateral structures also were not correlated significantly with age. Mean rCMR_glc ranged from 2.6 mg. 100 g⁻¹. min⁻¹ at the centrum semiovale to 6.2 mg. 100 g⁻¹. min⁻¹ at the precentral gyrus of the frontal lobe and precuneus of the parietal lobe. The results indicate that the cerebral metabolic rate for glucose is not correlated with age in healthy men.