Regional Kinetic Constants and Cerebral Metabolic Rate for Glucose in Normal Human Volunteers Determined by Dynamic Positron Emission Tomography of [18F]-2-Fluoro-2-Deoxy-D-Glucose

Using dynamic [ 18 F]fluorodeoxyglucose (FDG) positron emission tomography with a high-resolution, seven-slice positron camera, the kinetic constants of the original three-compartment model of Sokoloff and co-workers (1977) were determined in 43 distinct topographic brain regions of seven healthy male volunteers aged 28–38 years. Regional averages of the cerebral metabolic rate for glucose (CMR glu ) were calculated both from individually fitted rate constants (CMR glu kinetic) and from activity maps recorded 30–40 min after FDG injection, employing a four-parameter operational equation with standard rate constants from the literature (CMR glu autoradiographic). Metabolic rates and kinetic constants varied significantly among regions and subjects, but not between hemispheres. k 1 ranged between 0.0485 ± 0.00778 min −1 in the oval center and 0.0990 ± 0.01347 min −1 in the primary visual cortex. k 2 ranged from 0.1198 ± 0.01533 min −1 in the temporal white matter to 0.1472 ± 0.01817 min −1 in the cerebellar dentate nucleus. k 3 was lowest (0.0386 ± 0.01482 min −1 ) in temporal white matter and highest (0.0823 ± 0.02552 min −1 ) in the caudate nucleus. Maximum likelihood cluster analysis revealed four homogeneous groups of brain regions according to their respective kinetic constants: (1) white matter and mixed brainstem structures; (2) cerebellar gray matter and hippocampal formations; (3) basal ganglia and frontolateral and primary visual cortex; and (4) other cerebral cortex and thalamus. Across the entire brain, k 1 and k 2 were positively correlated (r = 0.79); k 1 and k 3 showed some correlation (r = 0.59); but no significant linear association was found between k 2 and k 3 . A strong correlation with CMR glu could be demonstrated for k 1 (r = 0.88) and k 3 (r = 0.90), but k 2 was loosely correlated (r = 0.56). CMR glu kinetic ranged from 17.0 ± 2.45 μmol/100 g/min in the occipital white matter to 41.1 ± 5.62 μmol/100 g/min in the frontolateral cortex. In most regions the mean values of CMR glu kinetic did not differ significantly from CMR glu autoradiographic. With few exceptions, however, within-region variance was significantly less for CMR glu kinetic than for CMR glu autoradiographic, suggesting greater individual reliability of results obtained by the kinetic approach.