Comparative analysis of regional brain blood flow and glucose metabolism in focal cerebrovascular disease measured by dynamic positron emission tomography of fluorine-18-labelled tracers.

Regional cerebral blood flow (rCBF) and glucose metabolism (rCMRglc) were measured in 44 patients with various kinds of focal vascular brain lesions, using multislice positron emission tomography (PET). Haemodynamic data were obtained by a recently developed, non-invasive clearance method utilizing (18F)-methyl fluoride as a diffusible, gaseous indicator. Shortly after completion of each flow study, rCMRglc was dynamically determined by standard procedures using 2(18F)-fluorodeoxyglucose. While blood flow and glucose consumption in the structurally damaged area were often uncoupled during the acute phase, metabolism-to-flow ratios were markedly less scattered at later stages of cerebrovascular disease. Individual maximum-likelihood cluster analysis of brain regions revealed remarkable similarity between deactivation patterns of rCBF and rCMRglc, with Tanimoto coefficients averaging 0.56. This similarity was inversely related to the residual rCMRglc of the lesion. These findings are in line with results obtained by PET of other tracers, suggesting that the pair of methods provides valuable and somewhat complementary information on brain function and mechanisms of cerebral vascular disease.