In vivo disturbance of the oxidative metabolism of glucose in human cerebral gliomas

Abstract

Abnormalities in the oxidative metabolism of glucose in human cerebral gliomas were studied in 7 patients using positron emission tomography. Measurements of regional cerebral blood flow and O2 consumption were obtained using the [15O] steady-state inhalation technique. Values of regional cerebral glucose consumption were obtained using [18F]-2-fluoro-2-deoxy-D-glucose and a simplification of the method of Sokoloff. Functional values were obtained for regions of tumor and brain tissue in the middle cerebral artery territory of the contralateral cortex. Values of regional glucose consumption were calculated for both regions using a value of the lumped constant quoted for normal brain tissue (0.42). Tumor regional cerebral blood flow was comparable to that in the contralateral cortex, whereas regional cerebral oxygen consumption was depressed. This depression resulted in low tumor values of the fractional oxygen extraction ratio (0.21 .+-. 0.07), indicating that O2 supply exceeded the metabolic demand. Tumor regional cerebral glucose consumption was not depressed and regional glucose extraction ratios were similar for tumor and brain tissue. The metabolic uncoupling between regional O2 consumption and regional glucose consumption (CMRO2/CMRGlu = 0.24 .+-. 0.07 ml O2/mg glucose) is indicative of increased aerobic glycolysis.