Measurement of regional cerebral hemocirculation, oxygen and glucose metabolism in patients with untreated high grade gliomas using positron emission tomography (PET)

Hemocirculatory and metabolic indices of regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), oxygen extraction fraction (rOEF), cerebral oxygen consumption (rCMRO2) and cerebral glucose consumption (rCMRGl) were studied in eight patients with untreated high grade gliomas. Regions of interest (ROIs) were focused on the lesions corresponding to contrast enhanced area, the central low density area of the tumor and the peritumoral low density area on CT scans. In the viable portion of gliomas, rCBV (5.20±1.18ml/100ml, mean±SD, n=8) was significantly higher than that of the contralateral gray matter (P<0.05), which is suggestive of high vascularity, and rOEF (0.36±0.16) and rCMRO2 (1.66±0.45ml/100ml/min) values markedly decreased (P<0.05, P<0.01). rCBF (36.3±13.0ml/100ml/min) and rCMRG1 (5.94±1.15mg/100ml/min) was similar to that of the contralateral gray matter. A relative dissociation between oxygen and glucose metabolism indicates anerobic glycolysis in the energy metabolism of malignant gliomas. In the central low density area, rCBF, rCBV, rOEF, rCMRO2, rCMRG1 values decreased significantly from the viable portion and the contralateral gray matter. rOFF was markedly reduced in the central low density area, compared with that of the peritumoral low density area. The reduction suggested that tissue metabolic function was the first to fail, accompanied by autoregulatory impairment of vessels. In the peritumoral low density area, rCBF, rCBV, rCMRO2, rCMRG1 values were also lower than in the viable portion of gliomas and the contralateral gray matter. However, the rOEF was similar to the contralateral gray matter. A matched reduction of rCBF and rCMRO2 implies tissue metabolic failure and infiltration of tumor cells. (J.P.N.)