In vivo measurements of regional cerebral hemocircuration and metabolism in gliomas using 15O and 18F-fluorodeoxyglucose positron emission tomography

A high resolution PET-HEADTOME III have been employed to quantitate regional cerebral hemodynamics and metabolism in gliomas using O-15 and 18FDG tracers, and to evaluate histological malignancy preoperatively. Hemodynamic and metabolic indices of regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), oxygen consumption (rCMRO2), oxygen extraction (rOEF), and glucose consumption (rCMRGl) were studied on thirteen preoperative gliomas involving one recurrent case. Regions of interest (ROIs) on PET were placed over the corresponding lesions in CT scans. In high grade gliomas, ROIs were also focused on the corresponding parts of central low density area, contrast enhanced area, and peritumoral low density area. rCBF and rCBV were variable and unrelated in both low and high grade gliomas. rCMRGl values were 5.99 +- 3.99 mg/100 ml/min for high grade gliomas, and 3.01 +- 0.48 mg/100 ml/min for low grade gliomas. Lesions with high uptake of radioisotope were proved to be high grade gliomas. Lesions with low uptake being low grade gliomas. In comparison with the contralateral gray matter around the sylvian fissure, rCBV was significantly higher (p < 0.02) in high grade gliomas, and rCMRGl was lower (p < 0.05) in low grade gliomas. rCMRO2 and rOEF values were reduced markedly (p < 0.01) in both low and high grade gliomas. These results support that anerobic glycolysis increased with malignancy in the metabolism of gliomas. The hemodynamics and metabolism of central low density area and peritumoral low density area reflect the pathophysiological state of necrosis and edema respectively. PET has been a convincing tool to provide satisfactory informations on biological characteristics in the diagnosis of malignancy of gliomas, and should ultimately make it possible to plan an appropriate therapy. (author)