[Positron emission tomography (PET) study in patients with meningiomas]

Abstract

Regional hemocirculation and metabolism were evaluated in five patients with meningiomas using positron emission tomography (PET). Histological diagnoses were: two cases of meningotheliomatous type, one hemangiopericytic type, one fibroblastic type, and one transitional type. Regional cerebral blood flow (rCBF), blood volume (rCBV), oxygen extraction fraction (rOEF), and metabolic rates of oxygen (rCMRO2) and glucose (rCMRG1) were measured with 15O2, C15O. 15O2, and 18F-fluorodeoxyglucose tracers. For the quantitative analysis, regions of interest were delineated on tumors, the peritumoral region, and the contralateral gray matter in comparison with age-corresponding 5 malignant gliomas and 5 normal volunteers. Tumor hemocirculatory parameters (rCBF: 57.2 +/- 22.6 ml/100 ml/min, rCBV: 7.95 +/- 3.27 ml/100 ml, mean + SD, n = 5) were markedly higher than those of the contralateral gray matter (p less than 0.05 by a Student-t test). The high values were consistent with angiographic findings of tumor staining and with abundant tumor vessels demonstrated by pathological examination. rCMRO2 was 2.15 +/- 0.80 ml/100 ml/min, which were comparable to those of the contralateral gray matter. Tumor rCMRG1 showed 4.76 +/- 2.37 mg/100 ml/min; the values of two cases were similar to the respective gray matter. The raised metabolic rate (rCMRO2/rCMRG1) therefore suggests rather aerobic glycolysis as compared with gliomas. Low rOEF (0.26 +/- 0.16) reveals an excessive blood flow beyond oxygen demand of the tumor. In the peritumoral regions, rCBF and metabolism fell slightly but rOEF reached a level similar to the contralateral gray matter, possibly due to hemocirculatory stasis caused by intracranial hypertension; in contrast, an unmatched reduction of rCBF and rCMRO2 implies tumor cells infiltration in gliomas.(ABSTRACT TRUNCATED AT 250 WORDS)