Objective: The purpose of this study was to evaluate the efficacy of quantitative imaging of glucose metabolism with positron emission tomography (PET) using kinetic analysis for differentiating between high-grade glioma and central nervous system (CNS) lymphoma.
Methods: Dynamic fluorine-18-fluorodeoxyglucose (18F-FDG)-PET scans obtained in 20 patients with high-grade glioma (World Health Organization grade III, five lesions; grade IV, 15 lesions) and in 12 patients with CNS lymphoma (16 lesions) were retrospectively reviewed. Applying a three-compartment model, parametric images of K1, k2, k3, and k4 and cerebral metabolic rate of glucose (CMR(Glc)) were obtained.
Results: On visual analysis, one grade III glioma lesion showed an increase of K1, k2, and k3 values as observed on their respective images. Four grade IV glioma lesions showed an increase of K1 and k2, 11 of k3, and six of CMR(Glc) on their respective images. Fourteen CNS lymphoma lesions showed an increase of K1, 16 of k3, two of k4, and 14 of CMR(Glc). Both k3 and CMR(Glc) values (mean+/-SD) of CNS lymphoma (0.096+/-0.046 and 77.4+/-37.7, respectively) were significantly higher than those of the normal gray matter (0.059+/-0.015 and 41.3+/-9.3, respectively; P<0.007 and P<0.002, respectively). The k3 value of CNS lymphoma was significantly higher than that of grade III (0.058+/-0.022) and grade IV (0.065+/-0.024) gliomas (P<0.03 and P<0.04, respectively). The CMR(Glc) value of CNS lymphoma was significantly higher than that of grade III (33.8+/-7.8) and grade IV (41.5+/-23.1) gliomas (P<0.001 and P<0.004, respectively). The value of k2 of CNS lymphoma was significantly lower than that of grade IV glioma (P<0.05).
Conclusion: The direct measurement of the regional rate constants by kinetic analysis might be useful for the delineation of CNS lymphoma and for differential diagnosis of high-grade glioma and CNS lymphoma.