Objective To investigate the application value of tumor metabolic parameters derived from ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in differentiating different grades of gliomas and primary central nervous system lymphoma (PCNSL).

Methods A retrospective analysis was conducted on the preoperative general data and ¹⁸F-FDG PET/CT images of 30 patients (with a total of 56 lesions) pathologically diagnosed as glioma and PCNSL. The differences of the lesion morphology (long diameter, peritumoral edema and space-occupying effect) and metabolic parameters standardized maximum uptake (SUVmax), standardized mean uptake (SUVmean), tumor to background ratio (TBR), metabolic tumor volume (MTV) were analyzed. The diagnostic efficacy of each parameter was analyzed using the receiver operating characteristic (ROC) curve, and the cut-off values were calculated.

Results There was no statistical significance in the tumor long diameter, peritumoral edema and space-occupying effect between glioma and PCNSL (P ＞ 0.05). The metabolic parameters (SUVmax, SUVmean, TBR and MTV) of PCNSL were significantly higher than those of glioma (P ＜ 0.05 to P ＜ 0.01). The comparison of glioma subgroups of different grades showed that the metabolic parameters in WHO grade 4 glioma were significantly higher than those in WHO grade 2 and grade 3 glioma (P ＜ 0.01), and the metabolic parameters of WHO grade 3 glioma were similar to those of WHO grade 2 glioma (P ＞ 0.05). The ROC curve showed that the areas under the curve (AUC) of SUVmax, SUVmean, TBR, and MTV in differentiating glioma from PCNSL were 0.875, 0.865, 0.791, and 0.657, respectively. The cut-off value, sensitivity and specificity were 19.40, 82.1% and 91.6%; 12.95, 77.8% and 89.7%; 1.64, 70.4% and 72.4%; 16.50, 66.7% and 62.1%, respectively (P ＜ 0.05).

Conclusions The ¹⁸F-FDG PET/CT, based on the analysis of tumor metabolic heterogeneity, has important value in the differential diagnosis of different grades of gliomas and PCNSL.