Individualized discrimination of tumor progression from treatment-related changes in different types of adult-type diffuse gliomas using [ 11 C]methionine PET

Purpose This study aimed to assess the ability of [ 11 C]methionine (MET) PET in distinguishing between tumor progression (TP) and treatment-related changes (TRCs) among different types of adult-type diffuse gliomas according to the 2021 World Health Organization classification and predict overall survival (OS). Methods We retrospectively selected 113 patients with adult-type diffuse gliomas with suspected TP who underwent MET PET imaging. Maximum and mean tumor-to-background ratios (TBR max , TBR mean ) and metabolic tumor volume (MTV) were calculated. Diagnoses were verified by histopathology (n = 50) or by clinical/radiological follow-up (n = 63). The diagnostic performance of MET PET parameters was evaluated through receiver operating characteristic (ROC) analysis and area under the curve (AUC) calculation. Survival analysis employed the Kaplan–Meier method and Cox proportional-hazards regression. Results TP and TRCs were diagnosed in 76 (67%) and 37 (33%) patients, respectively. ROC analysis revealed TBR max had the best performance in differentiating TP from TRCs with a cut-off of 1.96 in IDH -mutant astrocytoma (AUC, 0.87; sensitivity, 93%; specificity 69%), 1.80 in IDH -mutant and 1p/19q-codeleted oligodendroglioma (AUC, 0.96; sensitivity, 100%; specificity, 89%), and 2.13 in IDH wild-type glioblastoma (AUC, 0.89; sensitivity, 89%; specificity, 78%), respectively. On multivariate analysis, higher TBR mean and MTV were significantly correlated with shorter OS in all IDH -mutant gliomas, as well as in IDH -mutant astrocytoma subgroup. Conclusion This work confirms that MET PET has varying diagnostic performances in distinguishing TP from TRCs within three types of adult-type diffuse gliomas, and highlights its high diagnostic accuracy in IDH -mutant and 1p/19q-codeleted oligodendroglioma and potential prognostic value for IDH -mutant gliomas, particularly IDH -mutant astrocytoma.