Role of Traditional CHO PET Parameters in Distinguishing IDH, TERT and MGMT Alterations in Primary Diffuse Gliomas

Objective: Isocitrate dehydrogenase (IDH) mutation, telomerase reverse transcriptase (TERT) promoter mutation and O-methylguanine-DNA methyltransferase (MGMT) promoter methylation status are diagnostic, prognostic, predictive and therapeutic biomarkers for primary diffuse gliomas, and this study aimed to explore the relationship between choline (CHO) positron emission tomography (PET) parameters and these molecular alterations.

Methods: Twenty-eight patients who were histopathologically diagnosed with primary diffuse glioma and underwent presurgical CHO PET/CT were retrospectively analyzed, and IDH, TERT and MGMT alterations were examined. The volume of interest (VOI) was semiautomatically defined based on standardized uptake value (SUV) thresholds, and 5 traditional CHO parameters, namely, SUVmax, SUVmean, metabolic tumor volume (MTV), total lesion CHO uptake (TLC) and tumor-to-normal contralateral cortex activity ratio (T/N ratio), were calculated. Wilcoxon rank-sum tests and receiver operating characteristic (ROC) curves were applied to evaluate the differences and performances of the CHO parameters, and their capability to stratify patient prognosis was also evaluated.

Results: All 5 parameters were significantly higher in IDH-wildtype gliomas than in IDH-mutant gliomas (p = 0.0001-0.037), and SUVmax, SUVmean, TLC and the T/N ratio exhibited good performances in distinguishing the IDH status (areas under the ROC curve (AUCs) 0.856-0.918, accuracies 0.857-0.893) as well as stratifying patient prognosis. Although the differences and performances of the traditional parameters in distinguishing diverse TERT and MGMT statuses were moderate in the whole population, the T/N ratio and TLC displayed certain predictive value in discriminating the TERT status in the IDH-mutant and IDH-wildtype subgroups (p = 0.028-0.048, AUCs 0.857-0.860, accuracies 0.800-0.917, respectively).

Conclusions: Traditional CHO PET parameters are capable of distinguishing IDH but not TERT or MGMT alterations in the whole population. In accordance with the clinical understanding of TERT promoter mutations, the T/N ratio and TLC can also discriminate the TERT status in IDH subgroups.