Prognostic significance of 18F-FDG PET/CT parameters in IDH-1 wild-type GBM and correlation with molecular markers

To assess the prognostic role of metabolic parameters on 18F-FDG PET/CT & correlation with molecular markers in IDH-1 wild-type GBM.

A total of 129 patients with brain lesions showing equivocal findings on baseline MRI who were referred for fluoro-deoxy-glucose PET/CT were analyzed. Of these, 50 underwent surgery/biopsy and postoperative histopathological diagnosis of IDH-1 wild-type GBM. SUVmax, metabolic tumor volume (MTV), total lesion glycolysis (TLG) & T/w ratio was calculated. Median metabolic parameters were used for stratification. Overall survival was calculated using Kaplan-Meier method and was compared using log rank test. P value < 0.05 was considered significant. Multivariate analysis was done using Cox proportional hazard model. Correlation between metabolic parameters and molecular markers was done using Mann-Whitney U test.

Median of SUVmax, T/w ratio, MTV, TLG, 18.3, 2.09, 61, 409. Average overall survival (OS) for T/w ratio >2.08 was 5 months, <2.08 was 18 months (P value 0.001). For MTV >61 was 4 months, <61 was 18 months (P value 0.001). Similarly, for TLG >409 was 5 months while for <409 was 19 months (P value 0.001). SUVmax was not significant for OS. In multivariate analysis, age was the statistically significant independent prognostic factor.

Metabolic parameters of fluoro-deoxy-glucose PET/CT help in prognosticating IDH-1 wild-type GBM. Higher MiB-1 index correlates with higher T/w ratio and is associated with poor overall survival.