Ga-FAPI-46 PET/CT in the evaluation of gliomas: comparison with F-FDG PET/CT and contrast-enhanced MRI.

This study compared Ga-FAPI-46 PET/CT, F-fluorodeoxyglucose (FDG) PET/CT, and contrast-enhanced MRI (CE-MRI) for glioma imaging, classification, and recurrence detection and explored PET parameters and molecular pathological profiles. Between June 2020 and June 2024, we prospectively enrolled patients with space-occupying lesions in the brain or previously treated gliomas. All patients underwent sequential CE-MRI, Ga-FAPI-46, and F-FDG PET/CT. Diagnostic accuracy was assessed based on a reference standard, and PET parameters were analysed for correlations with WHO grading and molecular characteristics. Forty-eight patients (median age, 51 years; 32 men) with 40 confirmed gliomas were enrolled. For primary tumour diagnosis, the sensitivity of Ga-FAPI-46 PET/CT was equivalent to CE-MRI (95% vs. 100%, = 0.99) and F-FDG PET/CT (95% vs. 77%, = 0.13). Ga-FAPI-46 uptake was higher in grade IV than in grade I-II gliomas (5.03 vs. 1.14, = 0.02). Ga-FAPI-46 PET/CT showed significantly higher maximum standardized uptake value and tumour-to-background ratio (TBR) in recurrent tumours than in treatment-related changes and demonstrated favourable sensitivity and specificity for detecting recurrent gliomas, though not significantly superior to F-FDG PET/CT (sensitivity: 100% vs. 85%, = 0.48; specificity: 100% vs. 80%, = 0.99) and CE-MRI (sensitivity: 100% vs. 100%, = NA; specificity: 100% vs. 40%, = 0.25). Glial fibrillary acidic protein-mutant gliomas exhibited higher Ga-FAPI-46 uptake than wild-type gliomas. Ga-FAPI-46 PET/CT outperformed F-FDG and CE-MRI in diagnosing glioma recurrence, although the results were not statistically significant. For primary glioma diagnosis, Ga-FAPI-46 PET/CT, despite having a better TBR, did not surpass F-FDG PET/CT and CE-MRI in terms of sensitivity and specificity. However, Ga-FAPI-46 PET/CT is superior to F-FDG for visualizing and classifying gliomas.