Glioblastoma multiforme (GBM) is an aggressive primary brain tumor with a high recurrence despite multimodal therapy. Magnetic resonance imaging done after treatment can be limited by radiation necrosis, while F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) suffers from high cortical background activity. We present the case of recurrent GBM in which Ga-68 Fibroblast Activation Protein Inhibitor (FAPI) PET/CT demonstrated intense uptake with higher tumor-to-background contrast compared with FDG PET/CT. This case demonstrates the diagnostic potential of FAPI imaging in recurrent GBM and highlights its emerging theranostic relevance as a biomarker for FAPI-targeted radionuclide therapy.
Bishnoi et al. (2026) studied this question.