Fibroblast Activation Protein (FAP) specific PET for advanced target volume delineation in glioblastoma

•In an analysis of 13 patients who underwent both, FAP-specific PET and MRI, the resulting volumes were incongruent.•No complications occurred during either MRI or FAP-specific PET.•FAP-specific PET provides additional information for radiotherapy planning and might prove useful for biopsy planning given the heterogeneous tracer enhancement. Fibroblast Activation Protein (FAP)-specific Positron Emission Tomography (PET) has shown promising results in various cancers. This pilot study compares FAP-specific PET to MRI for treatment planning in 13 Glioblastoma patients. The resulting incongruent volumes could provide additional information for radiotherapy or biopsy planning.