¹⁸ F-FDG and ⁶⁸ Ga-FAPI PET/CT Imaging in a Patient with High-Grade Meningioma: A Case Report.

Abstract

High-grade meningiomas exhibit aggressive biological behavior and may benefit from functional imaging for further characterization. We report a 50-year-old female presenting with a 1-year history of intermittent right-sided headache and recurrent seizures. Contrast-enhanced magnetic resonance imaging demonstrated a well-defined extra-axial mass arising from the right sphenoid wing dura mater, accompanied by hyperostosis, dural tail sign, and vasogenic edema. ¹⁸ F-FDG and ⁶⁸ Ga-FAPI PET/CT ( ⁶⁸ Ga-fibroblast activation protein inhibitor positron emission tomography/computed tomography) were performed 1 week apart. FDG PET/CT demonstrated a tumor SUVmax of 7.08, comparable to the contralateral substantia nigra (SUVmax 7.27), resulting in limited lesion-to-background contrast (T/N ratio 0.97). In contrast, FAPI PET/CT showed tumor SUVmax of 3.02, with the aorta used as the background reference (SUVmean 1.76), yielding a tumor-to-background ratio of 1.71 and improved visual delineation due to minimal physiological brain uptake. Histopathology confirmed atypical meningioma (World Health Organization grade II). Although FAPI demonstrated higher tumor-to-background contrast than FDG, uptake remained relatively mild, suggesting predominant stromal mesenchymal involvement. Further comparative studies with established modalities such as somatostatin receptor PET are warranted.