Interesting Findings in 68 Ga-FAPI-46 PET/CT Imaging in a Patient With Glioblastoma Multiforme

A 55-year-old disabled man with glioblastoma multiforme was referred to us for fibroblast activation protein inhibitor (FAPI) PET/CT imaging. 68 Ga-DOTA-FAPI-46 scan revealed uptake in the primary tumor and unexpected uptakes in soft tissue, especially in periarticular regions. These latter foci were compatible with calcifications on the CT. One in the breast was compatible with fibrotic tissue, but 2 other foci, in the rectus abdominis and gallbladder wall, could not be correlated with the CT findings. In Neurogenic heterotopic ossification, hypoxia-associated oxidative stress results in the metaplastic transformation of fibroblasts. Abnormal differentiation of fibroblasts in neurogenic heterotopic ossification before ossification could explain radiolabeled FAPI avidity in the mentioned areas.