Pictorial Essay of Gallium-68-Fibroblast Activation Protein Inhibitor (FAPI) in Oncological Malignancies: Clinical Experience at Ocean Road Cancer Institute

The type II transmembrane protease known as fibroblast activation protein (FAP) is not present in quiescent fibroblasts but is extensively expressed in cancer-associated fibroblasts (CAFs). FAPI expression has been linked to a bad prognosis and increased treatment resistance. FAPI has demonstrated variable expressions in different tumors; high expression has been observed in desmoplastic tumors, these tumors (such as breast, colon and pancreatic carcinoma) have high concentrations of CAF’s and mesenchymal tumors (such as sarcoma) which express FAP in both CAF’s and tumor cells. FAP demonstrates poor expression in tumors with no significant desmoplastic reaction, such as lymphoma, myeloma, melanoma, RCC, seminoma, and multiple myeloma. Our pictorial review aims to demonstrate FAPI expression of the ⁶⁸ Ga-FAPI PET performed at our institute.