Clinical Utility of FAPI PET/CT in Diagnosis, Staging, and Response Assessment of Colorectal Cancer

Colorectal cancer (CRC) remains one of the most common and deadly malignancies worldwide. Accurate diagnosis, staging, and treatment monitoring are critical for optimizing patient outcomes. Although ¹⁸F-FDG PET/CT is widely utilized in CRC imaging, its diagnostic accuracy can be limited by variable avidity across histologic subtypes and by physiological bowel uptake. Fibroblast activation protein (FAP)-targeted positron emission tomography (FAPI PET/CT) has recently emerged as a promising molecular imaging modality that visualizes cancer-associated fibroblasts (CAFs) within the tumor microenvironment. Compared with FDG, FAPI PET/CT provides markedly improved tumor-to-background contrast and higher sensitivity in detecting both primary and metastatic CRC lesions. Beyond its diagnosis and staging utility, FAPI PET/CT offers valuable potential for therapy guidance, treatment response assessment, and prognostic evaluation. Integration with theranostic approaches further enables a comprehensive "see-and-treat"paradigm. FAPI PET/CT represents a transformative advance in CRC management, offering high-contrast, noninvasive visualization of tumor-stroma interactions and facilitating personalized treatment strategies. While current evidence remains preliminary and largely based on small-scale studies, ongoing clinical trials and technological innovations are expected to further define and expand its clinical applications in colorectal cancer.