Ga-68-FAPI-46 PET for CRC Recurrence Detection in Elevated CEA

Colorectal cancer (CRC) is one of the leading causes of cancer-related mortality, with a significant recurrence rate following curative surgery, particularly in stages II and III. Early detection of asymptomatic recurrence is critical for initiating salvage treatment. Serum CEA elevation is a marker for recurrence, necessitating advanced imaging tools for precise localization. This study evaluates the use of Ga-68-FAPI-46, a novel imaging agent targeting fibroblast activation protein (FAP), which is overexpressed in the tumor stroma. Ga-68-FAPI-46 demonstrates higher tumor uptake and faster clearance from normal tissues compared to F-18-FDG, offering a potential diagnostic advantage. Participants will undergo both F-18-FDG PET and Ga-68-FAPI-46 PET scans, with lesion detection validated through pathology or clinical follow-up. The trial aims to determine the diagnostic performance of Ga-68-FAPI-46 PET in terms of sensitivity, specificity, positive predictive value, and negative predictive value, using the McNemar test for statistical comparison. The study also emphasizes participant safety and data protection, adhering to Good Clinical Practice (GCP) guidelines.