Clinical Utility of Fluorine-Fibroblast Activation Protein Inhibitor-04 Positron Emission Tomography/Computed Tomography in the Evaluation of Pancreatic Ductal Adenocarcinoma: Comparison With Fluorine-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography.

Pancreatic ductal adenocarcinoma (PDAC) is highly susceptible to metastasis, making early detection of metastases and associated risk factors crucial for effective management. This study aimed to assess the performance of fluorine (F)- fibroblast activation protein inhibitor-04 (F-FAPI-04) positron emission tomography/computed tomography (PET/CT) in detecting metastasis and predicting pathological characteristics and risk factors in 67 PDAC patients. Comparisons were made with F-fluorodeoxyglucose (F-FDG) PET/CT. Lesion identifications and radiotracer uptakes were evaluated through visual inspection and semiquantitative analysis using the maximum standardized uptake value (SUVmax). We analyzed the risk factors for metastasis and observed that F-FAPI-04 identified more positive lesions and showed significantly higher SUVmax values than F-FDG in both primary tumors and metastases, leading to upstaging in several cases. In primary tumors, F-FAPI-04 was associated with higher levels of poorly differentiated PDAC, compared to those with moderately differentiated tumors. Notably, the SUVmax of 18F-FAPI-04 in primary tumors demonstrated a significant correlation with pathological differentiation and served as an independent prognostic factor for peritoneal metastasis, rather than lymph node or liver metastasis. Our findings suggested that F-FAPI-04 PET/CT offers superior tumor detectability and improved node-metastasis (NM) staging in PDAC patients, positioning it as a more effective tool than F-FDG PET/CT.