Low false-positive lymph nodes for 18F-fibroblast activation protein inhibitors PET/computed tomography in preoperative staging of patients with nonsmall cell lung cancer.

Abstract

This study aimed to evaluate the diagnostic accuracy of 18F-fibroblast activation protein inhibitor (FAPI) PET/computed tomography (CT) in identifying primary tumors and mediastinal lymph node metastases in nonsmall cell lung cancer (NSCLC), with histopathological findings serving as the reference standard. Nineteen patients underwent preoperative 18F-FAPI PET/CT and subsequent surgery; of these, 13 also underwent 18F-fluorodeoxyglucose (FDG) PET/CT within 1 week. The diagnostic accuracy of primary tumors and lymph node metastases was evaluated for both modalities. Semiquantitative parameters, including maximum standardized uptake values (SUVmax) and target-to-background ratios (TBRs), for both primary tumors and lymph node metastases were assessed for both modalities. For primary tumors, 18 of 19 (94.7%) showed positive results on 18F-FAPI PET/CT scans. In 13 patients who also underwent 18F-FDG PET/CT, 18F-FAPI PET/CT demonstrated a higher detection rate compared with 18F-FDG PET/CT (100% vs. 69.1%). The overall accuracy of lymph node assessment with 18F-FAPI PET/CT (95.9-97.1%) was significantly higher compared to 18F-FDG PET/CT (51.0%). Malignant lymph nodes exhibited significantly higher SUVmax and TBR on 18F-FAPI scans (SUVmax: 7.0 vs. 0.9, P < 0.001; TBRmuscle: 5.0 vs. 0.8, P < 0.001) than on 18F-FDG scans (SUVmax: 3.9 vs. 1.8, P = 0.01), except for the liver TBR on 18F-FDG scans (TBRliver: 1.8 vs. 1.0, P = 0.055). 18F-FAPI could be utilized in the preoperative staging of NSCLC to mitigate the incidence of false positives associated with 18F-FDG, due to its higher accuracy in identifying mediastinal lymph node metastasis.