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This study investigates the value of fluorine 18 (18F)-labeled fibroblast activation protein inhibitor (FAPI) for lymph node (LN) metastases in patients with stage I-IIIA non-small cell lung cancer (NSCLC). From November 2021 to October 2022, 53 patients with stage I-IIIA NSCLC who underwent radical resection were prospectively included. 18F-fluorodeoxyglucose (FDG) and 18FFAPI examinations were performed within one week. LN staging was validated using surgical and pathological findings. 18FFDG and 18FFAPI uptake was compared using the Wilcoxon signed-ranks test. Furthermore, the diagnostic value of nodal groups was investigated. In 53 patients (median age, 64 years, range: 31-76 years), the specificity of 18FFAPI for detecting LN metastasis was significantly higher than that of 18FFDG (P < 0.001). High LN risk category, greater LN short-axis dimension(≥ 1.0 cm), absence of LN calcification or high-attenuation, and higher LN FDG SUVmax (≥ 10.1) were risk factors for LN metastasis(P < 0.05). The concurrence of these four risk factors accurately predicted LN metastases (Positive Predictive Value PPV 100%), whereas the presence of one to three risk factors was unable to accurately discriminate the nature of LNs (PPV 21.7%). Adding 18FFAPI in this circumstance improved the diagnostic value. LNs with an 18FFAPI SUVmax<6.2 were diagnosed as benign (Negative Predictive Value 93.8%), and LNs with an 18FFAPI SUVmax≥6.2 without calcification or high-attenuation were diagnosed as LN metastasis (PPV 87.5%). Ultimately, the integration of 18FFDG and 18FFAPI PET/CT resulted in the highest accuracy for N stage (83.0%) and clinical decision revisions for 29 patients. In patients with stage I-IIIA NSCLC, 18FFAPI contributed additional valuable information to reduce LN diagnostic uncertainties after 18FFDG PET/CT. Integrating 18FFDG and 18FFAPI PET/CT resulted in more precise clinical decisions. The Chinese Clinical Trial Registry: ChiCTR2100044944 (Registered: 1 April 2021, https://www.chictr.org.cn/showprojEN.html?proj=123995 ).
Li et al. (Mon,) studied this question.