Exploring the Diagnostic Utility of 68 Ga-FAPI-46 PET/CT in Diverse Pulmonary Pathologies : A Comparative Analysis...

Lung cancer is the leading cause of cancer-related deaths globally. Computed tomography (CT) and 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET) often struggle to distinguish between benign and malignant lesions, prompting interest in newer tracers, such as 68 Ga-Fibroblast activation protein inhibitor (FAPI). This prospective study is a comparative analysis for lung lesion characterization using 68 Ga-FAPI-46 PET and 18 F-FDG PET.

Patients with suspected lung lesions underwent both 18 F-FDG and 68 Ga-FAPI PET/CT scans. Based on histopathology, they were classified into benign or malignant groups. PET-based semi-quantitative analysis was performed, and receiver operating characteristic (ROC) analysis was conducted to determine the optimal SUVmax cut-off for differentiating benign from malignant lesions.

Sixty-six patients were prospectively included in the study (mean age: 57.5±1.7 y) with 14 benign and 52 malignant lesions on histopathology. SUVmax of benign (9.8 vs. 8.8, P =0.6) and malignant lesions (14.7 vs. 13.5, P =0.8) were comparable on 68 Ga-FAPI and 18 F-FDG PET, respectively. However, a statistically significant difference was noted between the median SUVmax of benign and malignant lesions on 68 Ga-FAPI (9.8 vs. 14.7, P =0.002) and 18 F-FDG PET (8.8 vs. 13.5, P =0.001). ROC analysis revealed a SUVmax cut-off of 12.2 (sensitivity-73.1%, specificity-78.6%, AUC-0.77) and 9.5 (sensitivity-82.7%, specificity-64.3%, AUC-0.78) to differentiate benign from malignant lesions on 68 Ga-FAPI and 18 F-FDG PET, respectively.

68 Ga-FAPI-46 PET/CT exhibits potential as an alternative to FDG PET for lung lesion characterization, but requires cautious interpretation due to possible false-positive findings from benign lesions and false-negative findings from low-grade tumors, necessitating histopathologic confirmation.