Increased F-FAPI uptake in bones and joints of lung cancer patients: characteristics and distributions.

Objective: This study investigated the distribution and characteristics of various bone and joint lesions on F-FAPI PET/CT in lung cancer patients.

Methods: Seventy-four lung cancer patients who underwent F-FAPI PET/CT were reviewed. Bone and joint lesions with elevated F-FAPI uptake were recorded and analyzed. The distribution and maximum uptake value (SUV) of different benign lesions or bone metastases were presented. In addition, the SUV of bone metastases on F-FDG and F-FAPI-04 PET/CT were also compared.

Results: In 53 patients, a total of 262 lesions presented F-FAPI accumulation. Bone metastases were mainly in vertebrae, pelvis, and ribs, while benign lesions were in vertebral margins, alveolar bone, and shoulder joints. The SUV of bone metastases was significantly higher than that of benign lesions ([Formula: see text] vs. [Formula: see text], [Formula: see text]), with NSCLC cases having higher SUV values than SCLC cases ([Formula: see text] vs. [Formula: see text], [Formula: see text]). Among benign lesions, arthritis and periodontitis demonstrated higher SUV than degenerative lesions (arthritis: [Formula: see text]; periodontitis: [Formula: see text]; degenerative diseases: [Formula: see text]; [Formula: see text] and [Formula: see text], respectively). The SUV of bone metastases was comparable between F-FDG and F-FAPI PET/CT. However, F-FAPI PET/CT was found to be superior in identifying cranial metastases compared to F-FDG PET/CT (TBR: [Formula: see text] vs. [Formula: see text], [Formula: see text]).

Conclusion: This study demonstrated that F-FAPI PET/CT is a valuable imaging modality for detecting bone and joint lesions in lung cancer patients. The SUV of malignant lesions was higher than that of benign lesions, but cannot accurately distinguish benign and malignant lesions. The uptake of FAPI differs among lesions with different pathological types.