Increased 18F-FAPI uptake in bones and joints of lung cancer patients: characteristics and distributions

Skeletal Radiol. 2023 Dec;52(12):2377-2386. doi: 10.1007/s00256-023-04335-2. Epub 2023 May 2.


Objective: This study investigated the distribution and characteristics of various bone and joint lesions on 18F-FAPI PET/CT in lung cancer patients.

Methods: Seventy-four lung cancer patients who underwent 18F-FAPI PET/CT were reviewed. Bone and joint lesions with elevated 18F-FAPI uptake were recorded and analyzed. The distribution and maximum uptake value (SUVmax) of different benign lesions or bone metastases were presented. In addition, the SUVmax of bone metastases on 18F-FDG and 18F-FAPI-04 PET/CT were also compared.

Results: In 53 patients, a total of 262 lesions presented 18F-FAPI accumulation. Bone metastases were mainly in vertebrae, pelvis, and ribs, while benign lesions were in vertebral margins, alveolar bone, and shoulder joints. The SUVmax 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 SUVmax values than SCLC cases ([Formula: see text] vs. [Formula: see text], [Formula: see text]). Among benign lesions, arthritis and periodontitis demonstrated higher SUVmax 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 SUVmax of bone metastases was comparable between 18F-FDG and 18F-FAPI PET/CT. However, 18F-FAPI PET/CT was found to be superior in identifying cranial metastases compared to 18F-FDG PET/CT (TBRmet/brain: [Formula: see text] vs. [Formula: see text], [Formula: see text]).

Conclusion: This study demonstrated that 18F-FAPI PET/CT is a valuable imaging modality for detecting bone and joint lesions in lung cancer patients. The SUVmax 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.

Keywords: Bone metastases; Differential diagnosis; Fibroblast activation protein inhibitor; Lung cancer; PET/CT.

MeSH terms

  • Arthritis*
  • Fluorodeoxyglucose F18
  • Humans
  • Lung Neoplasms* / diagnostic imaging
  • Periodontitis*
  • Positron Emission Tomography Computed Tomography


  • Fluorodeoxyglucose F18