Characterizing Spondyloarthritis With 68Ga-FAPI PET/CT

Characterizing Spondyloarthritis With 68Ga-FAPI PET/CT

To evaluate the potential usefulness of 68Ga-FAPI PET/CT for the diagnosis, inflammation evaluation and prognosis prediction in spondyloarthritis.

Spondyloarthritis (SpA) is a chronic inflammatory rheumatic disease characterized by inflammatory back pain, enthesitis, dactylitis, and the formation of syndesmophytes, all of which significantly affect a patient's healthy functioning and general quality of life. Prevalence of underlying malignancy is high in patients with SpA. Radiographic sacroiliitis became a crucial finding in the diagnosis and classification of patients.

68Ga-FAPI has been developed as tracers specific for fibroblast-activation protein (FAP), which is overexpressed in activated fibroblasts in various type of cancers and autoimmune diseases, such as rheumatoid arthritis, IgG4-related diseases and interstitial lung diseases.

Recently the investigators have published articles of the application of 68Ga-FAPI in IgG4-related disease and rheumatoid arthritis, which showed it was more sensitive than FDG in detecting a certain type of inflammation. Increased 68Ga-FAPI Uptake in ankylosing spondylitis in a patient with rectal cancer has also been reported in a case report, indicating the potential utility of FAP-targeted PET/CT imaging for diagnosis and disease assessment in spondyloarthritis.

Thus, this prospective study is going to investigate utility of 68Ga-FAPI PET/CT in diagnosis of spondyloarthritis as well as inflammation assessment in joints including the sacroiliac (SI) joints, spine and peripheral joints. Also, this study aims to investigate potential utility of 68Ga-FAPI PET/CT in predicting treatment response and disease prognosis such as formation of syndesmophytes and erosive changes.

Inclusion Criteria:

1. A diagnosis of SpA according to the ASAS (Assessment of Spondyloarthritis International Society) classification criteria for SpA.
2. Adult men or women 18 and ≤ 65 years of age at the time of signing the informed consent (ICF).
3. participants who were able to provide informed consent (signed by participant or legal representative) and assent according to the guidelines of the Clinical Research Ethics Committee.

Exclusion Criteria:

1. Pregnancy;
2. Breastfeeding;
3. known allergy against FAPI;
4. any medical condition that in the opinion of the investigator may significantly interfere with study compliance.