Objectives: Aim of the current study was to evaluate the relationships between the findings of 18F-fluoride PET/CT (F-PET/CT) reflecting osteo-proliferative processes and the clinical indexes related to the disease activity. The clinical indexes are Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Ankylosing Spondylitis Disease Activity Score (ASDAS).
Methods: We studied 29 AS patients aged 26-69 years with a wide range of disease activity using F-PET/CT. The number of regions of high bone turnover or osteoarthritis features at the spine and at sacroiliac joints was counted.
Results: The number of F-PET/CT positive sites was significantly higher in patients with severe functional impairment and higher disease activity and it was positively related to both BASDAI (r = 0.336; P = 0.036) and ASDAS (r = 0.408; P = 0.014) while the number of degenerative features (osteoarthritis) was related neither with functional impact nor with disease activity.
Conclusions: With a single examination, F-PET/CT accurately identifies the functional impairment and the clinical involvement of AS. The good correlation we found between the number of F-PET/CT positive sites and disease activity candidates this technique also for follow-up of AS.
Keywords: 18F-fluoride PET; ASDAS; Ankylosing spondylitis; BASDAI; BASFI; Spondyloarthritis.