LOW PERCENTAGE OF MRI CHANGES IN CLINICALLY SUSPECTED AXIAL SPONDYLOARTHRITIS

Background The prevalence of Ankylosing Spondylitis (AS) reaches about 0.9%, starts at a relatively young age and the burden of the disease is considerable. A diagnostic algorithm was developed in order to detect the disease at an early stage, the so called non-radiographic Axial Spondyloarthritis (SpA) (ref). MRI techniques play an important role in this diagnosis in the absence of radiographic sacroiliitis and was propagated as a diagnostic tool. Objectives to study the prevalence of inflammatory changes on MRI of pelvis and spine in patients who are clinically suspected to have of non-radiographic axial SpA. Methods Patients above 18 years of age with inflammatory back pain, during at least 3 months with onset below the age of 45 years, were included in case of presence of at least 2 Spondylarhropathy features or at least one Spa feature and either presence of HLA-B27 antigen or at least two family members with definite AS. MRI of the pelvis and spine (T1, T2 and STIR) was performed and repeated after 16 weeks if no signs of inflammation were present the first time. Patients who fulfilled the modified New York criteria for AS were excluded. Results 55 candidates were screened, of whom 9 were excluded because they fulfilled the New York criteria of AS already. The MRI results of the remaining 46 patients are: 13 showed signs of inflammation (28%), 12 had a negative MRI once (26%) and 21 had a negative MRI at two time periods (46%). Five out of the 12 patients who had a negative MRI refused to have another MRI because of several reasons, mostly because they were afraid to enter the narrow tunnel again despite premedication. Therefore, out of 46 eligible patients, 33 (71%) showed a negative MRI at least once despite the fact that they fulfilled the clinical algorithm of axial SpA. Conclusions In patients who were clinically suspected to have non-radiographic axial Spondyloarthritis, only 29% showed signs of inflammation at the MRI of the sacroiliac joints and or spine at one time point. Therefore, the sensitivity for MRI as a useful tool to establish the diagnosis non radiographic axial SpA seems to be limited. References Rudwaleit M, van der HD, Khan MA, Braun J, Sieper J. How to diagnose axial spondyloarthritis early. Ann Rheum Dis 2004; 63(5):535-543. Disclosure of Interest I. Van Der Horst-Bruinsma Grant/Research support from: Pfizer, M. van der Weijden: None Declared, S. Bruijnen: None Declared, S. Weismann: None Declared, P. Bet: None Declared, C. van Kuijk: None Declared, J. Twisk: None Declared, B. Dijkmans: None Declared, C. van der Laken: None Declared, M. Nurmohamed: None Declared