THU0393 Increased 18F-Fluoride Uptake Lesions at Vertebral Corners on Positron Emission Tomography Predict New Syndesmophytes Development in Ankylosing Spondylitis
Authors: E.-K. Park, S.-G. Lee, D.-W. Koo, J.-H. Park, G.-T. Kim, H.-S. Tag, J.-W. Lee
Journal: Annals of the Rheumatic Diseases (2016)

<h3>Background</h3> 18F-fluoride uptake on positron emission tomography (PET) represents osteoblastic activity. Previous cross-sectional studies showed that increased 18F-fluoride uptake lesions at vertebral corners were associated with both inflammation and structural changes on magnetic resonance imaging (MRI) and radiography, respectively, in patients with ankylosing spondylitis (AS) <sup>1,2</sup>. But, longitudinal studies that investigated the association between increased 18F-fluoride uptake lesions and future syndesmophytes formation are lacking. <h3>Objectives</h3> We aimed to demonstrate that increased 18F-fluoride uptake lesions on PET predict the development of new syndesmophytes. <h3>Methods</h3> In 12 patients with AS, 18F-fluoride PET-MRI (Philips Healthcare, Cleveland, OH, USA) was performed at baseline and radiography was performed at baseline and 2 years. We recorded 18F-fluoride uptake lesions on PET, acute (type A) and advanced (type B) corner inflammatory lesions (CILs) and fat lesions on MRI and syndesmophytes on radiography. An increased 18F-fluoride uptake lesion was defined as an uptake greater than the uptake in the adjacent normal vertebral body (Figure 1). <h3>Results</h3> Of 231 anterior vertebral corners without syndesmophyte at baseline, 13 type A CILs (5.5%), 2 type B CILs (0.9%) and 20 fat lesions (8.7%) on MRI and 6 increased fluoride uptake lesions (2.6%) on PET were observed. After 2 years, 16 new syndesmophytes (6.9%) in 8 AS patients (66.7%) occurred. New syndesmophytes developed significantly more frequently in anterior vertebral corners with increased 18F-fluoride uptake lesions (50%) or fat lesions (25%) at baseline, as compared with those without either feature (5.8% and 5.2%, respectively). In generalised linear latent mixed models after adjusting within-patient correlation, baseline increased 18F-fluoride uptake lesion significantly predicted the development of new syndesmophytes (OR=20.6, 95% CI=2.7–156.1, p=0.003). Fat lesions were also associated with new syndesmophytes development (OR=9.3, 95% CI=2.1–40.2, p=0.003), but this association was not observed in CILs. <h3>Conclusions</h3> Our findings indicate that increased 18F-fluoride uptake lesions can predict future new syndesmophytes formation in patients with AS. 18F-fluoride PET may be used to estimate structural damage in these patients. <h3>References</h3> Lee SG et al. Assessment of bone synthetic activity in inflammatory lesions and syndesmophytes in patients with ankylosing spondylitis: the potential role of 18F-fluoride positron emission tomography-magnetic resonance imaging. Clin Exp Rheumatol 2015;33:90–7. Buchbender C et al. Hybrid 18F-labeled Fluoride Positron Emission Tomography/Magnetic Resonance (MR) Imaging of the Sacroiliac Joints and the Spine in Patients with Axial Spondyloarthritis: A Pilot Study Exploring the Link of MR Bone Pathologies and Increased Osteoblastic Activity. J Rheumatol 2015;42:1631–7. <h3>Disclosure of Interest</h3> None declared