LAUSR

Background In clinical trials radiographic damage is frequently quantified by conventional x-ray but neither the thoracic spine nor the posterior parts of the vertebral column including the intervertebral joints, the vertebral arch and the spinous process can be evaluated reliably with this instrument. Bone inflammation and areas of enthesitis can easily be detected by magnetic tomography imaging (MRI) and the introduction of high-resolution 3-tesla MRI allows analysis of bone structures more precisely than with x-ray without radiation exposure [1]. Patients with axial SpA frequently present with reduced spinal mobility and functional impairment, but radiographic signs of ankylosis are missing on plain radiographs. These particular clinical findings are reinforced by data in the literature showing, that the relation between radiographic damage, spinal mobility and function is low. Radiographic damage to the posterior parts of the vertebral column may be responsible for the discrepancy found between clinical and radiographic results as suggested by a Dutch group [2]. Objectives To evaluate the localisation and incidence of new bone formation in the posterior part of the vertebral bodies with MRI. Methods In a cohort of 56 patients with diagnosed axial SpA (mean age 50.29y, mean disease duration 14.4y, 76.4% men, 88.7% HLA-B27 positive) we performed a MRI (3 Tesla scanner Skyra, Siemens Healthcare, Erlangen, Germany). The whole spine was scanned with T1 weighted and Turbo-Inversion Recovery Magnitude (TIRM) sequences in sagittal planes and each segment of the vertebral column was divided into four areas (ventral and posterior part of the vertebral bodies, intervertebral joints andspinous processes) to assess osseous changes like sclerosis, erosion, syndesmophytes, ankylosis, (partial) fusion of intervertebral joints and fibroostosis of spinous processes. Results Syndesmophytes and ankylosis of the ventral segments were present from C7/Th1 down to L5/S1 with a maximum in Th5/6 (62.5%). In the posterior segments of the vertebral bodies we detected a contrary accumulation inside the cervical and lumbar spine with a max. in C5/6 (55.4%) respectively L2/3 (66.1%). Erosions were mainly found at the ventral edges with an accumulation in middle cervical, lower thoracic and the whole lumbar spine (max. Th9/10 24.5%) Ankylosis of the intervertebral joints was present over the whole spine with a preference of the cervical (max. C5/6 27.7%) and lumbar column (max. L2/3 47.3%). Fibroostosis of the spinous processeswere rarely found in the middle and lower thoracic spine (Th5-11, each 2.7%). In up to 57.10% of the cervical spine (54.78% for lumbar, 32.18% for thoracic spine) with detectable new bone formation of the posterior segments we found no changes of the ventral part. Conclusion With high resolution MRI we were able to detect structural in the dorsal part of the spine, which can hardly be assessed by conventional radiographs. These findings may explain functional disability in patients with non-corresponding findings in x-ray. References [1] Lee CH, et al. (2015) Correlation of structural abnormalities of the wrist and metacarpophalangeal joints evaluated by high-resolution peripheral quantitative computed tomography, 3 Tesla magnetic resonance imaging and conventional radiographs in rheumatoid arthritis. International journal of rheumatic diseases [2] Maas F, et al. (2015) Comparison of radiographic damage of the zygapophyseal joints and the vertebral bodies of the cervical spine in patients with ankylosing spondylitis before and after 4 years of TNF-alpha blocking therapy. Annals of the rheumatic diseases Disclosure of Interests Andreas Haidmayer Speakers bureau: Roche, MSD, BMS, Abbvie, Celgene, Gabriel Adelsmayr Speakers bureau: BMS, Rusmir Husic Speakers bureau: BMS, UCB, Celgene, MSD, Franz Quehenberger: None declared, Angelika Lackner: None declared, Joesf Hermann Speakers bureau: Abbvie, MSD, UCB, BMS, Celgene