Background Axial spondyloarthritis (AxSpA) is a chronic inflammatory condition predominantly involving the axial skeleton including the spine and sacroiliac joints. Magnetic resonance imaging (MRI) demonstrates inflammatory and structural changes in patients with both ankylosing spondylitis and non-radiographic (nrAxSpA) forms of SpA and has become widely used in diagnosing SpA.
Sacroiliitis is a prominent feature of SpA but up to 24% of patients with clinically active SpA can have normal MRI of their sacroiliac joints (SIJ).1 Spinal inflammation is well recognized in SpA and studies have shown that 49% of clinically active nr-AxSpA patients have spinal lesions alone but no lesions in SIJ.2 Thoracic spinal lesions are as common as SIJ lesions.3 Therefore using spinal in addition to SIJ MRI should improve the overall sensitivity and specificity for the detection of the disease.
Prior to publication of the 2015 EULAR recommendations,4 an evidence-based MRI protocol had been adopted in our hospital, using STIR and T1-weighted sequences of the whole spine and SIJs in patients with suspected SpA.
Objectives To determine the additional diagnostic benefit of including limited sequence whole spine imaging with SIJ MRI to SIJ MRI alone in patients with suspected SpA.
Methods MRI scans performed for suspected SpA over twelve months from November 2015 to November 2016 were reviewed retrospectively (n=203). Reports were analysed for presence and location of lesions suggestive of SpA. HLA-B27 status of the patients and the presence of SpA associated clinical features as defined by ASAS criteria were recorded.
Results MRI scans from 203 patients with suspected SpA were reviewed. 81 (40%) were male and 122 (60%) were female. The age range was 13 to 78 years (mean =41). 130 (64%) were less than 45 years of age. 157/203 (77%) patients had been tested for HLA B-27 alleles of whom 46 (29%) were HLA-B27 positive. All patients had inflammatory back pain and 76 (37%) had one or more additional SpA features as per ASAS criteria.
Overall 43 (21%) patients had a positive MRI spine and/or SIJs for inflammatory or structural changes. 21/43 (49%) patients had inflammatory lesions in their sacroiliac joints only. 18/43 (42%) patients had inflammatory changes involving both SIJ and Spine and 4/43 (9%) had spinal inflammatory changes only with normal SIJs (Table 1). In these four patients the thoraco-lumbar spine was involved. In HLA-B27 positive patients (n=46), 25 (54%) had a positive MRI.
Conclusions The majority of patients with SpA can have their diagnosis confirmed on SIJ MRI. However a proportion of patients (9%) had spinal changes only. Additional spinal MRI has been shown to increase the diagnostic yield for axial spondyloarthropathy in our cohort.
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Disclosure of Interest None declared