• The location of vertebral endplate signal changes supports a mechanical aetiology. • Several sacroiliac joint findings were associated with female gender and pregnancy-related back pain. • Sacroiliac joint bone marrow oedema was frequent and age-associated, indicating a possible degenerative aetiology. • More knowledge of the clinical importance of sacroiliac joint MRI findings is needed.

Objective. The Assessment of SpondyloArthritis international Society (ASAS) has previously published criteria for spondyloarthritis (SpA). In the Spines of Southern Denmark cohort, which included patients with persistent low back pain and an unknown proportion of patients with SpA, our objectives were 1) to estimate the prevalence of magnetic resonance imaging (MRI) findings and clinical features included in the ASAS criteria for SpA and 2) to explore the associations between MRI findings and clinical features.Methods. We included patients ages 18-40 years with persistent low back pain who had been referred to the Spine Centre of Southern Denmark. We collected information on clinical features (including HLA-B27 and high-sensitivity C-reactive protein) and MRI findings in the spine and sacroiliac (SI) joints.Results. Of 1,020 included patients, 537 (53%) had at least 1 of the clinical features included in the ASAS criteria for SpA. Three clinical features were common-inflammatory back pain according to the ASAS criteria, a good response to nonsteroidal antiinflammatory drugs (NSAIDs), and family history of SpA. The prevalence of these features ranged from 15% to 17%. Sacroiliitis on MRI according to the ASAS definition was present in 217 patients (21%). Of those 217 patients, 91 (42%) had the minimum amount of bone marrow edema required according to the ASAS definition (a low bone marrow edema score). The presence of HLA-B27, peripheral arthritis, a good response to NSAIDs, and preceding infection were independently positively associated with MRI findings in the SI joints (odds ratios [ORs] of 1.9-9.0). The remaining 8 clinical features were not positively associated with MRI findings. Importantly, only age was independently associated with low bone marrow edema score at the SI joints (OR of 1.1 per year).Conclusion. In this population, 53% had at least 1 clinical feature included in the ASAS criteria for SpA, and 21% had sacroiliitis according to the ASAS definition; furthermore, the associations between the clinical and imaging domains were inconsistent. The results indicate a need for further investigation of the importance of these findings in SpA, including investigation of the minimum requirements for defining sacroiliitis on MRI.

In recreational and elite athletes, MRI revealed BME in an average of 3-4 SI joint quadrants, meeting the ASAS definition of active sacroiliitis in 30-41% of subjects. The posterior lower ilium was the single most affected SI joint region. These findings in athletes could help refine data-driven thresholds for defining sacroiliitis in early SpA.

IntroductionInflammatory involvement of the anterior chest wall (ACW) affects the quality of life of patients with spondyloarthritis (SpA), although involvement of the ACW is often neglected on clinical and imaging evaluation. Whole-body (WB) MRI is an imaging method used to assess the ACW in addition to the sacroiliac joints and spine without inconvenience for patients. Our goals in this study were to describe the distribution of ACW inflammation by WB MRI in both early and established SpA and associations between clinical and imaging findings indicative of inflammation.MethodsThe ACWs of 122 consecutive SpA patients (95 with ankylosing spondylitis (AS) and 27 with nonradiographic SpA (nrSpA)) and 75 healthy controls were scanned by sagittal and coronal WB MRI. The MRI scans were scored independently in random order by seven readers blinded to patient identifiers. Active and structural inflammatory lesions of the ACW were recorded on a web-based data entry form. ACW pain by patient self-report, ACW tenderness on physical examination according to the Maastricht Ankylosing Spondylitis Enthesitis Score (MASES) and lesions detected by MRI were analyzed descriptively. κ statistics served to assess the agreement between clinical and imaging findings.ResultsACW pain or tenderness was present in 26% of patients, with little difference between AS and nrSpA patients. Bone marrow edema (BME), erosion and fat infiltration were recorded in 44.3%, 34.4% and 27.0% of SpA patients and in 9.3%, 12.0% and 5.3% of controls, respectively. Lesions found by MRI occurred more frequently in AS patients (BME, erosion and fat infiltration in 49.5%, 36.8% and 33.7%, respectively) than in nrSpA patients (25.9%, 25.9% and 3.7%, respectively). The joint most frequently affected by lesions found on MRI scans was the manubriosternal joint. The κ values between clinical assessments and MRI inflammation ranged from -0.10 to only 0.33 for both AS and nrSpA patients.ConclusionsAmong SpA patients, 26% had clinical involvement of the ACW. WB MRI signs of ACW inflammation were found in a substantial proportion of patients with AS (49.5%) and nrSpA (25.9%). There was no association between clinical assessments of ACW, including the MASES, and MRI features.

BackgroundThe Back Pain Cohort of Southern Denmark (BaPa Cohort) was initiated with the aim of evaluating the clinical relevance of magnetic resonance imaging (MRI) in the diagnosis of early spondyloarthritis (SpA). In order to facilitate the collection of MRI data for this study, an electronic evaluation form was developed including both SpA-related and degenerative axial changes. The objective of the current study was to assess the intra- and inter-observer agreement of the MRI changes assessed.MethodsThree radiologists evaluated 48 MRI scans of the whole spine and the sacroiliac joints from a subsample of the BaPa Cohort, consisting of patients with non-specific low back pain and patients with different stages of SpA features. The spine was evaluated for SpA-related and degenerative MRI changes and the SIJ for SpA-related changes. Inter- and intra-observer agreements were calculated with kappa statistics. In the interpretation of the kappa coefficient, the standards for strength of agreement reported by Landis and Koch were followed.ResultsA total of 48 patients, 40% men and mean age of 31 years (range 18 – 40 years), were evaluated once by all three readers and re-evaluated by two of the readers after 4-12 weeks. For MRI changes in the spine, substantial to almost perfect observer agreement was found for the location and the size of vertebral signal changes and for disc degeneration and disc contour. For the sacroiliac joints, substantial or almost perfect observer agreement was found for the grading of bone marrow oedema and fatty marrow deposition, the depth of bone marrow oedema and for subchondral sclerosis. Global assessment of the SpA diagnosis had substantial to almost perfect observer agreements.ConclusionThe acceptable agreement for key MRI changes in the spine and sacroiliac joints makes it possible to use these MRI changes in the BaPa Cohort study and other studies investigating MRI changes in patients with non-specific low back pain and suspected SpA.