• 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.

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.

Reproducibility of radiographic SIJ classification in an SpA inception cohort was only fair to at best moderate among 7 readers with varying levels of experience, questioning the applicability of mNY in early SpA.

BackgroundThe aim of this study was to investigate subgroups of magnetic resonance imaging (MRI) findings for the spine and sacroiliac joints (SIJs) using latent class analysis (LCA), and to investigate whether these subgroups differ in their demographic and clinical characteristics.MethodsThe sample included 1037 patients aged 18–40 years with persistent low back pain (LBP). LCA was applied to MRI findings of the spine and SIJs. The resulting subgroups were tested for differences in self-reported demographic and clinical characteristics.ResultsA five-class model was identified: Subgroup 1, ‘No or few findings’ (n = 116); Subgroup 2, ‘Mild spinal degeneration’ (n = 540); Subgroup 3, ‘Moderate to severe spinal degeneration’ (n = 229); Subgroup 4, ‘Moderate to severe spinal degeneration with mild SIJ findings’ (n = 68); and Subgroup 5, ‘Mild spinal degeneration with moderate to severe SIJ findings’ (n = 84). The two SIJ subgroups (Subgroups 4 and 5) had a higher median activity limitation score (Roland Morris Disability Questionnaire calculated as a proportional score: 65 (IQR 48–78)/65 (48–78)) compared with Subgroups 1–3 (48 (35–74)/57 (39–74)/57 (39–74)), a higher prevalence of women (68 % (95 % CI 56–79)/68 % (58–78)) compared with Subgroups 2 and 3 (51 % (47–55)/40 % (33–46)), a higher prevalence of being overweight (67 % (95 % CI 55–79)/53 % (41–65)) compared with Subgroup 1 (36 % (26–46)) and a higher prevalence of previous LBP episodes (yes/no: 81 % (95 % CI 71–91)/79 % (70–89)) compared with Subgroup 1 (58 % (48–67)). Subgroup 5 was younger than Subgroup 4 (median age 29 years (IQR 25–33) versus 34 years (30–37)) and had a higher prevalence of HLA-B27 (40 % (95 % CI 29–50)) compared with the other subgroups (Subgroups 1–4: 12 % (6–18)/7 % (5–10)/6 % (3–9)/12 % (4–20)). Across the subgroups with predominantly spinal findings (Subgroups 1–3), median age, prevalence of men, being overweight and previous LBP episodes were statistically significantly lower in Subgroup 1, higher in Subgroup 2 and highest in Subgroup 3.ConclusionsFive distinct subgroups of MRI findings in the spine and SIJs were identified. The results indicate that SIJ MRI findings not only can be seen as a part of the spondyloarthritis disease entity, but also are associated with age, gender and being overweight. Furthermore, the results indicate that LBP patients with SIJ MRI findings are more disabled compared with patients without SIJ MRI findings, and that moderate to severe spinal degeneration and/or SIJ MRI findings may be associated with recurrent pain.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-016-1131-x) contains supplementary material, which is available to authorized users.

The identified associations between inflammatory MRI findings and pain characteristics indicate that axial inflammation to some degree induces a specific pain pattern. Thus, the results add to knowledge of axial inflammatory processes. However, all identified associations were weak, which compromises the use of IBP as a marker of axial inflammation.

IntroductionMagnetic resonance imaging (MRI) has been proven capable of showing inflammatory and structural changes in patients with spondyloarthritis (SpA) and has become widely used in the diagnosis of SpA. Despite this, no systematic reviews evaluate the diagnostic utility of MRI for SpA. Therefore, the objective of this systematic review was to determine the evidence for the utility of MRI in the clinical diagnosis of SpA. The aims were to identify which MRI findings are associated with the diagnosis of SpA and to quantify this association.MethodsMEDLINE and EMBASE were electronically searched. Inclusion criteria were cross-sectional or longitudinal case-control or cohort MRI studies. The studies required a group with either SpA or inflammatory back pain (IBP) and a non-case group without SpA or IBP. Each group required a minimum of 20 participants. The included articles had to report results containing raw numbers suitable for the construction of two-by-two tables or report results by sensitivity and specificity for cross-sectional studies or odds ratios, relative risk ratios, or likelihood ratios for longitudinal studies. Method quality was assessed by using criteria based on the QUADAS tool.ResultsIn total, 2,395 articles were identified in MEDLINE and EMBASE before November 2011. All articles were reviewed by title and abstract. Seventy-seven articles were reviewed by full text, and 10 met the inclusion criteria. Two were considered of high quality: one evaluated the sacroiliac joints, and the other, the spine. Because of the small number of high-quality studies, a meta-analysis was not performed. The two high-quality studies found a positive association between MRI findings (bone marrow edema, erosions, fat infiltrations, global assessment of sacroiliitis, and ankylosis) and the diagnosis of IBP and SpA.ConclusionIn this review, several MRI findings were found to be associated with SpA. However, because of the small number of high-quality studies, the evidence for the utility of MRI in the diagnosis of SpA must be considered limited. Therefore, caution should be taken to ensure that inflammatory and structural MRI findings are not interpreted as being more specific for SpA than is supported by research.

Only in men were the SI joint tests found to be associated with sacroiliitis identified by MRI. Although, the diagnostic value was relatively low, the results indicate that the use of SI joint tests for sacroiliitis may be optimized by gender-separate analyses.