Date: Monday, November 6, 2017
Session Type: ACR Concurrent Abstract Session
Session Time: 2:30PM-4:00PM
Inflammation shown on MRI of the sacroiliac joint (MRI-SI) is prevalent in axSpA (±30%) but the specificity is not well known, hence we compared MRI-SI of healthy individuals and those with known mechanical strain acting upon SIJ.
Three trained, blinded readers randomly scored MRI-SI of 172 subjects: 47 healthy individuals (1); 47 age- and gender-matched axSpA patients (with a confirmed positive MRI by central readers) from the SPondyloArthritis Caught Early (SPACE) cohort; 47 age- and gender-matched CBP patients (irrespective of MRI results) from the SPACE cohort; 7 women with postpartum back pain; and 24 frequent runners. The readers scored MRIs according to the ASAS/OMERACT and SPARCC definitions. MRIs were considered positive when at least two of the three readers agreed. SPARCC scores are the mean SPARCC scores of all three readers.
The three reader pairs agreed in 75.6-79.9% of the cases on the presence/absence of BME (Cohen’s κ 0.48-0.59), SPARCC scores correlated well (ICCs 0.824-0.964). Of the healthy volunteers, 11 out of 47 (23.4%) had a positive MRI-SI, compared to 43 out of 47 (91.5%) of the positive axSpA patients and 3 out of 47 (6.4%) CBP patients. Of the runners, 3 out of 24 (12.5%) -and of the women with postpartum back pain 4 out of 7 (57.1%)- had a positive MRI-SI. The mean (SD) SPARCC scores were 1.7 (2.4) (healthy individuals), 20.9 (13.7) (positive axSpA patients), 0.8 (1.4) (CBP patients), 0.8 (1.1) (frequent runners) and 4.5 (6.3) (postpartum patients) (Figure 1). When a SPARCC score ≥2 was used as a cut-off for positivity, 12 out of 47 healthy volunteers (25.5%), 46 out of 47 positive axSpA patients (97.9%), 5 out of 47 CBP patients (10.6%), 4 out of 24 runners (16.7%) and 4 out of 7 women with postpartum back pain (57.1%) were declared positive. When a SPARCC score ≥5 was used as a cut-off score, these figures were 4 out of 47 healthy volunteers (8.5%), 41 out of 47 positive axSpA patients (87.2%), 1 out of 47 CBP patients (2.1%), 0 out of 24 runners and 2 out of 7 women with postpartum back pain (28.6%). ‘Deep’ BME-lesions (increase in signal ≥1 cm from the articular surface) were not found in healthy volunteers, CBP patients and runners, but in 38 out of the 47 positive axSpA patients (80.9%) and in one out of 7 women with postpartum back pain (14.3%).
A substantial proportion of healthy individuals has a positive MRI-SI according to the ASAS/OMERACT definition. High SPARCC scores (≥5) rarely occur in healthy individuals, CBP patients and runners. ‘Deep’ (extensive) lesions seem exclusive of sacroiliitis in axSpA patients.
Figure 1. Percentage of positive MRI-SI and total SPARCC scores, each dot represents one individual.
1. van Hoeven L, Luime JJ et al.Bone marrow edema and structural lesions in the sacroiliac joint in a large cohort of patients with axial spondyloarthritis, chronic low back pain and healthy controls. ACR Annu Meet. 2013;2889.
To cite this abstract in AMA style:de Winter J, de Hooge M, van de Sande M, van Hoeven L, de Jong J, de Koning A, Berg IJ, Ramonda R, Baeten D, van der Heijde D, Weel A, Landewé RBM. A Positive MRI of the Sacroiliac Joints Is Not Specific for Axial Spondyloarthritis but Frequently Occurs in Healthy Individuals [abstract]. Arthritis Rheumatol. 2017; 69 (suppl 10). https://acrabstracts.org/abstract/a-positive-mri-of-the-sacroiliac-joints-is-not-specific-for-axial-spondyloarthritis-but-frequently-occurs-in-healthy-individuals/. Accessed September 20, 2021.
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