ACR 2017 | Daily Highlights
A Positive MRI of the Sacroiliac Joints Is Not Specific for Axial Spondyloarthritis but Frequently Occurs in Healthy Individuals
Authors: Janneke de Winter1, Manouk de Hooge2, Marleen van de Sande1, Lonneke van Hoeven3, Jet de Jong1, Anoek de Koning2, Inger Jorid Berg4, Roberta Ramonda5, Dominique Baeten1,6, Désirée van der Heijde7, Angelique Weel8 and Robert B.M. Landewé9, 1Clinical Immunology and Rheumatology, Amsterdam Rheumatology and immunology Center, Academic Medical Center/University of Amsterdam, Amsterdam, Netherlands, 2Rheumatology, Leiden University Medical Center, Leiden, Netherlands, 3Rheumatology, Maasstad Hospital, Rotterdam, Netherlands, 4Rheumatology, Diakonhjemmet Hospital, Oslo, Norway, 5Rheumatology Unit, Department of Medicine DIMED, University of Padova, Padova, Italy, 6UCB Pharma, Slough, United Kingdom, 7Leiden University Medical Center, Leiden, Netherlands, 8Department of Rheumatology, Maasstad Hospital, Rotterdam, Netherlands, 9Amsterdam Rheumatology & Immunology Center, Academic Medical Center, Amsterdam, Netherlands
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 ? 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.
J. de Winter, None; M. de Hooge, None; M. van de Sande, Takeda, Tillots, MSD, Abbvie,novartis, boeringer ingelheim, 5,Takeda, Tillots, MSD, Abbvie,novartis, boeringer ingelheim, 8,Takeda, Tillots, MSD, Abbvie,novartis, boeringer ingelheim, 5; L. van Hoeven, None; J. de Jong, None; A. de Koning, None; I. J. Berg, None; R. Ramonda, None; D. Baeten, UCB, 3; D. van der Heijde, AbbVie, Amgen, Astellas, AstraZeneca, BMS, Boehringer Ingelheim, Celgene, Daiichi, Eli-Lilly, Galapagos, Gilead, Glaxo-Smith-Kline, Janssen, Merck, Novartis, Pfizer, Regeneron, Roche, Sanofi, Takeda, UCB, 5,Imaging Rheumatology bv., 9; A. Weel, None; R. B. M. Landewé, ASAS, 9.
Data on the specificity of bone marrow edema for axial spondyloarthritis (axSpA) is scarce. While osteitis condensans ilii has been seen as a major differential diagnosis in patients with back pain (see abstract 1510), the current study indicates that a positive MRI of the sacroiliac joints according to the ASAS definition might be demonstrated in about 20% of healthy individuals, 13% of runners and up to 60% of women with postpartum back pain. Extensive bone marrow edema is, however, only seen in patients with sacroiliitis due to axSpA.
PD Dr. Adrian Ciurea