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Patients with chronic back pain of short duration from the SPACE cohort: which MRI structural lesions in the sacroiliac joints and inflammatory and structural lesions in the spine are most specific for axial spondyloarthritis?
  1. Manouk de Hooge1,
  2. Rosaline van den Berg1,
  3. Victoria Navarro-Compán1,2,
  4. Monique Reijnierse3,
  5. Floris van Gaalen1,
  6. Karen Fagerli4,
  7. Robert Landewé5,
  8. Maikel van Oosterhout6,
  9. Roberta Ramonda7,
  10. Tom Huizinga1,
  11. Désirée van der Heijde1
  1. 1Rheumatology Department, Leiden University Medical Center, Leiden, The Netherlands
  2. 2Rheumatology Department, University Hospital La Paz, Madrid, Spain
  3. 3Radiology Department, Leiden University Medical Center, Leiden, The Netherlands
  4. 4Rheumatology Department, Diakonhjemmet Hospital, Oslo, Norway
  5. 5Department of Clinical Immunology and Rheumatology, Amsterdam Medical Center, Amsterdam, The Netherlands
  6. 6Rheumatology Department, Groene Hart Ziekenhuis, Gouda, The Netherlands
  7. 7Rheumatology Unit, University of Padova, Padova, Italy
  1. Correspondence to Professor Désirée van der Heijde, Leiden University Medical Center, P.O. Box 9600, Leiden 2300 RC, The Netherlands; mail{at}


Objectives To investigate the extent and performance of MRI lesions in the sacroiliac joint (MRI-SI) and spine (MRI-spine) in patients with suspected axial spondyloarthritis (axSpA).

Methods MRI-SI/spine of patients with chronic back pain (onset <45 years) in the SPondyloArthritis Caught Early (SPACE) cohort were scored by two well-trained readers for inflammation, fatty lesions, erosions, sclerosis/ankylosis and syndesmophytes. MRI performances were tested against the Assessment of Spondyloarthritis international Society (ASAS) axSpA criteria (positive: imaging-arm+ or clinical-arm+; negative: possible axSpA (few spondyloarthritis (SpA) features present) or no SpA). Arbitrary cut-off levels for MRI lesions were set to assure at least 95% specificity (tested in the no SpA group).

Results In total 126 patients were ASAS criteria positive (73 imaging-arm+ (22 by modified New York criteria (mNY)+; 51 by MRI+mNY−); 53 clinical-arm+) and 161 were ASAS criteria negative (89 possible axSpA and 72 no SpA). On MRI-SI (n=287), at least three fatty lesions (or at least three erosions) were seen in 45.5 (63.6)% of mNY+ patients, 15.7 (47.1)% of MRI+mNY− patients and 15.1 (13.2)% of clinical-arm+ patients versus 3.4 (6.7)% of possible axSpA patients and 2.8 (4.2)% of no SpA patients. A combined rule (at least five fatty lesions and/or erosions) performed equally well. Sclerosis and ankylosis were too rare to analyse. On MRI-spine (n=284), at least five inflammatory lesions (or at least five fatty lesions) were seen in 27.3 (18.2)% of mNY+ patients, 13.7 (21.6)% of MRI+mNY− patients and 3.8 (1.9)% of clinical-arm+ patients versus 4.5 (6.7)% of possible SpA patients and 2.9 (4.3)% of no SpA patients.

Conclusions The presence of (1) at least five fatty lesions and/or erosions on MRI-SI, (2) at least five inflammatory lesions or (3) at least five fatty lesions on MRI-spine allows an acceptable discrimination of axSpA and no SpA, while assuring >95% specificity.

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