In which patients with inflammatory back pain, does it make sense to repeat magnetic resonance scanning of the spine?
• Repeating magnetic resonance scanning of the spine in patients with inflammatory back pain who have a primary negative scan may diagnose new axial spondyloarthritis, especially in HLA-B27-positive males.
• Repeat MRI in patients with inflammatory back pain does not appear to be useful in diagnosing new axial spondyloarthritis in women or HLA-B27 negative patients.
Radiographic sacroiliitis is required to make the diagnosis of spondyloarthritis. Sengupta and fellow researchers1 in the United Kingdom point out that radiographic progression may be slow and as such may lead to delays in diagnosis and subsequent treatment.
While MRI of the spine may be able to detect inflammatory disease early, its sensitivity is limited because more than one-third of patients with active axial spondyloarthritis have no inflammatory lesions when scanned. The researchers point out that the optimal timing for MRI in suspected spondyloarthritis is poorly defined.
The researchers sought to evaluate clinically suspected axial spondyloarthritis with MRI over a 12-week period. They recently presented their findings in the Journal of Rheumatology.1
The authors performed a prospective cohort study, recruiting patients in the United Kingdom with inflammatory back pain based on the Assessment of Spondyloarthritis International Society (ASAS) criteria and normal sacroiliac joint radiographs. MRI was performed at intervals of 4, 8, and 12 weeks to assess for inflammatory evidence of spondyloarthritis. Ultimately, 29 patients were included in the study analysis.
• Prior to imaging, 59% of subjects met clinical criteria for axial spondyloarthritis.
• 38% of subjects met the ASAS imaging criteria during the study with an additional 10% having positive MRI scans of the spine but normal sacroiliac joints.
• 52% of subjects met ASAS criteria for axial spondyloarthritis and had negative MRI scans at baseline and throughout the study.
• 34% of subjects were positive for spine and/or sacroiliac joint criteria for the entire study.
• Only 14% of subjects changed from ASAS negative (MRI negative) to positive during the study, which influenced their final diagnosis.
• 89% of subjects started the study with normal C reactive protein levels (CRP).
• 20% of subjects who started with normal CRP levels developed elevated levels during the study.
• 100% of subjects whose MRI scans changed from negative to positive were HLA-B27-positive, and 75% of them were male.
Implications for physicians
• Consider repeating MRI scans in male patients with inflammatory back pain if previous scans are negative, especially if those patients are HLA-B27 positive.
• The decision to repeat scans should take into consideration cost, clinical correlation (symptoms), and treatment options, since this evidence is derived from a small sample with no control groups.
• It does not appear that repeating MRI scans in women or HLA-B27-negative patients is useful.
No sources of funding were reported.
1. Sengupta R, Marzo-Ortega H, McGonagle D, et al. Short-term magnetic resonance imaging scans in suspected early axial spondyloarthritis are clinically relevant only in HLA-B27-positive male subjects. J Rheumatol. 2018;45:2. doi: 10.3899/jrheum.170171.