Assessing structural changes in axial spondyloarthritis using a low-dose biplanar imaging system

Rheumatology (Oxford). 2014 Sep;53(9):1669-75. doi: 10.1093/rheumatology/keu143. Epub 2014 Apr 15.


Objectives: Patients with axial SpA experience repeated spine imaging. EOS is a new low-dose imaging system with significantly lower irradiation than conventional radiography (CR). The objective was to explore the EOS performances compared with CR for the classification and follow-up of SpA.

Methods: We performed an observational, cross-sectional, single-centre study including SpA patients (definite diagnosis by expert opinion) and control patients [definite chronic mechanical low back pain (cLBP)]. All patients underwent pelvic and frontal and lateral CR of the entire spine and two-dimensional (2D) EOS imaging on the same day. Images were blindly assessed for sacroiliitis [modified New York criteria (mNY)] and for ankylosis of the spine [modified Stoke AS Spine Score (mSASSS)]. Global ease of interpretation was rated on a scale of 0-10. The primary outcome was intermodality agreement, with an a priori defined non-inferiority limit of 0.7. Interobserver, intra-observer and intermodality agreement were measured by kappa, weighted kappa, intraclass correlation coefficient and Bland-Altman plots.

Results: Forty-eight SpA patients [mean age 47.6 years (s.d. 14.9), symptom duration 21.4 years (s.d. 13.3), 35 (70%) men] and 48 cLBP controls [mean age 49.1 years (s.d. 10.7), 9 (22.5%) men] were included. Intermodality agreement between EOS and CR was 0.50 (95% CI 0.26, 0.75) and 0.97 (95% CI 0.95, 0.98) for sacroiliitis and mSASSS, respectively. Ease of interpretation was greater for CR [8.2 (s.d. 0.9)] compared with EOS [7.2 (s.d. 0.8), P < 0.0001).

Conclusion: Our results suggest that EOS could replace CR for the follow-up of structural damage of the spine, but its place in the classification of sacroiliitis needs to be further explored.

Keywords: EOS; ankylosis; radiography; sacroiliitis; spondyloarthritis; syndesmophytes.

Publication types

  • Observational Study

MeSH terms

  • Adult
  • Cross-Sectional Studies
  • Female
  • Humans
  • Low Back Pain / diagnostic imaging
  • Male
  • Middle Aged
  • Observer Variation
  • Radiation Dosage
  • Radiographic Image Interpretation, Computer-Assisted / methods
  • Reproducibility of Results
  • Sacroiliac Joint / diagnostic imaging
  • Sacroiliitis / diagnostic imaging
  • Severity of Illness Index
  • Spondylarthritis / diagnostic imaging*