MRI Activity Scores & SpA

Hon Wai Lau,1 Chi Chiu Mok,2 Wun Cheung Samuel Chan,1 Ming Keung Yuen,1 On Chee Li1

1Department of Radiology, 2Department of Medicine, Tuen Mun Hospital, Tuen Mun, New Territories, Hong Kong

Objective: To analyze the correlation between the magnetic resonance imaging (MRI) disease activity scores and the clinical disease activity indices (DAI) in Chinese patients with active axial spondyloarthritis (aSpA) that required biologics therapy. The correlation between MRI disease activity scores of the sacroiliac joints (SIJs) and the spine in these patients was also assessed.

Methods: This was a cross-sectional study design in which adult patients who fulfilled the Assessment of SpondyloArthritis international Society classification criteria for aSpA and had active disease (Bath Ankylosing Spondylitis Disease Activity Index score ≥4, persistent spinal pain despite nonsteroidal anti-inflammatory drugs therapy >3 months) that required biologics therapy were included. The MRI disease activities were measured using the Spondyloarthritis Research Consortium of Canada (SPARCC) scores. Correlation between the SPARCC scores of the SIJs and the spine, and clinical DAI was calculated.

Results: Fifty-seven patients (47 men and 10 women; mean age 37 ± 12 years) completed the study. There was no statistically significant correlation between the SPARCC scores and clinical DAI. The SPARCC score of the SIJs showed a positive correlation with the SPARCC score of the spine (r = 0.34, p < 0.05). The thoracic discovertebral units (57%) were found to be more frequently associated with significant disease activity than the other levels of the spine.

Conclusion: MRI can detect active inflammation which may not be reflected by clinical DAI. MRI should be performed in patients with aSpA to provide a more comprehensive assessment and to better reflect disease activity and severity. MRI findings of more severe sacroiliitis should prompt the radiologist to look for involvement in the entire spine, particularly in the thoracic region.

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