PARIS, France—A group of French ankylosing spondylitis (AS) experts has developed a set of eight guidelines for deciding how to use imaging in the diagnosis and follow-up of AS in routine clinical practice. The panel, led by Stephan Pavy, MD, reports the evidence-based recommendations in Joint Bone Spine.1  The guidelines project was funded by Abbott France.

"No specific laboratory markers for AS have been identified to date, and imaging is therefore crucial for the diagnosis...These recommendations...underline the usefulness of MRI of the sacroiliac joints and spine for diagnosing AS at an early stage, before radiographic changes develop. For routine follow-up and evaluation of treatment responses, the experts established that no imaging is needed, since radiographs show limited sensitivity to change and no conclusive data are available regarding other imaging methods," writes Dr. Pavy, who is at Pitié-Salpêtrière Hospital, in Paris, France.

First of three sets of recommendations

The imaging guidelines are the first of three types of recommendations being developed for axial forms of AS. Future recommendations will cover clinical and laboratory tests for follow-up and the role for medications other than biotherapies, Dr. Pavy said. The grading of each recommendation was based on the level of evidence. None of the recommendations are Grade A  due to "the absence of conclusive data from high-quality studies."

The guidelines are based primarily on 73 published articles; expert opinion was used to fill in gaps in the evidence. The final recommendations were reviewed and voted on by an expert panel of 94 rheumatologists.

Eight basic imaging guidelines adopted

The review panel concluded that:

  • AS diagnosis requires standard radiographs of the pelvis and lumbar spine
  • Further imaging is unnecessary if standard radiographs conclusively show bilateral sacroiliitis
  • Magnetic resonance imaging (MRI) of the sacroiliac joints should be performed if radiographs are normal or doubtful in a patient with a clinical suspicion of AS
  • MRI of the spine should be performed for AS diagnosis in patients with inflammatory back pain and "nonsuggestive radiographs" of pelvis and spine
  • Radiographs, Doppler ultrasound, MRI, or radionuclide scanning should be used for evaluating entheseal involvement for patients with suspected AS
  • Imaging other than standard radiography is not useful for predicting the functional or structural outcome of AS
  • Imaging is not appropriate for routine follow-up in AS but "should be performed as dictated by the clinical course"
  • Imaging is not recommended for evaluating response to AS treatment

The panel noted that attempts to identify factors that predicted the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) in a cohort of 137 patients followed for 4 years found that only baseline mSASSS, hip involvement, and male gender made statistically significant contributions to the radiographic score. "The literature review found no data on the use of other imaging methods for predicting AS outcomes," it concluded.

The panel also notes that routine follow-up radiographs "rarely show significant progression of structural damage due to AS" and that imaging "either shows limited sensitivity to change or fails to correlate closely with clinical responses."

Figure. Guidelines for imaging in AS

  1. The diagnosis of ankylosing spondylitis requires standard radiographs of the pelvis (anteroposterior view) and lumbar spine (anteroposterior and lateral views including the thoracolumbar junction).
  1. When standard radiographs conclusively demonstrate bilateral sacroiliitis, further imaging studies are not necessary for establishing the diagnosis of ankylosing spondylitis.
  1. When radiographs are normal or doubtful in a patient with a clinical suspicion of ankylosing spondylitis, diagnostic MRI of the sacroiliac joints is recommended.
  1. MRI of the spine can contribute to the diagnosis of ankylosing spondylitis in patients who have inflammatory back pain with nonsuggestive radiographs of the pelvis and spine.
  1.  To evaluate entheseal involvement in patients with a clinical suspicion of ankylosing spondylitis, radiographs may be useful and, if needed, Doppler chronography or MRI may deserve to be performed, or radionuclide scanning when multiple entheses are involved.
  1. Given the current state of knowledge, imaging methods other than standard radiography are not useful to predict the functional or structural outcome of ankylosing spondylitis.
  1. Given the current state of knowledge, imaging is not appropriate for the routine follow-up of patients with ankylosing spondylitis. Instead, additional imaging should be performed as dictated by the clinical course.
  1. Given the current state of knowledge, imaging is not recommended for evaluating treatment responses in patients with ankylosing spondylitis.

Source: Pavy S, et al.1

 

Reference

1. Pavy S, Dernis E, Lavie F, et al. Imaging for the diagnosis and follow-up of ankylosing spondylitis: development of recommendations for clinical practice based on published evidence and expert opinion. Joint Bone Spine. 2007;74:338-345.