When a doctor suspects a patient has axial spondyloarthritis, such as ankylosing spondylitis, he or she typically orders an MRI to see if the sacroiliac joint in the low back is inflamed. This inflammation, called sacroiliitis, is a hallmark of spondyloarthritis. But what if the MRI comes back normal? A recent study 1 Sengupta R, Marzo-ortega H, Mcgonagle D, Wadeley A, Bennett AN. Short-term Repeat Magnetic Resonance Imaging Scans in Suspected Early Axial Spondyloarthritis Are Clinically Relevant Only in HLA-B27-positive Male Subjects. J Rheumatol. 201 suggests that a second MRI should be ordered for certain patients whose symptoms persist.

See Ankylosing Spondylitis Symptoms

Axial spondyloarthritis causes painful inflammation in the spine and/or the sacroiliac joints. Read Understanding the Different Names and Classifications for Spondyloarthritis (SpA)

MRIs may show inflammation developing over time

The study, published in the Journal of Rheumatology, followed 29 patients with suspected axial spondyloarthritis. Patients were asked to have MRIs at the beginning of the study and then again at 4, 8 and 12 weeks. For 4 patients, the initial MRIs were negative, meaning they did not show evidence of sacroiliitis or other spinal inflammation, but the 12-week MRIs were positive. Other patients’ MRIs remained positive or negative throughout the study.

All 4 patients whose MRIs showed changes carried the gene HLA-B27, which predisposes people to spondyloarthritis. Based on the findings, the researchers suggest that patients undergo a second MRI if they:

  • Have suspected spondyloarthritis,
  • Carry the HLA-B27 gene, and
  • Had a previously negative MRI.

See Ankylosing Spondylitis Causes and Risk Factors

Of the 4 patients, 3 were male and 1 was female. Based on that evidence, researchers particularly encouraged a second MRI for male patients.


Other joints of the spine may be inflamed
It is not necessary to have sacroiliitis to receive a diagnosis of axial spondyloarthritis. Other joints of the spine, such as joints in the neck’s cervical spine, may be inflamed instead. Like sacroiliitis, this inflammation may also develop gradually and be seen on an MRI.

See Progression of Ankylosing Spondylitis in the Spine

Why do these study results matter?

Many cases of axial spondyloarthritis develop gradually—an occasional low backache may slowly turn into a chronic backache with fatigue, or a stiff and swollen neck may persist and be followed by other painfully swollen joints.

See Development and Progression of Ankylosing Spondylitis

This gradual onset can make axial spondyloarthritis difficult to diagnose. If a patient’s spinal inflammation doesn’t show up on an initial MRI a doctor may rule out spondyloarthritis, potentially delaying an accurate diagnosis for months or even years.

See Ankylosing Spondylitis Diagnosis

Patients whose second MRI is positive can receive an accurate diagnosis and receive appropriate treatment without delay.

Learn more:

Ankylosing Spondylitis Treatment

Ankylosing Spondylitis Medications