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 study1 suggests that a second MRI should be ordered for certain patients whose symptoms persist.
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.
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.
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.
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.
Patients whose second MRI is positive can receive an accurate diagnosis and receive appropriate treatment without delay.