Magnetic resonance imaging (MRI) scans of the sacroiliac joints should not be used as the sole means of diagnosing axial spondyloarthropathy (axSpA), according to a study presented at the recent ACR/ARHP Annual Meeting in San Diego.
AxSpA is an inflammatory disease with low back pain as its main symptom. Spondyloarthritis (SpA) can also affect the arm and leg joints, and organs such as the skin, eyes or intestines. Inflammation often affects the sites where ligaments and tendons attach to bones.
The condition most commonly occurs in people in their teens and 20s, especially young men, according to the American College of Rheumatology.
Researchers in the Netherlands and France analysed radiographs and MRI scans of the sacroiliac joints and spine of 47 healthy individuals and compared them against those for 47 people with axSpA and 47 with chronic back pain, as well as seven women with postpartum back pain lasting several months, and 24 frequent runners.
The findings showed that a substantial number of healthy people have positive sacroiliac MRI results.
Among the healthy individuals, 11 out of 47 had a positive MRI, compared to 43 of the 47 axSpA patients and three of the 47 back pain patients. The results also showed that three of the 24 frequent runners and four of the seven women with postpartum back pain had positive sacroiliac MRI results.
Deep bone marrow edema lesions were not found in the healthy individuals, chronic back pain patients or frequent runners, but were found in 38 of the 47 axSpA patients and one of the seven women with post-partum back pain, suggesting that these lesions are exclusive of sacroiliitis in axSpA patients.
“Sacroiliac MRI has become an important aid in diagnosing SpA, since sacroiliac joint inflammation and damage are hallmarks of this disease,” said lead author Dr Robert Landewé, Professor of Rheumatology at the University of Amsterdam in the Netherlands. “Unfortunately, physicians all too often pay too much attention to a positive MRI, and consider it a decisive feature in the diagnosis. We have learned that sacroiliac MRI can also be positive in unaffected, or healthy, individuals.”
Dr Landewé concluded: “This study provides an estimate of how frequently positive sacroiliac MRIs can be found in individuals without SpA, or specificity. Rheumatologists now better realise that they cannot make a diagnosis of SpA solely based on a positive MRI.”