Sacroiliac Joint MRI for Diagnosis of Nonradiographic Axial Spondyloarthritis, Other Conditions

Through magnetic resonance imaging (MRI) of the sacroiliac joints, researchers detected inflammatory and structural lesions in all segments of the joint among patients with spondyloarthritis (SpA), according to findings published in Therapeutic Advances in Musculoskeletal Disease.

Utilizing the definitions established by the Assessment of SpondyloArthritis international Society (ASAS) MRI working group, 2 experienced readers assessed the MRI images to detect bone marrow edema (BME), subchondral sclerosis, fatty lesions, erosions, and ankylosis. Sacroiliac joints were divided into 5 segments: upper, antero-middle, intermediate-middle, postero-middle, and lower, noted study authors.

“The clear presence of BME on two consecutive slices of an MRI of the SI joint or multiple BME lesions on a single slice, highly suggestive of SpA, defines sacroiliitis, according to the ASAS,” explained researchers.” “Sacroiliitis patients are further classified as nonradiographic axial spondyloarthritis (nraxSpA) in the absence of radiographic sacroiliitis and as radiographic (r)-axSpA in presence of radiographic sacroiliitis, according to the imaging arm of the ASAS classification criteria.”

Of 200 patients included in the study, 96 had SpA (mean age 37.4 ± 11.8 years) and 104 did not (mean age 39.9 ± 11.6 years). When compared 65% of SpA patients had inflammatory buttock pain vs 25% of non-SpA patients.

Researchers observed BME in 65% of SpA patients, mainly in the intermediate-middle segment and in 20% of non-SpA patients predominantly in the antero-middle segment. In 44% of non-SpA patients, subchondral sclerosis occurred, mostly in the antero-middle segment compared to 36% in SpA patients.

Furthermore, fatty lesions were detected in 34% of SpA patients vs 21% of non-SpA patients, while erosions were observed in 60% of SpA patients and 25% of non-SpA patients. According to researchers, in the postero-middle segment in non-SpA patients, BME and structural lesions were minimally observed.

“Thus, precise analysis of the distribution of all lesions, both inflammatory and structural, and the integration of the clinical context are necessary to determine the origin of the abnormalities visualized on MRI of the SI joints,” concluded study authors.

Reference:
Hecquet S, Lustig JP, Prati C, et al. Frequency and anatomic distribution of magnetic resonance imaging lesions in the sacroiliac joints of spondyloarthritis and non-spondyloarthritis patients. Ther Adv Musculoskelet Dis. Published online September 5, 2022. doi:10.1177/1759720X221119245