Utility of selected sequence MRI imaging of the axial skeleton in the diagnosis of axial spondyloarthritis.

Background: Whole body MRI has been used to evaluate inflammatory lesions associated with axial spondyloarthritis (SpA). These sequences are extensive, time consuming and add to the cost of the investigation. We aimed to determine the utility of selected sequence MRI imaging of the axial skeleton including spine, pelvis and sacroiliac (SI) joints to identify features of (SpA).

Methods: A retrospective study was conducted on 76 patients diagnosed with SpA that underwent a selective sequence MRI imaging of the axial skeleton. The MRI were reported by two musculoskeletal trained radiologists were reviewed. The MRI sequences included whole spine sequences of sagittal STIR (short tau inversion recovery), T1 weighted and T2 weighted sequences. Coronal STIR and T1 weighted images were studied for SI joints and pelvis. The MRI were assessed based on the guidelines outlined by the Assessment of SpondyloArthritis International Society (ASAS) for features of spondylitis, spondylodiscitis, enthesitis, synovitis, capsulitis, bone marrow edema, fatty marrow replacement, erosions and bony ankylosis. Inflammatory lesions were documented in the spine, sacroiliac, facet, hip and costovertebral joints.

Results: The mean scan duration was 28 min. SI joint involvement was noted in 74 (97.3%) of patients. The other most prevalent findings were spondylitis in 44 (57.8%) patients, costovertebral joint involvement in 31 (40.7%), facet joint lesions in 32 (42.1%), spondylodiscitis in 21 (27.6%), enthesitis in 13 (17.1%), hip lesions in 16 (21%) and ankylosis in 10 (13.1%).

Conclusions: This selective sequence imaging of the pelvis and spine was able to identify typical lesions of SpA in a shorter time period. Fifty-five percent patients had lesions in the posterior elements including facet joints and costovertbral joints that would be missed on traditional SI joint imaging.