By Bill Schu
A study in PLOS One found evidence that fat metaplasia in sacroiliac joints (SIJ) is significantly associated with spinal progression for axial spondyloarthritis (axSpA).
AxSpA falls into two categories: non-radiographic axSpA, in which there is no evidence of sacroiliitis on conventional radiographs, and ankylosing spondylitis (AS), in which there is definitive evidence of sacroiliitis. Radiographic progression in the spine is strongly associated with spinal mobility and functional status, and therefore represents a clinically important outcome and treatment target in those with axSpA.
Because spinal progression varies widely among patients with axSpA, it is clinically important to be able to predict radiographic spinal progression. Magnetic resonance imaging (MRI) can detect active inflammatory lesions in the SIJs, particularly on fat-suppressed (FS) images and can also detect both post-inflammatory changes including MRI-specific fatty lesions (fat metaplasia) and chronic changes (sclerosis, erosion, and ankyloses).