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. 2021 Dec 28;74(2):243–250. doi: 10.1002/acr.24449

Figure 1.

Figure 1

Net progression from magnetic resonance imaging (MRI) of the sacroiliac (SI) joints (MRI‐SI joints) without structural lesions (MRI SIJ–) to MRI‐SI joints with structural lesions (MRI SIJ+) defined by ≥5 fatty lesions and/or erosions (A), ≥3 fatty lesions (B), and ≥3 erosions (C) according to baseline objective inflammatory markers (MRI‐SI joints inflammation and C‐reactive protein [CRP] level). MRI‐SIJ+ is defined as the presence of bone marrow edema on MRI‐SI joints according to the Assessment of SpondyloArthritis international Society definition. CRP+ is defined as a CRP level ≥6 mg/liter at baseline. Net progression from MRI SIJ– to MRI SIJ+ at year 5 is defined as the number of progressors minus the number of regressors divided by the total number of patients in each category (n = 144; MRI‐SI joints available both at baseline and year 5, and CRP level available at baseline).