Proportions of patients with single or combined lesions seen on MRI of the SIJ
| ASAS classification 2/3 readers | No SpA | Possible axSpA | Clinical arm only | MRI+mNY− | mNY+ |
|---|---|---|---|---|---|
| No. of patients | 72 | 89 | 53 | 51 | 22 |
| Single lesions | |||||
| Fatty lesions ≥1 | 10 | 11 | 14 | 18 | 11 |
| % | 13.8 | 12.4 | 26.4 | 35.3 | 50.0 |
| Fatty lesions ≥2 | 5 | 7 | 8 | 12 | 11 |
| % | 6.9 | 7.9 | 15.1 | 23.5 | 50.0 |
| Fatty lesions ≥3 | 2 | 3 | 8 | 8 | 10 |
| % | 2.8 | 3.4 | 15.1 | 15.7 | 45.5 |
| Erosions ≥1 | 15 | 29 | 21 | 40 | 17 |
| % | 20.8 | 32.6 | 39.6 | 78.4 | 77.3 |
| Erosions ≥2 | 6 | 15 | 8 | 32 | 15 |
| % | 8.3 | 16.9 | 15.1 | 62.7 | 68.2 |
| Erosions ≥3 | 3 | 6 | 7 | 24 | 14 |
| % | 4.2 | 6.7 | 13.2 | 47.1 | 63.6 |
| Sclerosis≥1 | 4 | 8 | 3 | 10 | 4 |
| % | 5.6 | 9.0 | 5.7 | 19.6 | 18.2 |
| Sclerosis ≥2 | 1 | 3 | 1 | 4 | 1 |
| % | 1.4 | 3.4 | 1.9 | 7.8 | 4.5 |
| Ankylosis ≥1 | 2 | 3 | 2 | 2 | 2 |
| % | 2.8 | 3.4 | 3.8 | 3.9 | 9.1 |
| Combination of lesions | |||||
| Fatty lesions and/or erosion ≥1 | 20 | 32 | 26 | 41 | 18 |
| % | 27.8 | 36.0 | 49.1 | 80.4 | 81.8 |
| Fatty lesions and/or erosion ≥2 | 11 | 17 | 14 | 32 | 17 |
| % | 15.3 | 19.1 | 26.4 | 62.7 | 77.3 |
| Fatty lesions and/or erosion ≥3 | 6 | 11 | 13 | 26 | 17 |
| % | 8.3 | 12.4 | 24.5 | 51.0 | 77.3 |
| Fatty lesions and/or erosion ≥4 | 4 | 10 | 7 | 22 | 14 |
| % | 5.6 | 11.2 | 13.2 | 43.1 | 63.6 |
| Fatty lesions and/or erosion ≥5 | 1 | 6 | 6 | 19 | 14 |
| % | 1.4 | 6.7 | 11.3 | 37.3 | 63.6 |
False positives ≤10% in italic; false positives ≤5% in italic and bold.
ASAS, Assessment of Spondyloarthritis international Society; axSpA, axial spondyloarthritis; mNY, modified New York criteria; SIJ, sacroiliac joint; SpA, spondyloarthritis.