MRI and x-ray findings on spine and sacroiliac joints (apart from those included in the ASAS criteria) in patients with early axial spondyloarthritis
| ASAS criteria | |||||
|---|---|---|---|---|---|
| Imaging* | Clinical† | ||||
| X-ray+/MRI+‡ | X-ray+/MRI−§ | X-ray−/MRI+¶ | X-ray−/MRI−/abnormal CRP** | X-ray−/MRI−/normal CRP | |
| Number | 126 | 47 | 89 | 32 | 138 |
| MRI: SIJ structural damage†† | 92 (73.0) | 21 (50.0) | 31 (34.8) | 3 (9.4) | 3 (2.2) |
| MRI: spine inflammatory lesions‡‡ | 53 (42.7) | 9 (21.4) | 30 (34.1) | 7 (21.9) | 15 (10.9) |
| MRI: spine structural damage§§ | 18 (14.5) | 3 (7.1) | 6 (6.9) | 2 (6.3) | 7 (5.1) |
| X-ray: spine¶¶ | 14 (11.1) | 11 (23.4) | 6 (6.7) | 3 (9.4) | 6 (4.4) |
Values are number (%).
*Either definite damage of SIJs on pelvic x-ray analysis according to the modified New York criteria8 or inflammatory lesion of SIJs at MRI as defined in the Methods section.
†Presence of HLA-B27 plus two clinical features of SpA.
‡Presence of both structural damage on pelvic x-ray analysis and MRI-determined inflammatory changes in SIJs.
§Presence of structural damage of SIJs on pelvic x-ray analysis without MRI-determined inflammatory changes.
¶Presence of MRI-determined inflammatory changes in SIJs without structural damage on pelvic x-ray analysis.
**Abnormal CRP defined as >6 mg/L.
††Structural damage of SIJs on MRI defined as clear characteristic lesions such as sclerosis, erosions, bone bridges or ankylosis.
‡‡Inflammatory changes in the spine defined as bone oedema in or adjacent to the entheses at the margin of the vertebrae or whole vertebrae (with or without disc involvement), compatible with lesions observed in cases of ankylosing spondylitis.
§§Structural damage of the spine defined as clear characteristic lesions such as sclerosis, erosions or syndesmophytes on the vertebrae.
¶¶X-ray-revealed spine abnormalities defined as an mSASSS of 2 with at least one syndesmophyte at at least one vertebral edge.25
ASAS, Assessment of Spondyloarthritis International Society; CRP, C-reactive protein; mSASSS, modified Stoke Ankylosing Spondylitis Spine Score; SIJ, sacroiliac joint.