Scores for chronic inflammatory changes on MRI
| Finding on MRI | Spine score per VU | SI joint score per quadrant/joint |
|---|---|---|
| Fatty lesion | 0: normal bone marrow | 0: fatty lesions absent |
| 1: fatty lesions of <25% of VU area | 1: fatty lesions present | |
| 2: fatty lesions of ≥25% and <50% of VU area | NA | |
| 3: fatty lesions of ≥50% of VU area | NA | |
| Erosions* | 0: no erosion | 0: normal joint margin |
| 1: erosion <25% of vertebral end plate | 1: 1–2 erosions | |
| 2: erosion ≥25% of vertebral end plate | 2: 3–5 erosions | |
| NA | 3: >5 erosions | |
| Ankylosis* | 0: no ankylosis | 0: ankylosis absent |
| 1: syndesmophyte growth, not bridging | 1: ankylosis present | |
| 2: syndesmophyte growth, bridging (anterior/posterior) | NA | |
| 3: transdiscal ankylosis | NA |
Maximum fatty lesion score per patient: 69 for spine and 8 for SI joints; maximum erosion score per patient: 46 for spine and 6 for SI joints; maximum ankylosis score per patient 69 for spine and 2 for SI joints.
↵* Erosions and ankylosis in the spine were scored on the VU level; in the SI joints erosions and ankylosis were scored for left and right SI joint (not per quadrant).
NA, not applicable; SI joint, sacroiliac joint; VU, vertebral unit.