Locations and descriptions of inflammatory changes
| Type of lesion | Description | Technical facts |
|---|---|---|
| Anterior/posterior spondylitis (figures 2 and 3) | ▶Typically located within bone marrow at one or more of the four corners of vertebral bodies | ▶T1w: usually low signal intensity ▶STIR: high signal intensity |
| ▶Often shaped triangular if located at a corner, but may also involve the whole vertebra (MIL*) | ||
| ▶(CIL*, RL†) | ||
| Spondylodiscitis (figure 4) | ▶Located within bone marrow at cortical plate adjacent to intervertebral disc | ▶T1w: usually low signal intensity |
| ▶Often hemispheric shape | ▶STIR: high signal intensity | |
| ▶Frequently at both sides of the intervertebral disc | ||
| ▶Usually confined to vertebral body and disc and does not spread to surrounding soft tissues | ||
| ▶(NIL*) | ||
| Arthritis of CV joints (figure 5) | ▶Any CV joint from T1 to T12 may be involved | ▶T1w: low signal intensity |
| ▶Associated with bone marrow oedema near CV joint, extending to pedicles, posterior aspect of vertebral bodies (lateral of spinal canal) and neighbouring rib | ▶STIR: high signal intensity ▶Only visualised on lateral slices (not showing spinal canal) | |
| ▶Additional axial and/or coronal slices may give additional information | ||
| ▶(Included in definition of LIL*) | ||
| ▶Note: Arthritis of costotransverse joints usually not detected on sagittal images | ||
| Arthritis of zygoapophyseal joints (facet joint arthritis) (FIL*/PIL*) (figure 6) | ▶Any facet joint from C2 to S1 may be involved | ▶T1w: low signal intensity |
| ▶Usually associated with bone marrow oedema within spinal pedicles (posterior of spinal canal) | ▶STIR: high signal intensity | |
| ▶Additional axial and/or coronal slices may be necessary | ▶Only visualised on lateral slices (not showing spinal canal) | |
| ▶Surrounding soft tissue oedema may occur | ||
| Enthesitis of spinal ligaments (figure 7) | ▶Direct evidence of inflammation can be frequently seen in the supraspinal ligament, interspinal ligaments and the ligamenta flava | ▶T1w: low signal intensity ▶ STIR: high signal intensity |
| ▶Inflammation of affected ligaments is usually associated with bone marrow oedema of adjacent bone (eg, spinous process) | ▶Note: T1w/Gd FS may give additional information to judge the extent of lesion | |
| ▶Signal changes of paraentheseal soft tissues (eg, musculature) may occur | ||
| ▶Included in the definition of PIL* |
↵* Abbreviations of the Canada–Denmark MRI in ankylosing spondylitis working group47 are given for reference.
↵† RL, Romanus lesion according to Bennett et al11 (see comment in the text). Each of the inflammatory lesions described must be visible in at least two or more consecutive sagittal slices.
CIL, corner inflammatory lesion; CV, costovertebral; LIL, lateral inflammatory lesion; MIL, massive inflammatory lesion; NIL, non-corner inflammatory lesion; PIL, posterior element inflammatory lesion; STIR, short τ inversion recovery; FIL, facet joint inflammatory lesion.