Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose: The ASAS definition of a positive MRI of the sacroiliac joints (MRI-SI+) for the classification of axial spondyloarthritis (axSpA) patients includes inflammatory lesions only1,2. The role of structural lesions on MRI-SI in classifying patients is unclear1. We explored the potential role of structural lesions on MRI-SI in classifying axSpA patients.
Methods: Patients with back pain (≥3 months, ≤2 years, onset <45 years) from the 5 centers in the SPondyloArthritis Caught Early (SPACE)-cohort were included. Patients underwent MRI-SI. MRI were scored by 3 well-calibrated readers independently for ankylosis, sclerosis, erosions, and fatty lesions (FL) (T1-weighted images; STIR viewed simultaneously). Erosions, sclerosis and FL were defined according to the MORPHO definition3 (≥1 lesion on ≥2 consecutive slices or ≥2 lesion on 1 slice). Ankylosis was defined as ≥1 lesion on ≥1 slice. Lesions were considered present if 2/3 readers agreed. MRI was considered positive for several (combinations of) structural lesions (MRI-SI-s+) using cut-offs based on the acceptance of ≤5% false-positives in patients without SpA. Patients are considered as possible axSpA if not fulfilling the ASAS axSpA criteria3, but if ≥1 specific SpA-feature (LR+ >6) or ≥2 less specific SpA-features (LR+ <6) are present4. We classified possible axSpA patients using MRI-SI-s+ instead of MRI-SI+ and calculated the LR product with LR+ 9.0 for MRI-SI-s+ as if MRI-SI+4. Based on the LR product the probability of having axSpA was calculated4.
Results: Only possible axSpA patients with MRI-SI data were included (n=116). Depending on the used MRI-SI-s+ definition, 1% (ankylosis ≥1) to 6% (erosions ≥2 or FL ≥2) of the possible axSpA patients could be classified as axSpA (table). Combining the various definitions of MRI-SI-s+ results in 14 additional patients (12.1%) classified as axSpA (5 patients with probability ≥80%); 5 patients fulfilled 4 of the proposed MRI-SI-s+ definitions. In patients with a high number of SpA-features, using MRI-SI-s+ to calculate the LR product results in a probability ≥80%, making an axSpA diagnosis very likely. However, in patients with only 1 or a few SpA-features, the probability remains <80%.
Conclusion: These explorative data point out that structural lesions on MRI of the SI joints might play a role in classifying possible axSpA patients. However, only few additional patients are classified as axSpA with a high probability while the same number of patients with a low probability would (falsely) be classified if structural lesions would be added to the definition of a positive MRI. Further studies are needed to define the best type/combination and cut-off of structural lesions.
References: 1Rudwaleit ARD 2009;68:1520-7 2Rudwaleit ARD 2009;68:777-83 3Weber A&R 2010;62:3048-58 4Rudwaleit ARD 2004;63:535-43
|
ASAS axSpA+ in possible axSpA patients if structural lesions are added |
Possible axSpA n=116 |
Mean (range) no. SpA-features |
Probability ≥80% |
Probability 50-79% |
Probability 20-49% |
Probability <20% |
|
Ankylosis ≥1 |
1 (0.9%) |
1 (1) |
– |
– |
– |
1 |
|
Fatty lesions ≥2 |
7 (6.0%) |
2.3 (1-4) |
3 |
1 |
1 |
2 |
|
Erosion ≥2 |
7 (6.0%) |
2.1 (2-3) |
3 |
1 |
2 |
1 |
|
Sclerosis ≥1 |
1 (0.9%) |
1 (1) |
– |
– |
– |
1 |
|
Any structural lesions ≥5 |
5 (4.3%) |
2.4 (1-3) |
2 |
2 |
– |
1 |
|
Any structural lesions (except ankylosis) ≥5 |
4 (3.4%) |
2.8 (2-3) |
2 |
2 |
– |
– |
|
Fatty lesions and/or erosions ≥5 |
4 (3.4%) |
2.8 (2-3) |
2 |
2 |
– |
– |
Disclosure:
R. van den Berg,
None;
M. de Hooge,
None;
F. van Gaalen,
None;
V. Navarro-Compán,
None;
M. Reijnierse,
None;
K. Fagerli,
None;
R. Landewé,
None;
M. van Oosterhout,
None;
R. Ramonda,
None;
T. Huizinga,
None;
D. van der Heijde,
None.
« Back to 2013 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/influence-of-taking-structural-lesions-into-account-in-addition-to-inflammatory-lesions-on-mri-of-the-sacroiliac-joints-on-the-classification-of-patients-with-possible-axial-spondyloarthritis/