Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose: Little is known about the prevalence of structural lesions on MRI in the SI joints (MRI-SI) in recent onset axial spondyloarthritis (axSpA) patients and patients with back pain of other origin. Therefore, we investigated the prevalence of structural lesions on MRI-SI in these patients.
Methods: Patients with back pain (≥3 months, ≤2 years, onset <45 years) from the 5 centers the SPondyloArthritis Caught Early (SPACE)-cohort were included. Patients underwent MRI-SI. Available MRIs-SI were scored by 3 well-calibrated readers independently for ankylosis, sclerosis, erosions, and fatty lesions (MRI T1-weighted images; STIR images viewed simultaneously). Erosions, sclerosis and fatty lesions were defined according to the MORPHO definition1 (≥1 lesion on ≥2 consecutive slices or ≥2 lesion on 1 slice); ankylosis as 1 lesion on ≥1 slice. Lesions were considered present if 2/3 readers agreed. Prevalence based on several cut-offs of structural lesions was calculated. Patients were grouped according to the ASAS axSpA criteria2[imaging-arm (mNY+, mNY-), clinical arm], no-SpA and possible SpA.
Results: Patients with MRI-SI data were included (n=299). If defined as ≥1, all structural lesions except ankylosis were frequent in all groups; in decreasing frequency in mNY+, MRI+mNY-, clinical arm, possible SpA and no-SpA (table). The higher the cut-offs, the better discrimination between the imaging-arm and no/possible SpA, with the clinical arm close to no/possible SpA. To define a proper cut-off for the presence of structural lesions in axSpA, the false-positive percentage in no-SpA patients should be low. We defined possible cut-offs based on the acceptance of ≤10% (italics) and ≤5% (bold) false-positives (table). E.g. if ≥4 structural lesions are present, false-positives are 6.0% and 5.2% respectively, with a frequency of 61.5% and 43.5% in the mNY+ and MRI+mNY- subgroups.
Conclusion: Prevalence of erosions, sclerosis and fatty lesions on MRI-SI is high in axSpA patients but also in no-SpA patients. Higher cut-offs than ≥1 lesion are needed to reduce false-positives; also with higher cut-offs structural lesions are frequent in early axSpA patients. These data suggest that with appropriate cut-offs, structural lesions might be helpful in defining sacroiliitis on MRI.
References: 1Weber A&R 2010;62:3048-58 2Rudwaleit ARD 2009;68:777-83
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AxSpA (ASAS), n=123 |
Possible SpA n=116 |
No SpA n=60 |
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mNY+ (n=26) |
mNY- (n=46) |
Clinical arm (n=51) |
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Fatty lesion ≥1, n (%) |
11 (42.3) |
12 (26.1) |
7 (13.7) |
8 (6.9) |
6 (10.0) |
|
Fatty lesion ≥2, n (%) |
11 (42.3) |
10 (21.7) |
6 (11.8) |
7 (6.0) |
2 (3.3) |
|
Erosion ≥1, n (%) |
18 (69.2) |
30 (65.2) |
11 (21.6) |
22 (19.0) |
5 (8.3) |
|
Erosion ≥2, n (%) |
13 (50.0) |
24 (52.2) |
3 (5.9) |
8 (6.9) |
3 (5.0) |
|
Sclerosis ≥1, n (%) |
1 (3.8) |
3 (6.5) |
1 (2.0) |
2 (1.7) |
2 (3.3) |
|
Ankylosis ≥1, n (%) |
2 (7.7) |
1 (2.2) |
0 (0.0) |
1 (0.9) |
1 (1.7) |
|
Fatty lesion and/or erosion ≥1, n (%) |
19 (73.1) |
32 (69.9) |
14 (27.5) |
28 (24.1) |
11 (18.3) |
|
Fatty lesion and/or erosion ≥3, n (%) |
16 (61.5) |
20 (43.5) |
6 (11.8) |
9 (7.8) |
6 (10.0) |
|
Fatty lesion and/or erosion ≥4, n (%) |
16 (61.5) |
18 (39.1) |
5 (9.8) |
4 (3.4) |
4 (6.7) |
|
Fatty lesion and/or erosion ≥5, n (%) |
16 (61.5) |
18 (39.1) |
3 (5.9) |
4 (3.4) |
0 (0.0) |
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Any structural lesion ≥1, n (%) |
20 (76.9) |
36 (78.3) |
16 (31.4) |
34 (29.3) |
14 (23.3) |
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Any structural lesion ≥4, n (%) |
16 (61.5) |
20 (43.5) |
7 (13.7) |
7 (6.0) |
5 (8.3) |
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Any structural lesion ≥5, n (%) |
16 (61.5) |
20 (43.5) |
5 (9.8) |
6 (5.2) |
2 (3.3) |
|
Any structural lesion, no ankylosis ≥1, n (%) |
19 (73.1) |
35 (76.1) |
15 (29.4) |
29 (25.0) |
13 (21.7) |
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Any structural lesion, no ankylosis ≥4, n (%) |
16 (61.5) |
19 (41.3) |
6 (11.8) |
6 (5.2) |
5 (8.3) |
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Any structural lesion, no ankylosis ≥5, n (%) |
16 (61.5) |
19 (41.3) |
4 (7.8) |
5 (4.3) |
1 (1.7) |
|
Any structural lesion, no sclerosis ≥1, n (%) |
20 (76.9) |
32 (69.6) |
16 (31.4) |
32 (27.6) |
12 (20.0) |
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Any structural lesion, no sclerosis ≥3, n (%) |
17 (65.4) |
21 (45.7) |
7 (13.7) |
11 (9.5) |
6 (10.0) |
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Any structural lesion, no sclerosis ≥5, n (%) |
16 (61.5) |
19 (41.3) |
4 (7.8) |
4 (3.4) |
1 (1.7) |
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Italics represents ≤10% false-positives in the group of no SpA patients. Bold represents ≤5% false-positives in the group of no SpA patients |
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Disclosure:
R. van den Berg,
None;
M. de Hooge,
None;
V. Navarro-Compán,
None;
M. Reijnierse,
None;
F. van Gaalen,
None;
K. Fagerli,
None;
M. Turina,
None;
M. van Oosterhout,
None;
R. Ramonda,
None;
T. Huizinga,
None;
D. van der Heijde,
None.
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