Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose:
MRI of the sacroiliac joint (SIJ) is included in the ASAS classification criteria for axial spondyloarthritis (axSpA) to identify patients at an earlier stage of the disease. However, the diagnostic utility is discussed since there are only few MRI data of patients with chronic low back pain and healthy populations. Therefore, we investigated the frequencies of bone marrow edema (BME) and structural lesions (SL) in a large cohort of axSpA patients, chronic low back pain (CLBP) patients and healthy controls (HC). Furthermore, to assess the added value of structural lesions for the sensitivity of a MRI of the SIJ (MRI-SIJ).
Methods:
A cross-sectional study (CaFaSpA 2) was set up among primary care patients with CLBP aged 18-45 years (n=579) and healthy controls (n=79). The healthy controls were oversampled towards physical active controls and therefore included 25 runners. Also 4 women with pregnancy related pelvic pain were included. In all participants a MRI-SIJ was obtained. MRIs-SIJ were scored by one out of two experienced radiologist, blinded for clinical status. MRI evaluation followed ASAS recommendations for BME and SL, (ankylosis, sclerosis, erosions and fatty lesions).1 The outcome was reported by descriptive statistics. To analyze the added value of SL as a MRI positive feature we tested the sensitivity and specificity.
Results:
95 out of 579 CLBP patients fulfilled the ASAS classification criteria for axSpA.2 BME was observed in 71% of the axSpA patients, in 5% of the CLBP patients and in 14% of the HC. This resulted in a sensitivity of 71% and a specificity of 95%. No relationship between physical activity or pregnancy related back pain and BME frequency was observed.
The frequencies of structural lesions were 25%, 7%, and 8% for respectively, axSpA patients, CLBP patients and HCs. The sensitivity of the MRI, based only on the presence of BME, is 71%, with a 95% specificity. Adding the structural lesions as an MRI positive feature would increase the sensitivity to 84%, with a slight decrease in specificity, 88%.
Table 1. Patients characteristics and frequencies of BME and structural lesions (SL) on MRI-SIJ
|
|
ASAS aSpA patients (n=95) |
CLBP patients (n=484) |
Healthy controls (n=79) |
||
|
|
Radiographic SpA (n=24) |
Nonradiographic SpA (n=71) |
Total(n=95) |
|
|
|
Male n (%) |
6 (25) |
36 (42) |
36 (38) |
202 (42) |
33 (42) |
|
Age yrs (sd) |
38.6 (5.8) |
36.8 (6.6) |
37.3 (6.5) |
35.8 (7.1) |
36.9 (7.4) |
|
CLBP duration yrs (sd) |
9.3 (9.9) |
9.6 (7.4) |
9.5 (8.1) |
9.2 (7.7) |
NA |
|
BME n (%) * |
8 (33) |
59 (83) |
67 (71) |
24 (5) |
11 (14) |
|
SL n (%) ° |
16 (67) |
8 (11) |
24 (25) |
36 (7) |
6 (8) |
|
BME or SL n (%) |
19 (79) |
61 (86) |
80 (84) |
57 (12) |
15 (19) |
*BME lesion present on at least two consecutive slices or more than one signal on a single slice.
° Fat depositions, sclerosis, erosions or ankylosis.
Conclusion:
Bone marrow edema on MRI will be seen in 5% to 14% of the chronic low back pain patients and healthy controls. Structural lesions will be seen in 7% to 8% of these populations. The added value of structural lesions in diagnosing axSpA is promising, since it increases the sensitivity and therefore facilitates the diagnostic utility of MRI-SIJ.
1. Sieper J ARD 2009;68 Suppl 2:ii1-44.
2. Rudwaleit M ARD;2009;68:777-83.
Disclosure:
L. van Hoeven,
None;
J. J. Luime,
None;
P. D. M. de Buck,
None;
J. M. W. Hazes,
None;
A. E. A. M. Weel,
Abbott Immunology Pharmaceuticals,
2.
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