Session Type: Abstract Submissions (ACR)
Background/Purpose: The definition of a positive MRI as major criterion in the Assessment of SpondyloArthritis classification criteria for axial spondyloarthritis (SpA) is based on MRI of the sacroiliac joints (SIJ) alone. It is not known whether additional MRI of the spine may enhance diagnostic certainty over and above SIJ MRI alone. We aimed to assess the incremental diagnostic value of spinal MRI evaluated both separately from and combined with SIJ MRI in early SpA compared to SIJ MRI alone.
Methods: The study sample comprised 2 independent cohorts A/B of 130 consecutive patients with back pain ≤50 years newly referred to 2 university clinics, and 20 healthy controls (HC), in whom both SIJ and spinal MRI were available. Patients were classified according to clinical examination and pelvic radiography as having non-radiographic SpA (nr-axSpA; n=50), ankylosing spondylitis (AS; n=33), or mechanical back pain (MBP; n=47). SIJ and spinal MRI were assessed by 3 blinded readers according to standardized modules. Readers recorded presence/absence of SpA and their level of confidence in this conclusion by global evaluation of the MRI scans on a 0-10 scale (0 = definitely not SpA; 10 = definite SpA). SIJ alone and spinal MRI alone were read independently 6 months apart, with another interval of 1-3 months to the combined assessment of both SIJ and spinal MRI (combined read). We analysed differences between SIJ alone versus spinal MRI alone, and SIJ alone versus combined read of SIJ and spinal MRI. This was done descriptively by the number/percentage of subjects recorded concordantly by any 2 readers for each group and for the 2 cohorts.
Results: For cohorts A and B, respectively, and for assessment of SIJ and spinal scans independently there were 0% and 16.1% of nr-axSpA patients who showed spinal lesions in the absence of SIJ lesions, while 15.8% and 19.4% of nr-axSpA patients considered having a negative SIJ MRI showed a positive spinal MRI according to global assessment. Low confidence (5-7) in a diagnosis of SpA by global evaluation of SIJ MRI increased to high confidence (8-10) by global evaluation of spinal MRI in only 0% and 3.2% of nr-axSpA patients in the 2 cohorts. For cohorts A and B, 5.3% and 3.2% of nr-axSpA patients considered negative for SpA by SIJ MRI scan alone were re-classified as being positive for SpA by global evaluation of combined SIJ and spinal scans. 57.1% and 30.3% of the MBP patients (cohort A/B) showed lesions only on spinal MRI. Up to 15.0% and 18.2% of all controls were considered as having SpA by spinal MRI scan alone, based on spinal BME in 60.9% and on fat infiltration in 26.1% of these subjects.
Number (percentage) of subjects as recorded concordantly by any 2 readers for comparisons of SIJ alone versus spinal MRI alone, and SIJ alone versus combined SIJ and spinal MRI read
|Cohort||Cohort A (n=62)||Cohort B (n=88)|
|Number of subjects||19||9||14||20||31||24||33|
|Lesions SIJ-/Spine+||0 (0)||0 (0)||8 (57.1)||7 (35.0)||5 (16.1)||0 (0)||10 (30.3)|
|Global SIJ-/Spine+||3 (15.8)||0 (0)||1 (7.1)||3 (15.0)||6 (19.4)||0 (0)||6 (18.2)|
|Global SIJ-/Combination read+||1 (5.3)||0 (0)||0 (0)||0 (0)||1 (3.2)||0 (0)||0 (0)|
|Global Spine-/Combination read+||7 (36.8)||2 (22.2)||0 (0)||1 (5.0)||5 (16.1)||6 (25.0)||4 (12.1)|
Conclusion: Spinal MRI adds little incremental value compared to SIJ MRI alone in terms of lesion detection and classification of early SpA patients.
R. G. Lambert,
S. J. Pedersen,
W. P. Maksymowych,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/spinal-mri-has-little-incremental-diagnostic-value-compared-with-mri-of-the-sacroiliac-joints-alone-in-early-spondyloarthritis/