Replacing Radiographic Sacroiliitis By Structural Lesions on MRI of the Sacroiliac Joints in Two Early Axial Spa Cohorts: What Is the Impact on the Classification of Patients According to the ASAS Axial Spa Criteria?

Pauline Bakker¹, Rosaline van den Berg², Manouk de Hooge³, Zineb Ez-Zaitouni⁴, Miranda van Lunteren⁴, Karen M. Fagerli⁵, Roberta Ramonda⁶, Robert B. M. Landewé⁷, Maikel van Oosterhout⁸, Monique Reijnierse⁹, Floris van Gaalen¹, Pascal Claudepierre¹⁰, Daniel Wendling¹¹, Maxime Dougados¹² and Désirée van der Heijde¹³, ¹Rheumatology, Leiden University Medical Center, Leiden, Netherlands, ²Leiden University Medical Center, Leiden, Netherlands, ³Department of Rheumatology, Leiden University Medical Centre, Leiden, Netherlands, ⁴Leiden University Medical Centre, Leiden, Netherlands, ⁵Rheumatology, Diakonhjemmet Hospital, Oslo, Norway, ⁶Cattedra, Voc Rheumatology, University of Padua, Padova, Italy, ⁷Rheumatology, University Hospital Maastricht, Maastricht, Netherlands, ⁸Rheumatology, GHZ Hospital, Gouda, Netherlands, ⁹Radiology, Leiden University Medical Center, Leiden, Netherlands, ¹⁰Hôpital Henri Mondor, Créteil, France, ¹¹Université de Franche-Comté, Besançon, France, ¹²Paris-Descartes University, Paris, France, ¹³Department of Rheumatology, Leiden University Medical Center, Leiden, the Netherlands, Leiden, Netherlands

Meeting: 2015 ACR/ARHP Annual Meeting

Date of first publication: September 29, 2015

Keywords: MRI, radiography and spondylarthritis

Session Information

Date: Monday, November 9, 2015

Title: Imaging of Rheumatic Diseases II: MRI, PET and CT

Session Type: ACR Concurrent Abstract Session

Session Time: 2:30PM-4:00PM

Background/Purpose: Conventional radiography of the sacroiliac joints (X-SI) is the most commonly used imaging technique to detect structural lesions in axial SpondyloArthritis (axSpA). However, a reliable detection of radiographic sacroiliitis is challenging and might result in misclassification. Next to inflammatory lesions, structural lesions are visible on MRI. We aim to investigate the impact of replacement of X-SI by structural lesions on MRI on the ASAS axSpA classification of patients.

Methods: Patients in the SPondyloArthritis Caught Early (SPACE) cohort (chronic back pain: ≥3 mths, ≤2 yrs, onset <45 yrs) and DEvenir des Spondylarthropathies Indifférenciées Récentes (DESIR) cohort (aged 18-50 with inflammatory back pain (IBP): ≥3 mths, <3 yrs) with (suspicion of) axSpA underwent baseline MRI-SI and X-SI. Three well-calibrated readers, blinded for patient characteristics, read the images. MRI-SI (inflammatory lesions according to ASAS definition) and X-SI (modified New York criteria (mNY)) were considered positive if 2/3 readers agreed. MRI T1-w images were assessed on the presence of structural lesions. Mean scores of 2/3 agreeing readers (ASAS definition) were used in SPACE; in DESIR there were only 2 readers for MRI-SI-s and results were analysed for each reader separately. Previously, we proposed cut-offs to define a positive MRI-SI based on structural lesions (MRI-SI-s) based on <5% presence among no-SpA patients in the SPACE cohort: ≥3 erosions, ≥3 fatty lesions, ≥5 fat lesions and/or erosions. In this analysis, patients were classified according to the ASAS axSpA criteria using MRI-SI-s instead of X-SI and changes were visualized.

Results: In total, 294 (SPACE) and 582 (DESIR) patients were included of which 103 (35.0%) and 418 (71.8%) patients were classified as having ASAS axSpA, respectively. Using the ≥5 fatty lesions and/or erosions cut-off, classification did not change in 275+3+8 (286) patients (97.3%) in SPACE, not in 478+66+23 (567) patients (97.4%) by reader 1 in DESIR and not in 469+43+54 (566) (97.3%) patients by reader 2 in DESIR (table). In SPACE, 5 patients (1.7%) would not be classified as axSpA while 3 patients (1.0%) would be additionally classified as axSpA if only MRI-SI-s was performed. In DESIR, 12 and 10 patients would not be classified axSpA and 3 and 6 patients would be additionally classified axSpA (reader 1 and 2, respectively). Very similar results were found for the presence of fatty lesions or erosions alone (both cut-off of >3).

Conclusion: Replacement of radiographs by assessment of structural lesions on MRI does not lead to a different ASAS axSpA classification in the large majority of patients. These data are promising, however are from two early axSpA cohorts and need to be confirmed in patients with established disease.

	DESIR reader 1	DESIR reader 2	SPACE mean 2/3 readers
Classification remained the same	478	469	275
mNY+ patients with MRI-SI-struct– but remained ASAS+	66	43	3
mNY– patients with MRI-SI-struct+ within ASAS+	23	54	8
ASAS– patients based on mNY– became ASAS+ based on MRI-SI- struct+	3	6	3
ASAS+ patients based on mNY+ became ASAS– based on MRI-SI- struct–	12	10	5
Total	582	582	294

Disclosure: P. Bakker, None; R. van den Berg, None; M. de Hooge, None; Z. Ez-Zaitouni, None; M. van Lunteren, None; K. M. Fagerli, None; R. Ramonda, None; R. B. M. Landewé, None; M. van Oosterhout, None; M. Reijnierse, None; F. van Gaalen, None; P. Claudepierre, None; D. Wendling, None; M. Dougados, None; D. van der Heijde, None.

To cite this abstract in AMA style:

Bakker P, van den Berg R, de Hooge M, Ez-Zaitouni Z, van Lunteren M, Fagerli KM, Ramonda R, Landewé RBM, van Oosterhout M, Reijnierse M, van Gaalen F, Claudepierre P, Wendling D, Dougados M, van der Heijde D. Replacing Radiographic Sacroiliitis By Structural Lesions on MRI of the Sacroiliac Joints in Two Early Axial Spa Cohorts: What Is the Impact on the Classification of Patients According to the ASAS Axial Spa Criteria? [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). https://acrabstracts.org/abstract/replacing-radiographic-sacroiliitis-by-structural-lesions-on-mri-of-the-sacroiliac-joints-in-two-early-axial-spa-cohorts-what-is-the-impact-on-the-classification-of-patients-according-to-the-asas-axi/. Accessed .

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