Bray, TJP

Hall-Craggs, MA

Jones, A

Machado, PM

Marzo-Ortega, H

English

UCL Discovery

Comment on: Recommendations for acquisition and interpretation of MRI of the spine and sacroiliac joints in the diagnosis of axial spondyloarthritis in the UK: reply  Margaret A Hall-Craggs1, Timothy JP Bray1, Alexis Jones2, Helena Marzo-Ortega3,4, Pedro M Machado2,5,6  1Centre for Medical Imaging, University College London, London, UK 2Department of Rheumatology, University College London Hospitals NHS Foundation Trust, London, UK 3NIHR Leeds Biomedical Research Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK 4Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UK 5Department of Rheumatology, Northwick Park Hospital, London North West University Healthcare NHS trust, London, UK 6Centre for Rheumatology and MRC Centre for Neuromuscular Diseases, University College London, London, UK  Correspondence to: Pedro M Machado University College London 1st Floor, Russell Square House 10-12 Russell Square, WC1B 5EH London  Email: p.machado@ucl.ac.uk   Dear Editor, we thank the authors(1) for their interest in our recent paper on the recommendations for acquisition and interpretation of MRI of the spine and sacroiliac joints in patients suspected of having of axial spondyloarthritis (axSpA).(2) These recommendations were formulated following a systematic review of the literature(3) and agreement amongst a multidisciplinary expert group of rheumatologists and radiologists.   We read the cases presented by the authors of this letter with interest. We believe they are atypical for axSpA, clinically and/or radiologically. The cardinal MRI features of axSpA are of subchondral bone marrow oedema/osteitis, enthesitis and erosions, with sclerosis and subcortical fat metaplasia occurring during healing phases, followed ultimately by bone ankylosis. However, even these appearances cannot be taken as diagnostic in the absence of relevant clinical symptomatology. It is important to highlight that clinical history in axSpA is variable and the diagnosis is based on pattern recognition of a combination of features. These may include inflammatory back pain and stiffness, peripheral manifestations (arthritis, dactylitis, enthesitis and tenosynovitis), restriction of spinal mobility and extra-articular manifestations (uveitis, psoriasis and inflammatory bowel disease). It is part of the routine clinical work up to inquire about other clinical features that may suggest an alternative diagnosis, such as history of trauma, surgery, radiculopathy, chronic widespread pain, osteoporosis, fractures, infection, and connective tissue disease symptoms.(4) Osteoid osteomas typically present during the second decade with progressively increasing pain that is more severe at night, may or may not be related to activity, and is characteristically highly responsive to non-steroidal anti-inflammatory drugs (NSAIDs), usually within less than half an hour.(5) This clinical presentation shares some similarities with axSpA. Imaging appearances however, can be distinctive as shown in the images provided, where bone marrow oedema appears as intraosseous rather than in a subcortical distribution as seen in axSpA. This image therefore is not a typical mimic of axSpA sacroiliitis. In cases such as the one presented, there is general agreement that where osteoid osteomas are suspected, enhancement may be helpful, but that high resolution CT scanning is the key diagnostic tool.(5, 6)  In the second case, the imaging appearances are of a septic arthritis, with the pathology focused on the joint space. There is also extensive surrounding soft tissue oedema. Again, these appearances should not be considered a mimic of axSpA sacroiliitis, which being primarily an osteitis, does not evoke surrounding soft tissue changes even when very acute. Very early septic sacroiliitis could mimic unilateral sacroiliitis radiologically but the clinical history is distinctive. The imaging appearances are then of subcortical bone marrow oedema and increased T2 signal in the joint space, but enhancement of the joint and subcortical bone would not differentiate between these conditions. It is the clinical context and symptoms, together with serological findings including leukocytosis and neutrophilia, that are more likely to help distinguish these disease processes, rather than enhancement per se. SIJ MRI is a valuable tool in the workup of patients with chronic back pain suspected to have axSpA. However, it does not replace careful clinical evaluation and differential diagnostic considerations, including not only clinical and laboratory features but also demographic and activity related considerations such as age, body mass index, profession, epidemiological context and level of sport activity. Furthermore, contextual interpretation of active and structural MRI lesions simultaneously is key to differentiate axSpA sacroiliitis from other conditions. The literature supporting the use of non-contrast enhanced scans where axSpA related sacroiliitis is suspected is highly persuasive.(7-9) Our recommendations do not cover the imaging of other conditions that occur in the sacrum, posterior ilia or the sacroiliac joints. However, as outlined above, in general careful scrutiny of the unenhanced images will show that the appearances of these conditions are not ‘mimics’ of axSpA sacroiliitis. Further, good communication between rheumatologists, physicians and radiologists should support consensus diagnosis in the clinical setting.      Acknowledgements Margaret A Hall-Craggs and Pedro M Machado and are supported by the National Institute for Health Research (NIHR) University College London Hospitals (UCLH) Biomedical Research Centre (BRC). Helena Marzo-Ortega is supported by the NIHR Leeds BRC. The views expressed are those of the authors and not necessarily those of the (UK) National Health Service (NHS), the NIHR, or the (UK) Department of Health.  Disclosures The British Society for Spondyloarthritis (BRITSpA) is a registered charity in England and Wales. H.M.O. has received grants and/or honoraria from Abbvie, Celgene, Eli-Lilly, Janssen, MSD, Novartis, Pfizer and UCB. P.M.M. has received consulting/speaker’s fees from Abbvie, BMS, Celgene, Janssen, MSD, Novartis, Pfizer, Roche and UCB. The other authors have declared no conflicts of interest.  References 1. Corrêa DG, C. C, Costa FM, Mendonça S, Marchiori E. Comment on: Recommendations for acquisition and interpretation of MRI of the spine and sacroiliac joints in the diagnosis of axial spondyloarthritis in the UK. Rheumatology (Oxford). 2019;[In Press]. 2. Bray TJP, Jones A, Bennett AN, Conaghan PG, Grainger A, Hodgson R, et al. Recommendations for acquisition and interpretation of MRI of the spine and sacroiliac joints in the diagnosis of axial spondyloarthritis in the UK. Rheumatology (Oxford). 2019. 3. Jones A, Bray TJP, Mandl P, Hall-Craggs MA, Marzo-Ortega H, Machado PM. Performance of magnetic resonance imaging in the diagnosis of axial spondyloarthritis: a systematic literature review. Rheumatology (Oxford). 2019. 4. Carvalho PD, Machado PM. How to investigate: Early axial spondyloarthritis. Best Practice & Research Clinical Rheumatology. 2019; https://doi.org/10.1016/j.berh.2019.07.00 (In Press). 5. May CJ, Bixby SD, Anderson ME, Kim YJ, Yen YM, Millis MB, et al. Osteoid Osteoma About the Hip in Children and Adolescents. J Bone Joint Surg Am. 2019;101(6):486-93. 6. Assoun J, Richardi G, Railhac JJ, Baunin C, Fajadet P, Giron J, et al. Osteoid osteoma: MR imaging versus CT. Radiology. 1994;191(1):217-23. 7. Hermann KG, Landewe RB, Braun J, van der Heijde DM. Magnetic resonance imaging of inflammatory lesions in the spine in ankylosing spondylitis clinical trials: is paramagnetic contrast medium necessary? J Rheumatol. 2005;32(10):2056-60. 8. de Hooge M, van den Berg R, Navarro-Compan V, van Gaalen F, van der Heijde D, Huizinga T, et al. Magnetic resonance imaging of the sacroiliac joints in the early detection of spondyloarthritis: no added value of gadolinium compared with short tau inversion recovery sequence. Rheumatology (Oxford). 2013;52(7):1220-4. 9. van Onna M, van Tubergen A, van der Heijde D, Jurik AG, Landewe R. Gadolinium contrast-enhanced MRI sequence does not have an incremental value in the assessment of sacroiliitis in patients with early inflammatory back pain by using MRI in combination with pelvic radiographs: a 2-year follow-up study. Clin Exp Rheumatol. 2014;32(2):225-30.  

Comment on: Recommendations for acquisition and interpretation of MRI of the spine and sacroiliac joints in the diagnosis of axial spondyloarthritis in the UK: reply

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Comment on: Recommendations for acquisition and interpretation of MRI of the spine and sacroiliac joints in the diagnosis of axial spondyloarthritis in the UK: reply

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