BIRMINGHAM, ENGLAND – An evidence-based approach coupled with expert consensus has been used to determine the best way to use MRI for the diagnosis of axial spondyloarthritis (axSpA).
Dr. Pedro Machado
Working under the auspices of the British Society for Spondyloarthritis (BRITSpA), a task force of nine rheumatologists and nine musculoskeletal radiologists with an interest in axSpA developed a set of seven recommendations that provide guidance on how to best to acquire and then interpret MRI images of the spine and sacroiliac joints.
The recommendations, which were published online (Rheumatology. 2019 May 2. doi: 10.1093/rheumatology/kez173), cover how to perform MRI when axSpA is suspected, such as by imaging both the sacroiliac joints and the spine, and provide guidance on the sequences and order of MRI planes to be used, and what features may increase the diagnostic confidence of axSpA.
The recommendations are as follows:
• When requesting an MRI for suspected axSpA, imaging of both the sacroiliac joints and the spine is recommended.
• T1-weighted and fat-suppressed, fluid-sensitive sequences are recommended for suspected axSpA.
• The minimum protocol when requesting an MRI for suspected axSpA should include sagittal images of the spine with extended lateral coverage and images of the sacroiliac joints that are in an oblique coronal plane to the joint.
• In the sacroiliac joints, the presence of bone marrow edema, fatty infiltration, or erosion is suggestive of the diagnosis of axSpA. The presence of more than one of these features increases the diagnostic confidence of axSpA.
• In the spine, the presence of multiple corner inflammatory lesions and/or multiple corner fatty lesions increases the diagnostic confidence of axSpA.
• In the sacroiliac joints and/or spine, the presence of characteristic new bone formation increases the diagnostic confidence of axSpA.
• The full range and combination of active and structural lesions of the sacroiliac joints and spine should be taken into account when deciding if the MRI scan is suggestive of axSpA or not.
The recommendations “are intended to standardize practice around the use of MRI,” said Alexis Jones, MBBS, MS (Rheumatology), a senior clinical research fellow at University College London Hospitals NHS Foundation Trust. She presented the recommendations on behalf of the expert task force at the annual conference of the British Society for Rheumatology.
“MRI has become an essential tool in axial spondyloarthritis. It facilitates earlier diagnoses and therefore has allowed for earlier initiation of treatment. It can be used to monitor the burden of inflammation and may predict response to therapy,” Dr. Jones said. Despite this, “there is significant inconsistency in the use of MRI” in clinical practice.
For instance, a survey performed in the United Kingdom (J Rheumatol. 2017;44[6]:780-5) highlighted the need for better collaboration between rheumatology and radiology departments to identify axSpA MRI lesions and develop appropriate protocols.
That survey showed that a quarter of radiologists were not aware of the term axSpA, and just 31% and 25%, respectively, were aware of Assessment of Spondyloarthritis international Society (ASAS) criteria for a positive MRI of the sacroiliac joints and spine. Furthermore, 18% of radiologists did not recognize bone marrow edema as a diagnostic feature of axSpA.
The heterogeneity in the performance of MRI in clinical practice could lead to a delay in diagnosis and potentially misdiagnosis, the task force’s lead author and consultant rheumatologist, Pedro Machado, MD, said in an interview.
“I think everyone has been focusing on demonstrating the value of MRI in the condition but then they forgot to look at the standardization aspect,” said Dr. Machado, who works at University College Hospital and the National Hospital for Neurology and Neurosurgery in London.
With that in mind, the BRITSpA-endorsed task force was set up and met to determine the scope of the recommendations. They looked at the evidence for the use of MRI in the diagnosis of axSpA and used two overarching principles to draft the recommendations: 1) the diagnosis of axSpA is based on clinical, laboratory, and imaging features; 2) Some patients with axSpA have isolated inflammation of the sacroiliac joints or spine.
“All of the recommendations were met with a high level of agreement, indicating a strong consensus” among rheumatologists and radiologists, Dr. Jones noted.
“These recommendations can be immediately applied to clinical practice,” said Dr. Machado, who noted that they should standardize practice and decrease heterogeneity around the use of MRI. “This will help ensure a more informed and consistent approach to the diagnosis of axSpA.”
One of the potential impacts of the recommendations, if followed, is that they may actually help to reduce health care costs, Dr. Machado suggested, because an optimized protocol would be used, making MRI more cost effective by not including sequences that do not add value in the condition.
The next task is to share the recommendations more widely and make sure they are applied in clinical practice.
A systematic literature review on which the recommendations were based was published simultaneously with the conference presentation (Rheumatology. 2019 May 2. doi: 10.1093/rheumatology/kez172).
The work was supported by BRITSpA. The authors had no relevant disclosures.
SOURCE: Bray TJP et al. Rheumatology 2019;58(suppl 3): Abstract 033. doi: 10.1093/rheumatology/kez105.032.