MRI should now be the first imaging test ordered for suspected axial spondyloarthritis, replacing plain radiography, under updated EULAR recommendations.

The revised guidance, the first update since 2015, introduces three new overarching principles and updates nine existing recommendations on imaging in the diagnosis and management of spondyloarthritis.

Professor Peter Mandl of the Medical University of Vienna presented the changes, which mark a significant shift away from radiography as the default initial test. MRI of the sacroiliac joints is now the recommended first-line modality for suspected axSpA. MRI of the spine can also be performed where regional spinal symptoms are present, as it may provide additional differential diagnostic information.

When MRI is unavailable or contraindicated, radiography or, preferably, low-dose CT can be used to assess the sacroiliac joints.

For disease monitoring, MRI can assess both inflammatory activity and structural damage in the sacroiliac joints and spine. Radiography remains an option for long-term monitoring of structural spinal damage, and low-dose CT can provide additional information on structural damage in the sacroiliac joints and spine.

For peripheral spondyloarthritis, ultrasound and MRI remain the preferred modalities for diagnosis. Both are now recommended alongside radiography for monitoring structural damage in peripheral SpA.

Updated ASAS/SPARTAN classification criteria also centre on MRI

The first major revision of the ASAS classification criteria for axSpA since 2009 similarly puts imaging at the centre of diagnosis.

Developed jointly by ASAS and SPARTAN from data in the international CLASSIC study, the updated criteria were derived from an analysis of 1,015 patients referred to rheumatologists with undiagnosed back pain suggestive of axSpA. Clinical, biological and imaging features were assessed against the treating rheumatologist’s diagnosis.

MRI of the sacroiliac joints showing both inflammatory and structural lesions had the strongest association with an axSpA diagnosis.

The revised criteria also incorporate:

• HLA-B27 positivity
• Elevated C-reactive protein
• Inflammatory back pain
• Inflammatory bowel disease
• Acute anterior uveitis
• Heel enthesitis
• Psoriasis

In the validation dataset, the final criteria achieved a sensitivity of 79.5% and a specificity of 90.4%.

The update was presented by Professor Walter P. Maksymowych of the University of Alberta, Canada.