Ultrasound, MRI, PET, CT, MRA, CTA: guidance here on when to use which imaging technique.
• The European League Against Rheumatism (EULAR) has developed 12 recommendations on how to use imaging for the diagnosis and monitoring of large vessel vasculitis.
• These evidence-based recommendations were arrived at by consensus among experts in the field of rheumatology.
Rationale for development of recommendations
Large vessel vasculitis is a very common form of primary vasculitis, which includes giant cell arteritis (GCA) and Takayasu arteritis (TAK). The increasing role of imaging modalities such as ultrasound necessitates updated recommendations to keep pace with technology and current research.
Christian Dejaco and colleagues across Europe point out, "These advances have brought along significant controversy and uncertainty about when to use which imaging technique, whether imaging might be helpful during follow-up to assess disease activity and damage, and whether imaging results might predict future outcomes."1
Recently, the authors presented the EULAR recommendations for the use of imaging modalities for the diagnosis, monitoring, and outcome prediction of primary large vessel vasculitis in Annals of the Rheumatic Diseases.
The recommendations1. In patients with suspected GCA, an early imaging test is recommended to complement the clinical criteria for diagnosing GCA. Imaging should not delay initiation of treatment.
2. In patients in whom there is a high clinical suspicion of GCA and a positive imaging test, the diagnosis of GCA may be made without an additional test (biopsy or further imaging). In patients with a low clinical probability and a negative imaging result, the diagnosis of GCA can be considered unlikely.
3. Ultrasound of the temporal arteries with or without the axillary arteries is recommended as the first imaging modality in patients with suspected predominantly cranial GCA. A non-compressible "halo" sign is the ultrasound finding most suggestive of GCA.
4. High-resolution MRI of cranial arteries to investigate mural inflammation may be used as an alternative for GCA diagnosis if ultrasound is not available or inconclusive.
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5. CT and positron emission tomography (PET) are not recommended for the assessment of inflammation of cranial arteries.
6. Ultrasound, PET, MRI, and/or CT may be used for detection of mural inflammation and/or luminal changes in extra-cranial arteries to support the diagnosis of large-vessel GCA. Ultrasound is of limited value for assessment of aortitis.
7. In patients with suspected TAK, MRI to investigate mural inflammation and/or luminal changes should be used as the first imaging test to make a diagnosis of TAK, assuming high expertise and prompt availability of the technique.
8. PET, CT, and/or ultrasound may be used as alternative imaging modalities in patients with suspected TAK. Ultrasound is of limited value for assessment of the thoracic aorta.
9. Conventional angiography is not recommended for the diagnosis of GCA or TAK as it has been superseded by the previously mentioned imaging modalities.
10. In patients with large vessel vasculitis (GCA or TAK) in whom a flare is suspected, imaging might be helpful to confirm or exclude it. Imaging is not routinely recommended for patients in clinical and biochemical remission.
11. In patients with large vessel vasculitis (GCA or TAK), magnetic resonance angiography, CT angiography, and/or ultrasound may be used for long-term monitoring of structural damage, particularly to detect stenosis, occlusion, dilatation, and/or aneurysms.
12. Imaging examination should be done by a trained specialist using appropriate equipment, operational procedures, and settings.
Implications for clinicians
• "These recommendations are intended to advise physicians on the use of imaging modalities (including ultrasound, MRI, CT, and PET) when making a clinical diagnosis of large vessel vasculitis and when to apply imaging for monitoring of disease activity and damage."
• These recommendations should not be taken as exhaustive as it is impossible to cover all aspects of large vessel vasculitis in a concise and compact way.
• These recommendations are intended for secondary and tertiary care physicians of all specialties involved in caring for patients with large vessel vasculitis.
1. Dejaco C, Ramiro S, Duftner C, et al. EULAR recommendations for the use of imaging in large vessel vasculitis in clinical practice. Ann Rheum Dis. Epub ahead of print: February 14, 2018. doi:10.1136/ annrheumdis-2017-212649