What is the best initial imaging choice for diagnosing vasculitis (inflammation of blood vessels)?

From the Guidelines

The best initial imaging choice for diagnosing vasculitis is ultrasound, as recommended by the most recent guidelines for large vessel vasculitis. According to the 2023 update on the use of imaging in large vessel vasculitis in clinical practice 1, ultrasound is now recommended as the first-line imaging test in all patients with suspected giant cell arteritis, and axillary arteries should be included in the standard examination. This recommendation is based on the latest evidence and prioritizes the use of non-invasive and widely available imaging modalities.

Key Considerations

• For large vessel vasculitis, such as giant cell arteritis or Takayasu arteritis, ultrasound is the preferred initial imaging modality, with MRI or FDG-PET as alternative options 1.
• The choice of imaging modality should be individualized based on the patient's clinical presentation, suspected vessel involvement, and local expertise.
• Ultrasound may be useful as a screening tool for certain types of vasculitis, particularly temporal arteritis, but lacks the comprehensive assessment provided by cross-sectional imaging.

Imaging Modalities

• Ultrasound: recommended as the first-line imaging test for suspected giant cell arteritis 1.
• MRI: can be used as an alternative to ultrasound for examining cranial and extracranial arteries 1.
• FDG-PET: can be used as an alternative to ultrasound for examining cranial and extracranial arteries, and for assessing vessel abnormalities in patients with suspected relapse 1.
• CT: can be used as an alternative to MRI or FDG-PET for assessing vessel abnormalities in patients with suspected relapse 1.

Clinical Context

• The diagnosis of vasculitis often relies on a combination of clinical presentation, laboratory findings, and imaging results.
• The choice of imaging modality should be guided by the suspected type and location of vasculitis, as well as the patient's individual characteristics and clinical context.
• The latest guidelines and evidence should be consulted to ensure that the most appropriate imaging modality is selected for each patient.

From the Research

Imaging Modalities for Vasculitis

The best initial imaging choice for diagnosing vasculitis depends on the type of vasculitis and the affected blood vessels. The following imaging modalities are commonly used:

• Ultrasound: useful for detecting abnormalities in temporal and axillary arteries, particularly in large-vessel vasculitides such as giant cell arteritis (GCA) and Takayasu arteritis (TA) 2, 3
• Magnetic Resonance Imaging (MRI): recommended for suspected Takayasu's arteritis, and useful for detecting wall abnormalities in temporal and occipital arteries 2, 4
• Computed Tomography (CT): useful for detecting aneurysms and stenoses, and for evaluating extracranial large vessel vasculitis 2, 5
• Positron Emission Tomography (PET): useful for detecting increased metabolic activity in inflamed artery walls, particularly in GCA and TA 2, 5
• Color-coded duplex sonography: considered the first choice imaging test in suspected giant cell arteritis 4

Specific Imaging Recommendations

For giant cell arteritis (GCA), ultrasound and MRI are recommended imaging techniques 2, 4. For Takayasu arteritis (TA), MRI and CT are useful for detecting wall abnormalities and aneurysms 2, 5. In patients with a high suspicion of GCA who present with visual disturbances, initiation of high-dose intravenous corticosteroids should not be delayed by imaging 2.

Imaging Findings

Imaging studies can reveal characteristic findings in vasculitis, including:

• Homogeneous, concentric thickening of the arterial wall 2, 5
• Aneurysms and stenoses 2, 5
• Increased FDG uptake in inflamed artery walls 2, 5
• Wall swelling of temporal arteries, which disappears after 2-3 weeks of glucocorticoid treatment 3