Practice Essentials
Giant cell arteritis is a systemic obliterative vasculitis mainly involving the arteries that originate from the arch of the aorta. However, any vessel in the body can be affected. The inflammation is a necrotizing obliterative vasculitis of large and medium-sized vessels. [1] The superficial temporal, vertebral, ophthalmic, and posterior ciliary arteries are more commonly affected than the internal and external carotid arteries. Intracranial arteries other than those involving the orbits are less commonly affected. Cases involving the proximal distal aorta and the subclavian and abdominal arteries have been reported. The inflammation is segmental, and therefore, skip lesions are seen. [2]
Giant cell arteritis is a disease of elderly persons, the incidence of which increases with increasing age. The mean age of onset is 70 years.
Preferred examination
Color Doppler ultrasonography is a method of assessing blood flow qualitatively and quantitatively. In the presence of arteritis, the sonograms show a hypoechoic halo due to edema of the arterial wall. [3] A systematic review and meta-analysis found that, compared with a clinical diagnosis of giant cell arteritis, the ‘halo’ sign at temporal arteries (8 studies, 605 patients) had a pooled sensitivity of 77% (95% CI, 62% to 87%) and specificity of 96% (95% CI, 62% to 87%). [4]
The presence of a halo sign is a criterion used to diagnose giant cell arteritis with color Doppler ultrasonography. However, the sign is not seen in all patients, and it may also be seen in healthy persons. The halo has also been reported in polyarteritis nodosa. Therefore, the criterion standard is the temporal artery biopsy.
The advantages of color Doppler ultrasound are that it is simple, it is noninvasive, and it can be used to examine several vessels, superficial and deep. Another advantage of this technique is that follow-up scans can be obtained to assess the response to steroids. The hypoechoic shadow becomes mid-echoic in about 2 weeks. With fibrosis, the shadow becomes hyperechoic. [5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
Other nonradiologic investigations include a determination of the blood sedimentation rate and temporal artery biopsy (see the images below). [16]
CT and MRI are not useful in diagnosing giant cell arteritis; however, they may be used to diagnose complications due to giant cell arteritis, such as stroke.
Giant cell arteritis. Low-power view of a temporal artery biopsy sample shows giant cell arteritis.
Giant cell arteritis. High-power view shows disruption of the intima with a collection of multinucleated giant cells.
For patient education information, see Temporal Arteritis.
EULAR guidelines
European League Against Rheumatism (EULAR) guidelines, published in 2018, include the following recommendations on imaging in giant cell arteritis (GCA) [17] :
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In patients with suspected GCA, early imaging is recommended to complement the clinical diagnostic criteria, assuming high expertise and prompt availability of the imaging technique. Imaging should not delay initiation of treatment.
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In patients in whom there is a high clinical suspicion of GCA and a positive imaging study, the diagnosis of GCA may be made without biopsy or further imaging. In patients with a low clinical probability and a negative imaging result, the diagnosis of GCA can be considered unlikely. In all other situations, additional efforts toward a diagnosis are necessary.
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Temporal artery ultrasound (US), with or without axillary artery US, is recommended as the first imaging modality in patients with suspected GCA with predominantly cranial manifestations (eg, headache, visual symptoms, jaw claudication, temporal artery swelling and/or tenderness). A non-compressible ‘halo’ sign is the US finding most suggestive of GCA.
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If US is not available or the results are inconclusive, high-resolution MRI of cranial arteries to investigate mural inflammation may be used as an alternative for diagnosis of GCA.
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CT and PET are not recommended for the assessment of inflammation of cranial arteries.
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US, PET, MRI, and/or CT may be used for detection of mural inflammation and/or luminal changes in extracranial arteries to support the diagnosis of large-vessel GCA. US is of limited value for assessment of aortitis.
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Conventional angiography is not recommended for the diagnosis of GCA, as it has been superseded by the previously mentioned imaging modalities.
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In patients with GCA 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.
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MRA, CTA, and/or US may be used for long-term monitoring of structural damage in patients with GCA, particularly to detect stenosis, occlusion, dilatation, and/or aneurysms. The frequency of screening as well as the imaging method applied should be decided on an individual basis.
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Imaging examination should be done by a trained specialist using appropriate equipment, operational procedures, and settings. The reliability of imaging, which has often been a concern, can be improved by specific training.
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Giant cell arteritis. Low-power view of a temporal artery biopsy sample shows giant cell arteritis.
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Giant cell arteritis. Low-power view of a normal temporal artery biopsy sample.
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Giant cell arteritis. High-power view shows disruption of the intima with a collection of multinucleated giant cells.
