iant cell arteritis (GCA) is a primary systemic vasculitis involving the large- and medium-sized arteries, particularly the temporal arteries. Imaging studies have proved useful to detect inflammatory changes in the temporal arteries, and are invaluable in demonstrating inflammation in large arteries, which are not easily accessible to biopsy. Color-Doppler sonography (CDS), magnetic resonance (MR) angiography (MRA) and contrast-enhanced computerized tomography (CT) angiography (CTA) can visualize both the arterial wall and the lumen. All these techniques can aid in diagnosing early arteritis by demonstrating inflammation of the arterial wall even before vascular complications such as stenoses and aneurysms develop. Precocious inflammatory signs of arteritis include vessel wall thickening and transmural edema, which shows as a hypoechoic “halo” surrounding the lumen of an inflamed artery on CDS and as contrast enhancement on MRA and CTA. CDS is particularly suited to investigate the superficial arteries (including the temporal arteries), while CT and MR are able to depict well deep, large vessels such as the thoracic and abdominal aorta, which can hardly or not be visualized by CDS. Alternatively, large-vessel inflammation can be assessed by 18F-Fluorodeoxyglucose positron emission tomography (PET). However, PET cannot demonstrate changes in the temporal or renal arteries. Moreover, PET is unable to delineate the anatomical details of the arterial wall, and is thus not helpful in detecting stenoses or aneurysms. For monitoring purposes, CDS, MRI/MRA, and CT/CTA are helpful in that they can demonstrate both arterial wall and lumen changes. PET can also be used to monitor the extent and intensity of vascular inflammation in large vessels. Digital subtraction angiography has now been largely superseded by CTA or MRA, but may still have a role in guiding interventional procedures.
Disclosure of Interest None declared
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