What noninvasive tests can be used to determine vessel involvement in patients with vasculitis?
• Doppler ultrasound of temporal arteries can localize the area of narrowing in GCA and help determine biopsy sites. “Halo” sign is characteristic of GCA with temporal artery involvement.
• CT angiography can show characteristic features of large- and medium-vessel vasculitis. Not as sensitive as formal angiography.
• Magnetic resonance angiography of the aorta can reveal aortic wall thickening (enhancement with gadolinium indicates inflammation) and areas of stenosis in patients with Takayasu arteritis or GCA with large-artery involvement.
• Positron emission tomography can reveal enhancement of the aortic and subclavian vessel wall if active inflammation occurs in patients with Takayasu arteritis and GCA.