Imaging in vasculitis.

Vasculitides may involve small, medium-sized or large arteries. In small-vessel vasculitides imaging studies of lungs, nasal sinuses, cerebrum, heart and other organs are important for determining disease extension and disease activity. Aneurysms are a hallmark of medium-sized artery vasculitides. In large-vessel vasculitis, imaging studies depict homogeneous, circumferential wall swelling and smoothly tapered luminal narrowing. Ultrasound and high-resolution magnetic resonance imaging (MRI) show characteristic wall abnormalities in temporal and occipital arteries whereas ultrasound, MRI, MR angiography, computed tomography (CT), CT angiography and positron emission tomography delineate characteristic features in extra-cranial arteries that are affected in large-vessel giant cell arteritis, Takayasu arteritis and idiopathic aortitis. Conventional angiography has still its place for therapeutic interventions. Imaging has led to a better understanding of the nature and distribution of vasculitides. It significantly facilitates diagnosis of patients with suspected vasculitis.