Role of imaging in the diagnosis of large and medium-sized vessel vasculitis.

In large-vessel vasculitis, imaging studies are useful to document temporal artery involvement and crucial to show large-vessel involvement. Color Doppler sonography, magnetic resonance, and computed tomography show early vasculitic lesions. Angiography delineates later vascular complications well. Color Doppler sonography, magnetic resonance angiography, and computed tomography angiography can also be used to show vascular luminal changes. Positron emission tomography is very sensitive in detecting large-vessel inflammation. Imaging procedures can also be used to monitor the course of large-vessel vasculitis. In medium-vessel vasculitis, imaging studies can be used to show both vascular changes and internal organ changes.