Ultrasound imaging in the diagnosis of large vessel vasculitis.

Nowadays noninvasive vascular imaging has an important role in the diagnostic work-up of the large vessel vasculitides (LVV), most importantly giant cell arteritis (GCA) and Takayasu arteritis. Among the imaging modalities available, ultrasound (US) has several important advantages, including low costs, rapid and repetitive availability without exposure to radiation, and high spatial resolution for assessment of large and medium-sized arteries. Therefore, US can be regarded the first line imaging method in suspected LVV. In patients with suspected GCA, US can replace temporal artery biopsy in certain clinical scenarios, and the application of US early in the diagnostic work-up of suspected GCA in specialized fast track clinics has been suggested to reduce the rate of visual ischaemic complications and associated costs. In other LVV such as Takayasu arteritis and chronic periaortitis, the diagnostic accuracy in comparison to other noninvasive imaging methods has not been formally tested but can be considered to be excellent. However, quality of US is highly dependent on the operator's experience, and assessment of the thoracic aorta which is frequently involved in GCA and TA is limited. The role of US in the follow-up of LVV under treatment is unclear. In view of the promising data supporting its value on the one hand and several uncertainties and controversies on the other hand, the present review article provides a comprehensive overview on current evidence for the application of US in the diagnosis and follow up of LVV. Recent multicentre study results and emerging trends such as the application of compression sonography in the diagnosis of GCA and the use of contrast enhanced ultrasound in disease activity assessment in Takayasu arteritis are discussed.