Investigations in systemic vasculitis - The role of imaging.

Imaging plays an increasing role for confirming a suspected diagnosis of giant cell arteritis (GCA) or Takayasu arteritis (TAK). Ultrasound, magnetic resonance imaging (MRI), and computed tomography demonstrate a homogeneous, most commonly concentric, arterial wall thickening. 18F-Fluorodeoxyglucose (FDG) positron emission tomography (PET) displays increased FDG uptake of inflamed artery walls delineating increased metabolism. Ultrasound and MRI are recommended to be the initial imaging modalities in cranial GCA and TAK, respectively. Extracranial disease can be confirmed by all four modalities, particularly by PET in case of inflammation of unknown origin. If the diagnosis remains uncertain, additional investigations including biopsy and/or additional imaging are recommended. Imaging should be performed by a trained specialist using appropriate operational procedures and settings with appropriate equipment. Further research is necessary on the role of imaging for disease monitoring. This review will discuss advantages and disadvantages of imaging modalities in the diagnosis of vasculitis.