Diagnostic imaging in Takayasu arteritis.

Abstract

New imaging modalities may help accurately diagnose and monitor Takayasu arteritis (TAK). Examination of the published literature on arterial imaging studies other than conventional angiography will help guide appropriate use of these studies in TAK. MRI, magnetic resonance angiography (MRA), Doppler ultrasound, CT, and positron emission tomography (PET) are all potentially useful for evaluation of TAK. MRI/A avoids the risks of arterial puncture, iodinated contrast load, and radiation exposure, while providing information on arterial wall anatomy and obtaining a generalized arterial survey in TAK. Ultrasound can be helpful in detecting sub-millimeter changes in wall thickness of the carotid arteries and in differentiating TAK from atherosclerotic disease based on minimal plaque content, concentric and long segmental involvement, and location of lesion. Like MRI, CT angiography can be used to detect areas of aortic wall thickening and obtain a generalized survey of the aorta and its proximal branches for areas of stenosis and without the risks associated with arterial puncture. However, CT provides less detailed resolution than ultrasound and incurs the risks of contrast administration. Finally, PET scanning may provide valuable information about cellular activity within an inflamed arterial wall before morphologic changes on other imaging studies. Although it is still unclear how often early arterial wall changes lead to stenotic lesions, use of these modalities in combination, for both routine monitoring and evaluation of new symptoms, may facilitate the detection of TAK disease activity at a more treatable stage.