[Imaging of vessels supplying the brain]

Nowadays, several technically validated modalities are available for imaging both the extracranial and intracranial segments of arteries supplying blood to the brain. In the acute stroke setting, computed tomography (CT) angiography is of utmost importance because it provides the key diagnostic criteria indicative for the use of catheter-based recanalization techniques. Ultrasound imaging of extracranial arteries is most suitable for detecting an underlying stenosis of the internal carotid artery (ICA) in patients with stroke, transient ischemic attacks (TIA), retinal vessel occlusion and amaurosis fugax. Ultrasound imaging enables measurement of the methodologically most reliable criteria for grading stenosis of the ICA, which defines the indications for revascularization procedures in this territory. Magnetic resonance imaging (MRI) in the cross-sectional mode is of greatest value in confirming or excluding an arterial dissection even in short arterial segments, whereas MR angiography generates a more global view of the cerebral circulation. In most cases classical digital subtraction angiography (DSA) is no longer needed for diagnostic purposes only. Conversely, it is an indispensable component of any interventional approach and thus of growing importance. Ultrasound imaging is not indicated for the clarification of vertigo or syncope. In addition, there is no evidence that ultrasound screening of the ICA adds any value to the care of asymptomatic persons.