Fig. 1.

A guide to VE-ASL dynamic angiography. (a) Labelling in the neck and the associated encoding matrix for four arteries (right and left internal carotids, right and left vertebrals) plus static tissue contribution. In conventional ASL all the arteries are either in the control or labelled condition. In VE-ASL the labelling is modulated to put a subset in control whilst the others are labelled. Ideally arteries will be either fully labelled or controlled, but in practice it may not be possible to achieve this and in some acquisitions arteries will be partially labelled. (b) Example VE-ASL angiographic images in the brain showing raw image (dominated by static tissue contribution) and result after subtraction from the control image.