Fig. 7.

Labeling failure in the left internal carotid artery. There is absence of signal on the ASL perfusion-weighted images (PWI) and corresponding cerebral blood flow (CBF) maps in the arterial territory of the left internal carotid artery. Note the large susceptibility artefact in the area of the left internal carotid area on the T2* weighted (T2*w) image, as the likely cause of the labeling failure. Diffusion weighted imaging (DWI) is normal, supporting interpretation of this finding as an artefact