Fig. 2
From: A visual quality control scale for clinical arterial spin labeling images
Cerebral blood flow images containing examples of artifacts: a motion artifacts are observed as pseudo-perfusion hyperintensity rings (red arrows), b signal drop in the inferior orbitofrontal region (green arrows), c geometric anterior-posterior distortion (red arrows), d bright spots depicting macro-vascular artifacts from the posterior cerebral artery behind the thalamus (1) and in the cortex (2, green arrows). Note that the 0 signal drop image is a 3D spiral image, for a better contrast on how the inferior orbitofrontal perfusion should appear without signal drop.