Fig 5. Right vertebral artery dissection with a pseudoaneurysm seen on CTA, which is not visualized on MR imaging/MRA. A, Curved planar reformatted image from CTA of the distal right vertebral artery demonstrates irregularity (arrow) as well as a small distal pseudoaneurysm. B, An axial CTA source image shows contrast within the true lumen and the pseudoaneurysm anteriorly (arrow). C, Contrast-enhanced MRA demonstrates the irregularity associated with the dissection, but not the pseudoaneurysm. D, 2D time-of-flight MRA depicts the narrowed true lumen but does not show the pseudoaneurysm, presumably due to saturation of slow-flowing blood.