Brain arteries. Rotating view of a 3D magnetic resonance angiography (MRA) volume-rendered scan of the major intra-cranial arterial blood vessels (orange) of the human brain. This side view starts with the front of the brain at left, with the brain then rotated horizontally 360 degrees from left to right. MRA is a magnetic resonance imaging (MRI) technique that highlights blood vessels, usually by the use of injected contrast agents that make the blood vessels more visible on the MRI scans.