Cerebral arteriovenous malformation. Magnetic resonance angiogram (MRA) scan of a coronal section of the brain of a 28-year-old patient with an arteriovenous malformation (AVM, upper centre, white). This is a large AVM in the parieto-occipital region of the left cerebral hemisphere of the patient's brain. An AVM is an abnormal blood vessel arrangement which affects the connecting vessels between arteries and veins. Health risks resulting from a cerebral AVM include haemorrhage, stroke, or cell death. This is a MRA scan which highlights blood vessels by the injection of a contrast medium.