Brain tumour. Coloured 3-D magnetic resonance imaging (MRI) scan of a patient's head and brain showing a brain tumour (green). Here, the blood vessels are red and brain ventricle is cyan. This 3-D image was created from a series of MRI slice images through the brain. It will be used in 3-D virtual reality assisted surgery to help plan and execute the removal of the tumour. The image will be superimposed onto a video image of the patient's head. This allows the surgeon to locate the brain tumour in relation to other important brain tissue before surgery begins. The tumour can thus be removed with minimum damage to the brain.