Virtual surgery. Virtual reality image of a brain (beige), tumour (green) and blood vessels (blue) superimposed on to a patient's head. The patient will undergo surgery to remove the tumour. The 3-D image of the tumour is created from a series of MRI (magnetic resonance imaging) scans of slices through the brain. With the help of contour mapping the virtual image is superimposed onto an image of the patient's head before surgery. Surgeons will thus be able to locate the tumour and important structures before an incision is made. The tumour can thus be removed with the minimum of invasive surgery.