3-D virtual reality assisted surgery. Brain surgeon using an adapted MRI (magnetic resonance imaging) scanner to perform surgery to remove a tumour. He is aided by 3-D virtual reality (VR). On the monitor (at upper centre) is a 3-D VR model of the patient's brain. It shows internal structures of the brain in relation to the tumour (green). The image was computer generated from several MRI slice images through the brain. During surgery new MRI scans are taken so that the VR model can be adjusted to locate the precise place of the tumour. The tumour can thus be removed with the minimum of invasive surgery. Surgery at the Brigham and Women's Hospital, USA.