Brain tumour. Computer artwork of nerve pathways (coloured) in a brain with a tumour (white/red, upper right). The brain is seen from the front. Brain tumours can be benign or malignant (cancerous). They can cause seizures, headaches, and memory and personality changes due to the growth of the tumour. This artwork shows the fibres as they would appear using 3D diffusion tensor imaging (DTI) magnetic resonance imaging (MRI). This technique, also called tractography, measures the direction of water diffusion, which in the brain reveals the orientation of nerve fibres.