Coloured diffusion magnetic resonance imaging (MRI) scan of the brain of a 44 year old male patient with a large lesion in the left temporoparietal region. The lesion is probably a glioblastoma, a malignant (cancerous) tumour that arises from the supporting glial cells in the brain. Diffusion MRI shows blood flow in the brain. Areas of low blood flow (mainly within the tumour) are blue, areas of normal blood flow are yellow and orange, and areas of high blood flow are red.