Coloured computed tomography (CT) scan of the liver of a patient undergoing trans arterial chemoembolisation (TACE). In this procedure anticancer drugs and an occluding agent are delivered directly to a liver tumour via a catheter. The catheter enters a blood vessel in the groin and is threaded through to the hepatic (liver) artery and the blood vessels feed the tumour. The anticancer drugs kill cancerous cells and the occluding agents block the blood flow to the tumour, starving it of nutrients. TACE is used to shrink tumours so that they can be operated on, or as a palliative treatment.