Angiography

An imaging procedure that enables blood vessels to be seen clearly on X-ray film following the injection of a contrast medium (a substance that is opaque to X-rays). Angiography is used to detect conditions that alter the appearance of blood vessels, such as aneurysm, and narrowing or blockage of blood vessels by atherosclerosis, or by a thrombus or embolus. It is also used to detect changes in the pattern of blood vessels that supply organs injured or affected by a tumour. Carotid angiography (of the arteries in the neck) may be used to investigate transient ischaemic attacks. Cerebral angiography can be used to detect an aneurysm in the brain or pinpoint the position of a brain tumour. Coronary angiography, often combined with cardiac catheterization, can identify the sites of narrowing or blockage in coronary artery disease. Digital subtraction angiography uses computer techniques to process images and remove unwanted background information. Angiographic techniques have been adapted to allow certain treatments that, in some cases, eliminate the need for surgery (see angioplasty, balloon; embolization). (See also aortography.)