Angiography or arteriography is a medical imaging technique in which an X-ray picture is taken to visualize the inner opening of blood filled structures, including arteries, veins and the heart chambers. Its name comes from the Greek words angeion, "vessel", and graphien, "to write or record". The X-ray film or image of the blood vessels is called an angiograph, or more commonly, an angiogram.
The Portuguese physician and neurologist Egas Moniz, Nobel Prize winner in 1949, developed in 1927 the technique of contrasted x-ray cerebral angiography to diagnose several kinds of nervous diseases, such as tumors and arteriovenous malformations. He is usually recognised as one of the pioneers in this field. With the introduction of the Seldinger technique in 1953, the procedure became markedly safer as no sharp introductory devices needed to remain inside the vascular lumen.
Angiograms require the insertion of a catheter into a peripheral artery, e.g. the femoral artery.
As blood has the same radiodensity as the surrounding tissues, a radiocontrast agent (which absorbs X-rays) is added to the blood to make angiography visualization possible. The angiographic X-ray image shows shadows of the openings within the cardiovascular structures carrying blood (actually the radiocontrast agent within). The blood vessels or heart chambers themselves remain largely to totally invisible on the X-ray image.
The X-ray images may be taken as either still images, displayed on a fluoroscope or film, useful for mapping an area. Alternatively, they may be motion images, usually taken at 30 frames per second, which also show the speed of blood (actually the speed of radiocontrast within the blood) traveling within the blood vessel.
The most common angiogram performed is to visualize the blood in the coronary arteries. A long, thin, flexible tube called a catheter is used so as to administer the radiocontrast agent at the desired area to be visualized. The catheter is threaded into an artery in the groin or forearm, and the tip is advanced through the arterial system into one of the two major coronary arteries. X-ray images of the transient radiocontrast distribution within the blood flowing within the coronary arteries allows visualization of the size of the artery openings. Presence or absence of atherosclerosis or atheroma within the walls of the arteries cannot be clearly determined. See coronary catheterization for more detail.
Angiography is also commonly performed to identify vessel narrowing in patients with retinal vascular disorders, such as diabetic retinopathy and macular degeneration.
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