Angiography

Angiography is a procedure performed to obtain diagnostic information about the

blood vessels

that carry blood to various parts of the body, particularly whether the vessel is

blocked

by a

blood clot

or have

narrowed

. Traditionally, this is done by injecting a harmless dye that is radiopaque (does not allow X-rays to penetrate) so the blood vessels can be outlined on X-rays or other imaging techniques. Depending on the type of

angiogram

(X-ray) required, access to the blood vessels is usually gained through the larger arteries, such as in the arm or groin. A catheter (thin, flexible tube) is passed through an artery to the required site and the dye is released into the bloodstream. An X-ray or image is then taken.