MODEL RELEASED. Angiography. Patient undergoing a coronary (heart) angiography. Angiography is a diagnostic technique used to look at blood flow within blood vessels. A radio-opaque material, often iodine, is injected into the vessels, via a catheter. A machine, known as a fluoroscope (white, circular), then X-rays the area of the body to be studied, and transmits the images to a screen (top left). In this case it is the coronary arteries that are being studied. Angiography is used to diagnose a number of conditions, including stenosis (narrowing of the arteries) and aneurysm (weakness of the blood vessel wall).