angiography

Angiography

Creating a road map of vessels
for diagnosis and treatment

Interventional radiologists can produce images of arteries and other blood vessels or areas of blood accumulation by injecting contrast agent into the blood stream (to make blood, and thus blood vessels, more visible radiologically) and then using x-rays or other imaging modalities to show the blood pathways. They use this approach to createimages of circulation and circulatory pathways in and around the head, neck, aorta, lung, kidneys, liver, legs, and other areas. Angiography is one of the most important services in the interventional radiology field. It gives specialists a special type of image called an arteriogram (or angiogram), which serves as a kind of roadmap of blood vessels. (Also venogram, when imaging veins rather than arteries. See box.)

Angiograms are one of the most indispensable forms of radiologic imaging –– essential to screening, prevention, diagnosis, and care of all types of vascular conditions.

This angiography capability permits specialists to detect blockages, aneurysms, narrowed areas, perforations, growths, malformations, and other abnormalities in blood vessels. The procedure is critical in treating vascular disease (including stroke), cancer, and other major types of health conditions. Cardiologists use the same approach in the cardiac catheterization laboratory to image coronary arteries.

The procedures are painless to undergo, usually require sedation only and local anesthesia, and can be performed on an outpatient basis. The imaging team will place a catheter, through a small cut in the skin, into a primary artery responsible for the blood supply to the area of study, then inject the dye or contrast material. To produce the angiogram, radiologists may use a special type of x-ray imaging called fluoroscopy, which allows them to see images of blood vessels during the procedure, for a longer period of time, and repeatedly.

Venography

Venography is a form of angiography used to view venous blood supply and the shape of veins in the body. The principle of using x-raying imaging and injecting contrast agents to reveal the shape of the veins is the same as when assessing arteries with angiography.

Venography images are called venograms, and they are import, for example, in determining whether veins have become swollen and distended from varicosing. In this application, specialists use them to evaluate veins in the legs and arms, was well as the veins that drain blood from the kidneys or ovaries.

More recently, radiologists have also been able to perform angiography using CT scanning and MR imaging. A magnetic resonance or computed tomography angiogram can often produce a level of detail that radiologists cannot obtain from other imaging techniques. These approaches are easier to undergo than conventional angioplasty, in part because there is no need to place a catheter in a large artery or vein. The contrast material can be injected or infused into a smaller, peripheral artery. Magnetic resonance angiography (MRA) can also be performed without use of contrast material. The radiologic team can often reconstruct angiograms into three-dimensional images.

Recently, the specialists have also been using an important new angiographic technique in which they obtain fluoroscopic images from CT studies. CT fluoroscopy permits the team to produce more images, and in three dimensions, in spaces where the specialists have injected or infused contrast agent. Patients receive less total radiation than they do from CT or fluoroscopy alone, and the interventional team gains greater precision in analyzing the images and anatomy of targeted areas. This type of study is very helpful for planning and performing procedures, and the radiology team can use it continuously during interventions or intermittently between steps. The technique saves time because the team can directly visualize needles, catheters, and other probes. Thus, this capability allows for more accurate placement of these instruments, as well as quicker procedure times.

Among important examples of specific applications, angiography can be used to:

• identify blot clots in arteries around the lungs or in the large veins of the pelvis or legs;

• look for narrowing of arteries around the kidney, a condition that can cause high blood pressure;

• locate weakened, bulging areas (aneurysms) in the walls of major vessels, which can cause sudden, life-threatening events when they rupture, or identify disruptions (dissections) of the aorta;

• find narrowed areas in the femoral arteries, which can cause pain and weakness in the legs;

• detect atherosclerosis in the carotid arteries of the neck or aneurysms in the brain, both of which can lead to stroke;

• demonstrate a source of bleeding, including in the digestive system from such sources as a stomach ulcer or ruptured blood vessel;

• assess the extensiveness and blood supply of tumors, in such areas as the gastrointestinal tract or liver;

• and evaluate that status of a stent , placed to maintain the opening of a vessel.

Surgeons may use angiograms to determine if surgery is required and to plan the operation. The images can also reveal whether vessel dilation , stent placement , or other nonsurgical interventions are indicated. The interventional radiologist can perform these steps at the time the angiogram is performed, if performing catheter angiography. Treatments can also take the form of thrombolysis or embolization .