Angiography is a minimally invasive medical test that helps physicians diagnose and treat medical conditions. Angiography uses one of three imaging technologies and, in some cases, a contrast material to produce pictures of major blood vessels throughout the body.
Angiography is performed using:
- X-rays with catheters
- Computed tomography (CT)
- Magnetic resonance imaging (MRI)
- CT imaging uses special x-ray equipment to produce multiple images and a computer to join them together in multidimensional views. In CT angiography (CTA), computed tomography using a contrast material produces detailed images of both blood vessels and tissues.
CT angiography is used to examine blood vessels in key areas of the body, including the:
Physicians use the procedure to:
- Identify disease and aneurysms in the aorta, both in the chest and abdomen, or in other major blood vessels.
- Detect atherosclerosis disease in the carotid artery of the neck, which may limit blood flow to the brain and cause a stroke.
- Identify a small aneurysm or arteriovenous malformation inside the brain.
- Detect atherosclerotic disease that has narrowed the arteries to the legs and help prepare for endovascular intervention or surgery.
- Indicate disease in the arteries to the kidneys or visualize blood flow to help prepare for a kidney transplant.
- Guide interventional radiologists and surgeons making repairs to diseased blood vessels, such as implanting stents or evaluating a stent after implantation.
- Detect injury to one of more arteries in the neck, chest, abdomen, pelvis or extremities in trauma patients.
- Evaluate arteries feeding a tumor prior to surgery or other procedures such as chemoembolization or selective internal radiation therapy.
- Identify dissection or splitting in the aorta in the chest or abdomen or its major branches.
- Show the extent and severity of atherosclerosis in the coronary arteries and plan for a surgical operation, such as a coronary bypass.
- Sample blood from specific veins in the body to detect any endocrine disease.
- Examine pulmonary arteries in the lungs to detect pulmonary embolism (blood clots from leg veins).
- Angiography may eliminate the need for surgery. If surgery remains necessary, it can be performed more accurately.
- CT angiography is able to detect narrowing of blood vessels in time for corrective therapy to be done.
- CT angiography gives more precise anatomical detail of blood vessels than magnetic resonance imaging (MRI).
- Many patients can undergo CT angiography instead of a conventional catheter angiogram.
- Compared to catheter angiography, which involves placing a catheter (plastic tube) and injecting contrast material into a large artery or vein, CT angiography is a much less invasive and more patient-friendly procedure.
- This procedure is a useful way of screening for arterial disease because it is safer and much less time-consuming than catheter angiography and is a cost-effective procedure. There is also less discomfort because contrast material is injected into an arm vein rather than into a large artery in the groin.
Frequently Asked Questions
What will I experience during and after the procedure?
CT exams are generally painless, fast and easy. With CT, the amount of time that the patient needs to lie still is reduced.
Though the scanning itself causes no pain, there may be some discomfort from having to remain still for several minutes. If you have a hard time staying still, are claustrophobic or have chronic pain, you may find a CT exam to be stressful.
If an intravenous contrast material is used, you will feel a slight pin prick when the needle is inserted into your vein. You may have a warm, flushed sensation during the injection of the contrast materials and a metallic taste in your mouth that lasts for a few minutes. Some patients may experience a sensation like they have to urinate but this subsides quickly.
When you enter the CT scanner, special lights may be used to ensure that you are properly positioned. With modern CT scanners, you will hear only slight buzzing, clicking and whirring sounds as the CT scanner revolves around you during the imaging process.
You will be alone in the exam room during the CT scan. However, the technologist will be able to see, hear and speak with you at all times.
With pediatric patients, a parent may be allowed in the room but will be required to wear a lead apron to prevent radiation exposure.
After a CT exam, you can return to your normal activities. If you received contrast material, you may be given special instructions.
What are the limitations of CT Angiography?
A person who is very large may not fit into the opening of a conventional CT scanner or may be over the weight limit for the moving table.
CT angiography should be avoided in patients with advanced kidney disease or severe diabetes because x-ray contrast material can further harm kidney function.
If a patient’s heart is not functioning normally, or if there are multiple blocked blood vessels, CT angiograms may be hard to interpret. CT angiograms are not yet as reliable as selective catheter injections (performed after puncture of the artery in the groin) in imaging small tortuous arteries, particularly coronary arteries in the rapidly moving heart.