Computed Tomographic Angiography (CTA) is an imaging exam that uses a CAT scanner to examine the cardiovascular system or blood vessels in various parts of the body. After intravenous contrast injection in an arm vein, this highly specialized procedure utilizes x-rays to acquire axial images, which are then assembled into three-dimensional views of the blood vessels using state-of-the-art computer software. When used to view the arteries of the heart, this exam is referred to as coronary CTA.
There are two methods of plaque detection with CT scanning of the heart:
Traditionally, catheter-based angiography has been used to evaluate the coronary arteries. In this highly invasive procedure, a long thin tube over a wire is threaded through the groin arteries to the heart where dye or contrast media is injected directly into the arteries and viewed under x-ray.
Although this procedure caries risks, it is still considered to be a very valuable test for those who present with symptoms or acute chest pain.
CTA is a noninvasive procedure. Not only does it visualize the coronary arteries and identify narrowing or blockages, but it also shows the plaque in the artery wall that catheter-based angiography cannot detect. In the invasive procedure the artery may look normal but the CTA may reveal plaque that is actually narrowing it to a significant degree. The calcified plaque can be measured and used to predict the risk of a heart attack. CT angiography can easily detect other dangerous causes of chest pain, such as pulmonary embolism (blood clot to the lungs), or an aneurysm (weakening) or dissection of the aorta, the main blood vessel that leaves the heart.
The 256-slice scanner produces high-quality images much faster and covers twice the area of a 64-slice CT scanner. It is so fast it can capture a three-dimensional image of the entire heart in just two heart beats compared to 10 beats with 64 slice CT. More importantly, the 256 scanner incorporates technology that provides a more accurate and reliable test, and can reduce radiation exposure to the patient by up to 80%.
Coronary CTA directly demonstrates the anatomy of the heart and coronary arteries while nuclear stress testing indirectly diagnoses coronary disease by showing a difference in the distribution of a radioisotope in different parts of the heart muscle. Coronary CTA is more accurate than stress testing, and many experts believe it should be the first test for the evaluation of heart disease. In addition, it has less radiation than nuclear stress testing.
Coronary CTA is covered by Medicare and by many other insurance plans. Check with your particular plan to be sure.
Coronary CTA is a very safe procedure; however, there are some minimal risks involved that are outlined below. If you have any specific questions our qualified professional staff can assist you.
Intravenous contrast reaction: Very rarely, patients may experience an allergic reaction to the intravenous contrast media used for the exam. The allergic reaction can be prevented by taking medication before the test. Patients should inform their doctor of history of allergies to food or medication.
Radiation exposure: There is a minimal risk with x-ray exposure and the amount is well below the level that can cause adverse affects. In addition, areas outside the heart are shielded to decrease the radiation dose. The benefit of the test far outweighs the risk of a heart attack or of radiation exposure. The amount of radiation is usually lower than a nuclear medicine stress test.
Patients with Kidney Disease: There is a risk associated with the intravenous contrast used for the exam in patients with compromised kidney function. Your doctor will order a simple blood test called BUN and Creatinine to establish normal kidney function required for the exam.