Angiography or arteriography is a time-tested way to study the health of veins and arteries. Though often associated with the heart, it can be used to determine whether blood vessels throughout the body are blocked, damaged or malformed.
Before, During and After the Procedure (Cardiac/Heart)
Before, During and After the Procedure (Brain/Neck)
Before, During and After the Procedure (Abdomen, Kidneys, Legs)
A computed tomography angiogram (CT angiogram) is a test that usesX-rays to provide detailed pictures of the heart and the blood vessels that go to the heart, lung, brain, kidneys, head, neck, legs, and arms.
A CT angiogram can show whether a blood vessel is blocked, where the blockage is, and how big the blockage is. The test can also show whether there is a bulge (aneurysm) or a buildup of fatty material called plaque in a blood vessel.
During a CT angiogram, you lie on a table that passes through a doughnut-shaped opening in the scanner. A special dye (contrast material) is put in a vein (IV) in your arm or hand to make the blood vessels easier to see on the scan. If you are having a CT angiogram to look at your heart and the blood vessels that go to it (coronary arteries), you may be given a medicine called a beta-blocker to slow your heart rate during the test.
With computed tomography angiography (CTA), no tube is necessary and the dye can be placed with a simple injection in the arm. CTA uses a Computed tomography (CT) scanner (sometimes called a CAT scan) to create images of blood vessels. Because there is no need to thread a catheter through the body, a CTA is usually faster and causes less discomfort than traditional angiography. A CT scanner uses a thin X-ray beam and advanced computer analysis to create highly detailed images.
In a CT scan, x rays and computers create images that show cross-sections, or slices, of your body. Angiography involves the injection of contrast dye into a large blood vessel, usually in your leg, to help visualize the blood vessels and the blood flow within them. When the contrast dye is used to visualize your veins, the study is called a venogram, and when it is used to visualize your arteries, it is known as an arteriogram. CT angiography is similar to a CT scan, but the contrast dye is injected into one of your veins shortly before the x ray image is performed. Because the dye is injected into a vein rather than into an artery, as in traditional angiography, CT angiography could be considered less invasive.
Your physician may order CT angiography to help diagnose a narrowing or obstruction of the arteries, an aneurysm, deep vein thrombosis, pulmonary embolism, or another vascular condition.
During the study, you will lie down on a table, which passes through a donut-shaped device. Inside the device, a machine takes x rays in arcs around the area of your body being examined. Tissues of varying densities absorb these x rays in varying amounts. The computer assigns these densities different numerical values and then plots an image based on these values, in shades of gray. During the CT angiogram, a dose of contrast dye will be injected into one of your veins. As the dye flows through your circulatory system, it will highlight your blood vessels on the scan. A computer will produce 3-dimensional (3D) images of your blood vessels from the x ray images.
While traditional angiography must be used for various treatment options (such as the placement of stents or angioplasty), angiography to diagnose conditions is increasingly being done using noninvasive CT angiography.
CT ANGIOGRAMS ARE PERFORMED FOR THE FOLLOWING REASONS:
- To detect aneurysms (places where a blood vessel bulges or balloons out)
- To determine whether any blood vessels are torn
- To examine the buildup of plaque or other blockages in blood vessels
- To determine the degree of artery disease, particularly of the blood vessels around the heart
- To investigate problems in the brain, such as stroke or cerebral bleeding
- To identify blood-flow problems, such as circulatory problems in the legs
- To examine any malformations of the blood vessels
- To evaluate coronary veins before placement of a pacemaker
- To check on the effectiveness of an earlier angioplasty or stent procedure
- To evaluate the results of a bypass surgery
- Angiograms are also sometimes used by surgeons to plan an operation or to choose the best surgical procedure
WHAT HAPPENS DURING A CT ANGIOGRAPHY?
Before the x rays are taken, the contrast material will be injected into a vein in your arm or hand using an automatic injector machine, which controls the timing and rate of injection. The machine may continue to inject contrast dye into your vein throughout the test. The contrast material may make you feel flushed and warm, and it sometimes can produce a mildly sick-to-your-stomach sensation.
You will need to lie very still on the scan table that slides into the gantry, which is the donut-shaped device that houses the scanning equipment, in order to get the best quality images. The machine is quiet and relatively open; only the part of the body being examined lies inside the gantry. As a medical technician operates the scanning machine in another room, he or she watches and speaks to you through speakers in the CT scan room.
An x ray tube slides around the gantry, passing narrow beams of low-dosage x-rays in an arc over the body. These beams reflect onto a detector positioned opposite the x-ray source. After the x ray source completes an arc, the scanning table moves forward a small distance and the x ray source transmits another arc of x rays. Most CT angiographies use a type of machine called a spiral CT machine, which is able to record a large number of pictures–as many as 1,000 pictures in each arc — in a short time. The detector transmits the x ray energy to a computer, which transforms the information about the reflected energy into a 3D image. To create images from different angles, the technician may adjust the position of the scanning table.
You must remain very still as the CT scanning machine operates. The technician may ask you to hold your breath for 10 to 25 seconds at a time, because even the motion of breathing can blur the images.
The entire procedure usually takes 20 minutes to 1 hour to complete.
WHAT CAN I EXPECT AFTER A CT ANGIOGRAPHY?
There are no restrictions after a CT angiography and you can resume normal activities immediately.
You should drink plenty of fluids following the test to speed excretion of the contrast agent and to guard against dehydration.
ARE THERE ANY COMPLICATIONS?
The most serious early complication of CT angiography is an allergic reaction to the contrast dye. Reactions usually occur immediately and include flushing, itching, or, rarely, difficulty breathing or swallowing. Notify your physician if you experience any of these symptoms. Sometimes contrast dye leaks under your skin at the injection site. This can cause redness, swelling, or pain. The contrast dye can also damage kidney function depending upon the amount of the dye used and whether you have any kidney problems that already exist.