Patient education: Computed tomographic angiography (The Basics)

What is computed tomographic angiography? — Computed tomographic angiography, or "CT angiography," is a procedure doctors do to look at blood vessels in the body. There are 2 main types of blood vessels: arteries and veins. These carry blood around the body.

There are 2 parts to CT angiography:

●First, a special dye called "contrast" is injected into 1 of your veins. This is done through a thin tube called an "IV." In some cases, you might get the procedure without any contrast, but the images of the vessels will not be as clear.

●Then, the doctor uses a type of imaging called "computed tomography" on part of your body. The dye shows up on the images and shows how blood moves through your body.

CT angiography can show if there are problems with any of your blood vessels. For example, it can show if a vessel is blocked, damaged, enlarged, inflamed, or abnormal in other ways.

Your doctor might want you to have CT angiography:

●To check the blood vessels in your heart, kidneys, brain, lungs, intestines, limbs, or another part of the body

●Because you have symptoms of cardiovascular disease – "Cardio" means having to do with the heart. "Vascular" means having to do with the blood vessels.

●To check for a blood clot or other blockage in a vessel

●To measure the size of blood vessels or other structures

●To find the source of bleeding inside your body

●To look at the soft tissues around the vessels to see if they are causing a blockage

●To help plan treatment

How do I prepare for CT angiography? — The doctor or nurse will tell you if you need to do anything special to prepare.

Before your procedure, your doctor will do an exam. They might send you to get tests, such as lab tests. These include tests to check your kidney function.

Your doctor will also ask you about your "health history." This involves asking you questions about any health problems you have or had in the past, past surgeries, and any medicines you take. Tell them about:

●Any medicines you are taking – This includes any prescription or "over-the-counter" medicines you use, plus any herbal supplements you take. It helps to write down and bring a list of any medicines you take, or bring a bag with all of your medicines with you.

●Any allergies you have

●Any bleeding problems you have – Certain medicines, including some herbs and supplements, can increase the risk of bleeding. Some health conditions also increase this risk.

●Any problems with your kidneys

●If you have trouble breathing when lying flat

●If you get nervous in small spaces – Some machines are closed in. If small spaces make you feel nervous or anxious, tell your doctor. They can talk to you about what your machine will be like. They might be able to give you a type of medicine called a "sedative" to help you relax during the procedure.

You will also get information about:

●Drinking fluids before your procedure – It's important to make sure that you are drinking enough.

●Avoiding things that raise your heart rate – If your heart is being scanned, you might need to avoid caffeine, exercise, and smoking for some time before your procedure.

●Taking your medicines – Depending on what part of your body is being looked at, your doctor might ask you not to take certain medicines before your procedure. If so, they will tell you when to stop taking them.

●What help you will need after your procedure – In some cases, you will need to have someone else bring you home.

Ask the doctor or nurse if you have questions or if there is anything you do not understand.

What happens during CT angiography? — When it is time for the procedure:

●You will change into a hospital gown and remove any metal objects from your body. It's important to remove any jewelry in the area of the body being scanned.

●You will get an "IV," which is a thin tube that goes into a vein. This can be used to give you fluids and medicines.

●If your heart or chest is being scanned, you will also have small, sticky patches called "ECG leads" placed on your chest. These measure your heartbeat.

●The person doing the procedure (called a "technologist") will use your IV to inject the contrast dye into your body, if you are getting it. You might have a warm or tingling feeling throughout your body or notice changes to your taste or smell. Sometimes, you might get 1 scan without contrast, and then another scan with contrast.

●You might get other medicines through your IV or by mouth before or during your CT scan.

●You will lie on the narrow table of the CT machine. The table slides into the scanner, which looks like a large tube or donut (figure 1).

●There will be a speaker so you can talk to the technologist from inside the scanner. The technologist will be in another room.

●You need to lie very still during the CT scan so that the images are clear. You might also be asked to do other things, like hold your breath for a few seconds or change position. This depends on which part of your body is being scanned.

●The technologist will start scanning.

●The table might slide in and out of the scanner a few different times. This is so the technologist can get different types of pictures.

●Once the procedure is over, the table will slide back out of the scanner, and your IV will be removed.

What happens after CT angiography? — This depends on whether you were given medicines to help you relax. It also depends on whether you are at risk for kidney problems with contrast dye.

●If you don't have kidney problems and didn't get any medicines to help you relax, you can usually go home right away.

●If you had medicines to help you relax, you will be moved to a "recovery room" after your procedure. These medicines can make you sleepy. The staff will watch you closely as your medicine wears off. You might need someone else to bring you home after your procedure.

●If you have kidney problems and you got contrast dye, you will get extra fluids through your IV before you go home. This is because people with kidney problems need more fluids to flush the dye from their bodies.

●If you were given contrast dye, drink plenty of fluids for a few days. This helps clear the dye from your system.

What are the risks of CT angiography? — Your doctor will talk to you about all of the possible risks and answer your questions. Possible risks include:

●Minor or serious allergic reaction to the dye

●Kidney damage from the dye

●Radiation exposure – Your doctor can talk to you about how much radiation you will be exposed to.

What else should I know? — You might get your results the same day, or it might take a little longer for them to be read by an expert. Your doctor or nurse will let you know when to expect your results.

If your CT angiography shows any abnormal results, your doctor or nurse will talk to you about what to do next.

More on this topic

Patient education: Angiography (The Basics)
Patient education: Magnetic resonance angiography (The Basics)
Patient education: CT scan (The Basics)
Patient education: Coronary artery disease (The Basics)
Patient education: Carotid artery disease (The Basics)