Patient information

Computed tomography angiogram (CTA) and magnetic resonance angiogram (MRA)

What are CRA and MRA?

Computed Tomography Angiogram (CTA) and Magnetic Resonance Angiogram (MRA) are non-invasive tests that use images to give detailed information about the body’s blood vessels. These tests provide 3-D images that allow your doctor to see your blood vessels from a variety of angles. Your doctor will use this information to judge your condition and determine the best treatment for you.


Before a CTA scan, a nurse or technician may place a thin, flexible tube, known as an intravenous (IV) catheter, into your arm. A dye is injected into your blood vessels through the catheter, which makes the blood vessels more visible on the scan, and makes it easier to diagnose some diseases of the blood vessels. A CTA uses an x-ray to get the images of your blood vessels.

An MRA is performed like a CTA but can be done without using a dye in your blood vessels. In this case, your doctor will determine whether or not a dye will be needed to assess your condition. An MRA uses a strong magnet to take pictures of your blood vessels.

Before testing, you may be asked whether you have any allergies. Other questions may include:

  •     Do you have any kidney disease?
  •     Do you have a pacemaker?
  •     Are you pregnant?
  •     Do you have any stimulators, pumps, or other metallic implants in your body?

You may also be asked to have a blood test before the imaging exam, to make sure your kidneys are working normally, which is vital because the kidneys process the dyes used in imaging tests.