CT Angiography

Computerized tomographic angiography (CT angiography or CTA) combines the technology of a conventional CT scan with that of traditional angiography to create detailed images of the blood vessels in the body. You may have CTA to assist in the diagnosis of a narrowing or obstruction of the arteries, an aneurysm, deep vein thrombosis, pulmonary embolism or another vascular condition.

Preparing for CTA

Your physician will give you instructions prior to the exam.  Typically, these instructions will include:

  • Avoid foods and liquids for about four hours before the test
  • Continue taking any prescribed medications (confirm this with your physician)
  • Remove all jewelry and other metal objects
  • You may be unsuited for CT angiography if you
  • Have an allergy to contrast dye
  • Have kidney problems
  • Have severe diabetes
  • Are pregnant, because radiation may harm the fetus
  • Have unstable vital signs
  • Weigh more than 300 pounds, because some x ray tables cannot support the weight

The Procedure

Angiography involves the injection of a contrast dye into a large blood vessel to study how the blood flows inside of your body.  During CTA the dye is injected into a vein rather than an artery.   Each imaging facility has its own routine, however, patients may expect the following:

  • You will lie down on a table, which passes through a donut-shaped device. The machine takes X-rays in arcs around the area of your body being examined
  • The technician performing the procedure will talk to you though speakers in the CT scan room
  • 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
  • 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
  • The computer will produce 3-dimensional (3D) images of your blood vessels from the X ray images
  • When the contrast dye is injected into your vein, you may feel warm or flushed
  • Some patients experience mild nausea
  • The entire procedure usually takes 20 minutes to one hour to complete
  • Check with your physician for what to expect after the procedure.  Usually, there are no restrictions 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.

Possible Complications

  • CT angiography sends radiation through your body. Although the amount of radiation for each scan is small, it can accumulate and damage body cells over time with repeated exposures
  • The contrast dye may cause an allergic reaction. Let your physician know if you've had an allergic reaction to this type of dye in advance of the procedure
  • Reactions usually occur immediately and include flushing, itching, or, rarely, difficulty breathing or swallowing
  • Sometimes contrast dye leaks under your skin at the injection site. This can cause redness, swelling, or pain
  • Prior to the test, let your physician know if you are allergic to iodine or shellfish which may place you at increased risk for having an allergic reaction to the contrast dye.  Medications can sometimes be given before the contrast material is administered to lessen the risk of allergic reactions in susceptible patients
  • The contrast material is eliminated by the kidneys and can damage kidney function.  Let your doctor know if you have damaged kidney function
  • Medication and fluids are sometimes given before the contrast material is administered to decrease the effects of the contrast dye on the kidneys
  • Blood tests may be done to evaluate your kidney function before the CT scan

Your physician will give you instructions prior to the exam.  Typically, these instructions will include:

  • Avoid foods and liquids for about four hours before the test
  • Continue taking any prescribed medications (confirm this with your physician)
  • Remove all jewelry and other metal objects

You may be unsuited for CT angiography if you:

  • Have an allergy to contrast dye
  • Have kidney problems
  • Have severe diabetes
  • Are pregnant, because radiation may harm the fetus
  • Have unstable vital signs
  • Weigh more than 300 pounds, because some X ray tables cannot support the weight

Check with your physician for what to expect after the procedure. Usually, there are no restrictions 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.

Android app on Google Play