CT Angiography

Blood circulates in the human body through blood vessels. The deposition of calcium or plaques in these vessels can cause narrowing and blockages. These can be identified by the procedure called CT angiography. This is a diagnostic tool that involves the injection of a contrast dye into a blood vessel which helps to visualise the blood flow within them.

Computerised tomographic angiography or CT angiography is a test that combines the technology of a CT scan (X-ray imaging that take images of the body in the form of slices) and angiography to create images of the blood vessels.

Indications and contraindications

CT angiography is indicated to diagnose narrowing, obstruction or bulging of blood vessels .

However, CT angiography is not recommended if you are allergic to iodine or shellfish. Kindly inform your physician regarding the same as it can increase the risk of allergies due to the contrast dyes. Medications can be prescribed to reduce the risk of these allergies. You may also be unsuited for a CT angiography test if you are pregnant as the rays may harm the foetus or if you have sever kidney disease as the dye can further damage the already sub-optimal function of the kidney.

Preparing for the procedure

Your physician might ask you to avoid foods and liquids up to 4 hours prior to the procedure. You may be allowed to continue medications that you are taking, but it is always advisable to confirm with your doctor prior to the examination.


During CT angiography, a contrast dye is injected into your vein (mostly in the arm) with an injector machine which monitors the time and rate of the injection. This might make you feel warm or sick in your stomach.

You will be made to lie still on the scanning table in order to get good quality images. The scanning equipment consists of an X-ray tube which passes narrow beams of X-ray in the form of an arc over the body. The X-ray beams reflect on a detector present just opposite to the X-ray source. This machine can take about 1,000 pictures in a very short span of time and transmit them to a computer which converts it into 3D images. The position of the scanning table can be adjusted if images from different angles need to be taken. During the procedure, you may be asked to hold your breath for about 10 to 25 seconds as breathing may blur the image. The entire procedure may take about 20 minutes to 1 hour to complete.

Post-procedure care

After CT angiography, you will be advised to drink lots of fluids to flush out the contrast dye and avoid dehydration. There are no major restrictions and you will be able to resume your normal activities soon after the procedure.


CT angiography may cause allergic reactions such as itching, difficulty in swallowing or breathing, or flushing due to the contrast dye. These reactions should be reported to your doctor immediately. The contrast dye may also leak under the skin at the site of injection causing pain, swelling or redness. If you have any existing kidney problems, the contrast dye may cause further damage to the kidney function depending on the amount of dye used. Since CT angiography is an X-ray test, the radiation emitted might damage the body cells with repeated exposure.

However, under a skilled specialist, CT angiography can be a safe and successful minimally invasive procedure to diagnose diseases involving the arteries and veins.