CT Coronary Angiogram and Calcium Score

CT Coronary Angiogram and Calcium Score

Computer Tomography (often referred to as CT) is a high-resolution X-ray scan employing advanced computer processing to create detailed images of internal organs.

CT coronary angiogram involves the use of CT to image the heart arteries to detect pathology such as calcium and cholesterol deposits also known as plaques. The amount of calcium detected is expressed as a Calcium Score. This score is age-adjusted and used as part of the risk assessment of coronary artery disease. The CT scan will further quantify the degree of narrowing of the heart arteries by these plaques.

CT Angiogram involves intravenous injection of X-ray dye to show up the arteries under X-ray. The dye is usually harmless (see FAQ) and the X-ray dosed in modern machines is kept to an absolute minimum.

The test takes about 1 to 2 hours, including the preparation and the full report is usually available the following day.  

CT Coronary Angiogram and Calcium Score
CT Coronary Angiogram and Calcium Score


  1. Is the X-ray dye (contrast) completely safe?
    • X-ray contrast is overall very safe. The 2 main concern when it comes to contrast safety is allergy and kidney disease. Subjects who have previous history of severe allergy, brittle asthma and seafood allergy should inform the cardiologist and radiologist who is supervising the test. Preventive antihistamine is often given to negate such side effects.
      Since the X-ray dye is cleared from our body through the kidneys, patients with very poor kidney function may suffer from contrast induced kidney trouble. This is especially true in people with diabetes. Certain drugs like metformin should also be withheld for 24 hours prior to CT Angiogram.
  1. My CT scan came back showing a 25 to 50% blockage of my heart artery. I felt absolutely fine but now I am really worried. What should I do?
    • Just like we have the odd age spot and wrinkle when we cumulate the mileage, some degree of narrowing of our blood vessels is almost inevitable later on in life. Mild degree of vessel narrowing serve as warning sign for us to be more careful with our lifestyle. Regular exercise, healthy diet and a preventative medication to lower our cholesterol is often all that is needed.
  2. What is the difference between a coronary angiogram and a CT coronary angiogram?
    • The former is a more invasive procedure involving putting a soft catheter inside our body to inject contrast directly into the heart vessels. CT angiogram is non-invasive and therefore a safer procedure.
    • Angiogram is more precise in the quantification of artery narrowing compared to CT. CT angiogram also have very limited role in subjects with heavy calcium deposits.
    • If the CT angiogram is very abnormal, the patient is often referred for an angiogram as a prelude to more detailed therapy.