What is a cardiac CT scan?
A CT scanner takes many thin X-ray images and reconstructs them into a three-dimensional picture. For the heart there are two main tests. A calcium score measures the amount of calcified plaque in the coronary arteries. A CT coronary angiogram (CTCA) uses an injected contrast dye to show the inside of the arteries in detail. Modern scanners are fast enough to freeze the motion of the beating heart.
What information does it give?
- A calcium score, which places you on a clear scale of cardiovascular risk
- The coronary arteries in detail, showing any narrowing and the type of plaque (CTCA)
- Risk information beyond cholesterol and blood pressure alone
This answers a common question precisely: how much furring is there in the arteries, and does it need treating?
Its role in planning treatment
- Screening people at risk who have no symptoms yet
- Deciding who needs further tests or medication
- Planning interventions such as stents, bypass surgery, TAVI or minimally invasive cardiac surgery
What happens on the day?
- Before — wear metal-free clothing; you may be asked to avoid caffeine and to fast for a few hours if contrast is used
- During — electrodes are placed on the chest, contrast is given through a vein for a CTCA, and you hold your breath for a few seconds while the scanner passes
- After — drink plenty of fluids if you had contrast, return to normal activity, and expect a reported result within 24–48 hours