How is the CT Angiogram Procedure Performed?
A patient is asked to drink only water before the CT angiogram procedure. Upon arrival at the CT scanner, the patient will be asked to remove any metal objects from their body. The patient will be asked if they have any allergies, which may be important as one of the risks of CT angiography heart scans is an allergic reaction to contrast material. A physician or assistant will then place an IV into a peripheral vein, usually in the patients forearm. The patient is then brought to the CT scanner. Before the exam, a dose of contrast agent is administered into the IV. This ensures that the arteries will stand out when the physician reads the scan.
The patient will then lay down on the CT table, and the scan will begin. During the CT scan, the scanner will rotate around the patient and take a large number of x-ray images. These x-ray images are then sent to a computer. Because the x-ray images are taken from a variety of angles, the computer is able to put them together and create a 3-dimensional image of the patient. Unlike a traditional x-ray, which is taken in only 2-dimensions, this allows the physician to look at the arteries and other organs in the body from essentially any direction, which is extremely valuable in diagnosing disease.
Today's CT scanners use multiple detectors to capture images from each rotation of the CT scanner. The top machines use up to 64 detectors, and are also known as "64-slice" scanners. For the patient, this means that the scan time is very short, and may be completed in as little as 10 seconds. For the physician, this provides a high level of detail that was previously unavailable. During a heart scan, this is very important because the arteries of the heart are small and the heart continues to move during the exam. Therefore, the best coronary angiograms are completed using multidetector scanners.