Contrast-Enhanced CT Heart Scan
Coronary artery disease can occur without calcium deposits, as well. This is more common in people under the age of 60 who have risk factors such as:
In these cases, doctors look for non-calcified plaque (also called “soft” plaque). Soft plaque can be detected with contrast-enhanced CT images of the coronary artery walls. Images taken with a contrast agent in the bloodstream can reveal irregularities in the artery walls and stenoses (narrow areas). These irregularities may indicate the existence of soft plaques.
Prior to the actual CT heart scan, patients will require an injection of a contrast material, such as barium, to increase visibility. This contrast material has a different opacity than the soft tissues of the body, and will make the soft tissues and irregularities “stand out” on the CT images. Contrast material is injected into the patient through a small needle attached to an intravenous line. This intravaneous line is inserted into a vein in the hand or arm. In some cases, the contrast material may be given by mouth or through an enema. Sometimes, all three methods of contrast material are used.
In a contrast-enhanced CT heart scan, several x-ray beams pass through the heart at various angles. Special sensors measure the amount of radiation absorbed by different tissues within the heart. A CT heart scan will take place in either a hospital or in an outpatient radiology center.
During a CT heart scan, the patient lies still on a table. The table is rolled into the center of the CT scanner. The CT scanner revolves around the patient and emits and records x-ray beams. The different areas of the heart absorb different amounts of x-ray. As the x-ray beams rotate around the patient, x-ray detectors rotate opposite from the beams and measure the amount of radiation absorbed. A special computer program then forms graphical cross-sections, or “tomograms,” based on these x-ray absorption differences.
Once the patient enters the scanner, the technologist may turn on special lights to ensure the patient is positioned properly for the CT heart scan. Pillows, “head holders” and other devices may be required to ensure the patient remains properly positioned throughout the exam. Though the technologist will not actually be in the room with the patient, an intercom within the scanner allows the patient and technologist to communicate throughout the procedure.
[SSI4] The duration of the CT heart scan depends on the number of images needed to get the information the doctor requires. At the conclusion of the CT heart scan, the technologist will look over the images to ensure sufficient images have been created to provide the radiologist with the necessary information. If more images are necessary, the technologist will ask the patient to stay for further scanning.