A computed tomography (CT) scan is a medical imaging procedure that uses X-rays and computer processing to create detailed cross-sectional images of the body. Unlike a traditional X-ray, a CT scan provides a three-dimensional view of soft tissues, blood vessels, and bone. Specialized cardiac CT scans are non-invasive tools for diagnosing a range of heart conditions, from blockages in the arteries to structural defects.
Visualizing Arteries with CT Angiography
Coronary CT Angiography (CCTA) creates highly detailed images of the coronary arteries, which supply blood to the heart muscle. This technique is often used when a patient has acute symptoms, such as chest pain, to quickly diagnose or rule out arterial problems. CCTA is a non-invasive alternative to traditional catheter-based angiography.
The procedure involves injecting an iodine-based contrast dye into a vein. The dye travels through the bloodstream and highlights the coronary arteries on the scan. The goal of CCTA is to detect narrowing, or stenosis, caused by plaque buildup within the arteries.
CCTA identifies both calcified (hard) plaque and non-calcified (soft) plaque. Soft plaque is often lipid-rich and vulnerable to rupture, which can trigger a heart attack. Detecting this plaque helps guide patient treatment, even before severe narrowing occurs. A clear CCTA scan can effectively exclude significant coronary artery disease in symptomatic patients.
Measuring Heart Disease Risk with Calcium Scoring
A Coronary Artery Calcium (CAC) Scoring scan is a non-contrast CT procedure used to assess future heart disease risk in individuals without symptoms. This scan measures the amount of calcified plaque in the coronary arteries. Calcium deposits mark atherosclerosis, which is the hardening and narrowing of the arteries that develops over time.
Results are quantified using the Agatston score, a numerical value calculated from the total area and density of the detected calcium deposits. A score of zero suggests a minimal chance of a heart attack, indicating no detectable calcified plaque. Conversely, a score greater than 400 signifies extensive disease and a high risk of a future cardiac event.
The CAC score helps patients whose heart disease risk is uncertain based on traditional factors like cholesterol or blood pressure. For instance, a score between 100 and 300 indicates moderate plaque deposits. This predictive information helps doctors determine if a patient would benefit from preventative treatments, such as statin therapy.
Identifying Non-Artery Structural Problems
Beyond the coronary arteries, CT scans provide a comprehensive view of the entire chest cavity, allowing for the detection of many structural heart and vascular issues. The technology can visualize the chambers of the heart, the valves, and the surrounding structures. This is useful when other imaging methods, like echocardiography, are inconclusive, or when a patient cannot undergo an MRI.
CT scans are used for evaluating the large blood vessels connected to the heart, particularly the aorta. They can detect conditions like an aortic aneurysm, a bulging of the vessel wall, or an aortic dissection, a tear in the inner layer of the aorta. This visualization is important for planning surgical interventions.
The scan provides detailed information about the pericardium, the sac surrounding the heart. Doctors can detect pericardial disease, such as inflammation or fluid accumulation, which can impair its function. CT imaging is also useful for identifying cardiac tumors or masses. It can also assist in the evaluation of congenital heart defects, which are structural abnormalities present from birth.