What is the difference between a Coronary Artery Calcium (CAC) scoring test and a Coronary Computed Tomography (CT) scan?

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Last updated: April 14, 2025View editorial policy

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From the Guidelines

A calcium scoring test and a coronary calcium CT scan are essentially the same procedure, utilizing computed tomography (CT) technology to detect and measure calcium deposits in the coronary arteries, with the most recent evidence from 1 supporting its use in risk assessment for future cardiac events. The test produces a "calcium score" that helps physicians assess a patient's risk of coronary artery disease and potential future cardiac events.

  • The procedure takes about 10-15 minutes, during which the patient lies on a table that moves through a donut-shaped CT scanner while electrodes monitor their heart rhythm.
  • No contrast dye is used, and the radiation exposure is relatively low compared to other cardiac imaging tests, with a typical effective dose of 0.9 to 1.1 mSv, as stated in 1.
  • The calcium score ranges from zero (no detectable calcium) to over 400 (extensive calcification indicating significant coronary artery disease). This test is typically recommended for people with intermediate risk factors for heart disease, such as family history, high cholesterol, or high blood pressure, particularly those between ages 40-70 without known heart disease, as suggested by 1.
  • The presence of calcium indicates atherosclerosis (plaque buildup), as calcium is part of the healing process when arteries are damaged.
  • According to 1, the simple quantification of coronary artery calcification (CAC) is reasonably predictive of adverse hard events, and the advantage of coronary CT angiography (CTA) testing over CAC alone is not likely to be easily demonstrable for hard events.

From the Research

Difference between Calcium Scoring Test and Calcium Coronary CAT Scan

  • A calcium scoring test is a non-invasive test that uses computed tomography (CT) to detect and measure the amount of calcium in the coronary arteries, which is a marker of atherosclerosis 2, 3.
  • A calcium coronary CAT (CT angiography) scan, on the other hand, is a more detailed test that uses CT to visualize the coronary arteries and detect any blockages or stenoses 4, 5.
  • The main difference between the two tests is that a calcium scoring test only measures the amount of calcium in the coronary arteries, while a calcium coronary CAT scan provides a more detailed image of the coronary arteries and can detect blockages or stenoses 5, 6.
  • Both tests can be used to assess cardiovascular risk, but the calcium coronary CAT scan is more accurate in detecting stenoses and blockages 5, 6.
  • The calcium scoring test is often used as a screening test to identify individuals at high risk of cardiovascular disease, while the calcium coronary CAT scan is used to diagnose and monitor coronary artery disease 2, 3.

Key Similarities and Differences

  • Both tests use CT technology to visualize the coronary arteries 2, 4.
  • Both tests can detect calcium in the coronary arteries, which is a marker of atherosclerosis 2, 3.
  • The calcium scoring test is less expensive and less time-consuming than the calcium coronary CAT scan 3.
  • The calcium coronary CAT scan provides more detailed information about the coronary arteries and can detect blockages or stenoses, while the calcium scoring test only measures the amount of calcium 5, 6.

Clinical Applications

  • Calcium scoring tests are often used to assess cardiovascular risk in asymptomatic individuals 3.
  • Calcium coronary CAT scans are used to diagnose and monitor coronary artery disease, and to guide treatment decisions 5, 6.
  • Both tests can be used to monitor the progression of coronary artery disease and to assess the effectiveness of treatment 2, 3.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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