Coronary Calcium Score (CAC)
A coronary calcium score, also called a CAC score or Agatston score, is a non-contrast CT scanthat detects and quantifies calcium deposits in the coronary arteries. The result is a number — 0 means no calcium detected (lowest measured risk); higher scores indicate more calcified plaque burden.
CAC scoring is generally considered for asymptomatic adults aged 40–75 at intermediate cardiovascular risk (10-year ASCVD risk 7.5–20%) where the result would influence treatment decisions. It is one of the lower-radiation CT studies and does not require IV contrast.
Key limitation: CAC only detects calcified plaque. Non-calcified (soft) plaque — which can also be clinically significant — is not detected by calcium scoring.
Coronary CT Angiography (CCTA)
Coronary CT angiography (CCTA) is a contrast-enhanced CT scan that uses iodinated IV contrast to visualize the coronary arteries in detail. Unlike a calcium score, CCTA shows both calcified and non-calcified plaque, coronary anatomy, and potential blockages or stenosis.
CCTA may be appropriate for patients with intermediate cardiovascular risk, atypical chest pain, family history of premature coronary disease, elevated cholesterol or Lp(a), or equivocal stress test results. Because it uses IV contrast, kidney function (eGFR), contrast allergy, and medication review are important safety considerations.
Key Differences at a Glance
| Feature | CAC Score | CCTA |
|---|---|---|
| Contrast | No IV contrast | IV contrast required |
| What it shows | Calcified plaque only | Calcified + non-calcified plaque, anatomy |
| Radiation | Low dose | Higher than CAC |
| Typical use | Risk stratification in asymptomatic patients | Detailed coronary evaluation |
| Preparation | Minimal | eGFR, allergy screening, heart rate control |
| Cost (self-pay) | Often $50–$150 | Often $200–$800 |
| Detects soft plaque | No | Yes |
Which Study Is Right for You?
The choice between CAC scoring and CCTA depends on your individual cardiovascular risk profile, age, symptoms, and what clinical question needs to be answered. A licensed provider must review your history to determine which study — if any — is medically appropriate.
CAC scoring is often a first-line screening tool for asymptomatic intermediate-risk patients. CCTA provides more detailed anatomical information and may be appropriate when more information is needed beyond what a calcium score can tell you.
Important: If you have chest pain, shortness of breath, fainting, or symptoms concerning for a heart attack or emergency, call 911 or go to the emergency room. These studies are for non-emergency, preventive, or risk-stratification purposes only.
Need a Provider Order for Either Study?
Most imaging facilities require a provider order for both CAC scoring and CCTA. DOD provides $40 virtual provider reviews for cardiac imaging order requests when medically appropriate.