CT Angiography of the Circle of Willis and Carotid Arteries with Intravenous Contrast
A CT scan with IV contrast shows the carotid arteries and circle of Willis to help assess narrowing, blockage, aneurysms, and other vessel abnormalities.
["This test uses CT imaging and intravenous contrast to evaluate the major arteries supplying the brain."]
Key facts at a glance
- LOINC
- 87856-1
- Short code
- CTA Circ of Willis+Carot aa W contr IV
- Synonyms
- CTA Circ of Willis+Carot aa W contr IV
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ct-angio
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What is this test?
CT angiography, or CTA, is an imaging test that creates detailed pictures of blood vessels. In this study, contrast given through a vein helps visualize the carotid arteries in the neck and the circle of Willis at the base of the brain.
Why might I need this test?
Your clinician may order this test to evaluate suspected narrowing or blockage of arteries supplying the brain, especially after symptoms such as a transient ischemic attack or stroke. It may also be used to investigate a suspected aneurysm, abnormal blood flow, or other blood-vessel condition.
How is the test performed?
You lie on a CT scanner table while an IV line is placed and contrast is injected. The scanner takes several rapid images as the contrast moves through your arteries. You may be asked to hold your breath briefly and to remain still to keep the images clear.
How do I prepare for the test?
This test usually requires no special preparation, but follow your appointment instructions about eating, drinking, and medications. Tell the imaging team about any previous contrast reaction, kidney disease, pregnancy or possible pregnancy, and medicines such as metformin, because these factors may affect the instructions or contrast plan.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormal findings may include narrowing, blockage, or an irregular appearance of the arteries supplying the brain. The test may also identify an aneurysm or arterial dissection. Results should be interpreted by a radiologist and reviewed with your clinician in the context of your symptoms and other tests.
Short name
CT angiogram of the head and neck arteries
Frequently asked questions
How is CT angiography different from a routine CT scan?
Can this test determine whether someone has had a stroke?
Are there any risks from the contrast or radiation?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy