CT Angiography of the Head — Intravenous Contrast
A CT scan that uses intravenous contrast to show the arteries of the brain and help evaluate narrowing, blockage, or bulging vessels.
["This scan creates detailed images of the brain's arteries and may be used to investigate symptoms such as sudden weakness, speech difficulty, severe headache, or vision changes."]
Key facts at a glance
- LOINC
- 36814-2
- Short code
- CTA Head Arteries W contr IV
- Synonyms
- CTA Head Arteries 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 uses multiple X-ray images and injected contrast to create detailed pictures of the arteries supplying the brain.
Why might I need this test?
Your clinician may order this test to evaluate a suspected aneurysm, blood clot, arterial narrowing, or other circulation problem. It may also be used to assess certain symptoms that could involve the brain, including sudden weakness, trouble speaking, severe headache, or vision changes.
How is the test performed?
You lie on a table that moves through a CT scanner. Intravenous contrast is given through a vein in your arm, and the scanner quickly takes many X-ray images to examine the brain and its arteries.
How do I prepare for the test?
Fasting is usually not required, but follow your clinician's instructions. Tell the imaging team about kidney disease, prior contrast reactions, iodine or shellfish allergies, and any possibility of pregnancy before the scan.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormal findings may indicate a narrowed or blocked brain artery, an aneurysm, an abnormal blood vessel, or signs of an injury or stroke. Results are interpreted together with your symptoms, medical history, and other imaging or laboratory tests. The scan also provides information about the brain tissue, although its main purpose is to evaluate the arteries.
Short name
Head CT angiography
Frequently asked questions
Is CT angiography the same as a routine head CT?
Does the test use radiation or contrast?
How soon will I receive the results?
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