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CT Angiography of Head Blood Vessels With or Without Intravenous Contrast

Published: August 9, 2026Updated: August 16, 2026

A CT scan that uses X-rays and sometimes intravenous contrast to examine blood vessels in the head and nearby areas.

Quick summary

["This imaging test helps identify narrowing, blockage, aneurysms, and other abnormalities of blood vessels supplying the head."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
30593-8
Short code
CTA Head ves WO+W contr IV
Synonyms
CTA Head ves WO+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?

Head CT angiography, or CTA, is an X-ray–based imaging test that shows the blood vessels in and around the head. The examination may include images taken before and after intravenous contrast is given.

Why might I need this test?

It may be ordered to evaluate symptoms such as sudden weakness, speech difficulty, severe headache, dizziness, or vision changes. It can also be used to investigate suspected aneurysms, vessel narrowing, or abnormal blood flow.

How is the test performed?

You lie on a CT table while the scanner takes X-ray images. If contrast is used, it is given through a vein in your arm, and the scan is repeated after it moves through your blood vessels. The procedure uses radiation and usually takes less time than a conventional CT scan.

How do I prepare for the test?

Follow the imaging center's instructions about eating, drinking, and medications. Tell the care team if you have kidney disease, a prior contrast reaction, allergies, or might be pregnant, because these factors may affect the choice of contrast and other preparation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Head CT angiography

Frequently asked questions

Is this the same as a routine head CT?
No. A routine head CT primarily shows the brain and skull, while head CT angiography is designed to show the blood vessels more clearly.
Why might I need IV contrast?
Contrast can improve the visibility of blood vessels and help the radiologist identify narrowing, aneurysms, and other vascular abnormalities. The imaging center will confirm whether contrast will be used.
Is head CT angiography safe?
It is generally well tolerated. It uses ionizing radiation, and IV contrast can occasionally cause an allergic reaction or kidney-related problem, so tell the care team about relevant allergies, kidney disease, or previous contrast reactions.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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