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CT Angiography, Head Vessels — Without Contrast

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

A CT scan creates detailed images of blood vessels in the head. The noncontrast series may be used with contrast-enhanced images to evaluate the brain and its vessels.

Quick summary

["This imaging test helps doctors evaluate the brain and blood vessels in the head for conditions such as bleeding, blockage, or aneurysm."]

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

Key facts at a glance

LOINC
42293-1
Short code
CTA Head ves WO contr
Synonyms
CTA Head ves WO contr
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 a radiology test that uses computed tomography to create detailed pictures of the blood vessels in the head. Although the order identifies a noncontrast component, a complete angiogram may also include images taken after intravenous contrast is given.

Why might I need this test?

A head CTA may be ordered to investigate symptoms such as sudden severe headache, weakness, speech difficulty, vision changes, or seizures. It can help identify bleeding, narrowed or blocked vessels, aneurysms, and certain abnormalities involving the brain or its blood supply.

How is the test performed?

You lie on a CT scanner table while an X-ray machine rotates around your head. The scan is quick and generally painless, and a radiologist reviews the images for abnormalities.

How do I prepare for the test?

Follow the instructions provided by the imaging center. If intravenous contrast will be used, tell the staff about any kidney disease, previous contrast reactions, or allergies; they will also ask about pregnancy and other relevant medical conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Head CT angiogram without contrast

Frequently asked questions

Is this a blood test?
No. This is an imaging test performed with a CT scanner, not a blood or urine laboratory test.
Does the test use contrast?
The name refers to imaging without contrast, but the full examination may also include contrast-enhanced images. The imaging center will explain what is planned before the scan.
Is CT angiography painful?
The scan itself is generally painless. If intravenous contrast is used, the injection may cause a brief warm or flushing sensation, and some people may be nauseated.
  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