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CT Angiography, Blood Vessels Without Contrast

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

A CT scan that creates detailed images of blood vessels without using iodinated contrast dye. It may help evaluate vessels for narrowing, blockage, aneurysms, or other abnormalities.

Quick summary

["This scan images the body's blood vessels without iodinated contrast dye."]

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

Key facts at a glance

LOINC
36424-0
Short code
CT Abd WO contr
Synonyms
CT Abd 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
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, uses X-ray computed tomography to produce detailed pictures of blood vessels. In this version, no iodinated contrast dye is injected, so images are obtained without contrast enhancement.

Why might I need this test?

Your clinician may order CTA to evaluate blood vessels when there is concern about narrowing, blockage, aneurysm, dissection, or blood clots. The reason for the test and the area being examined depend on your symptoms and medical history.

How is the test performed?

You lie on a table that moves through a CT scanner while X-ray images are taken. The scan usually takes only a few minutes, although more images or special breathing instructions may be needed. A technologist or radiology team will explain the procedure and may place an IV line if it is part of the examination.

How do I prepare for the test?

Follow the instructions provided by the imaging center. You may need to avoid eating or drinking for a specified period, and you should tell the staff about pregnancy, allergies, kidney disease, implanted devices, and recent imaging tests. Because this version does not use iodinated contrast, contrast-related restrictions generally do not apply unless your clinician orders a different protocol.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CT angiography without contrast

Frequently asked questions

Does this test use contrast dye?
No. The name indicates that iodinated contrast dye is not used. Some CTA examinations do use contrast, so confirm the planned protocol with your clinician or imaging center.
Is CT angiography the same as a standard CT scan?
Both use X-ray computed tomography, but CTA is designed to focus on blood vessels and often includes specialized image processing. A standard CT scan may cover a broader area of the body.
Will I need to stay in the hospital?
Usually not. CT angiography is generally an outpatient procedure, and most patients return home afterward. Follow your facility's instructions because sedation or observation is uncommon but may be needed in certain circumstances.
  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