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Functional MRI (fMRI) of the Brain Without Contrast

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

An MRI-based brain imaging test that measures blood flow and activity in brain regions, usually without injecting contrast dye.

Quick summary

["This test helps show which brain areas are active and can assist with planning for brain surgery or treatment."]

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

Key facts at a glance

LOINC
105166-3
Short code
fMR Brain WO contr
Synonyms
fMR Brain 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
mr-functional
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?

Functional magnetic resonance imaging, or fMRI, is an MRI technique that detects changes in blood flow and oxygen use to identify active areas of the brain. It is used to map brain functions such as movement, language, and memory.

Why might I need this test?

A clinician may order fMRI when a tumor, stroke, epilepsy, or another condition may affect brain function. It may also be used before brain surgery to identify areas that should be protected.

How is the test performed?

You lie on a table inside an MRI scanner while images are taken. The scanner is noisy, and you may be asked to perform tasks such as tapping your fingers, moving your hands, or answering questions.

How do I prepare for the test?

Tell the imaging team about metal implants, medication patches, pregnancy, claustrophobia, or any other health concerns. You may be asked to avoid caffeine or nicotine if the scan includes brain activation tasks, and follow the facility's specific instructions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Results can show areas of altered or reduced brain activity, but they do not identify a specific condition by themselves. A radiologist and the ordering clinician interpret the images together with the medical history and other examinations. Planning information from fMRI is especially important when nearby healthy brain tissue must be preserved during surgery.

Short name

Brain fMRI without contrast

Frequently asked questions

Does this test use contrast dye?
The name indicates that it is performed without intravenous contrast. If your order includes a separate contrast-enhanced scan, follow the instructions provided by the imaging facility.
Is fMRI the same as a routine brain MRI?
Both use magnetic fields to create images, but fMRI also evaluates changes in blood flow and brain activity. A routine MRI primarily shows the brain's structure.
Will I feel anything during the scan?
The scan itself is painless, but the scanner can be loud and feel confining. Tell the team if you are anxious or unable to remain still, because children and some patients may receive sedation.
  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