Functional MRI

By: Andrew Yee

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What are Functional MRIs?

A functional MRI is a piece of technology that forms a picture of what is happening inside the patient’s head. This is often done before surgery to determine where a tumor is. These images are then sent to the neurosurgeon, who can evaluate the specific brain region that requires surgery and what parts to avoid. It is pain-free and often plays a pivotal role in brain surgery.

Purpose of an fMRI

An fMRI works by using the same technology as an MRI. To take the image, the patient will lie in a tube-shaped magnet that uses the body’s neurons to measure blood flow. This happens because when the brain is more active, it will send out more electrical signals. By performing an fMRI, we can measure the oxygen levels in the blood. If oxygen levels go up, we can measure the surrounding blood vessels and the resulting change in blood flow (Pederson, 2021).

How Does the fMRI Work?

Once inside the scanner, patients are given activities to perform. This can include simple tasks such as thinking, memorizing, or gripping. The active regions of the brain will then light up on the scanner, and by finding out what places are active during these actions, the surgeon will know what neurotransmitting pathways to avoid (Yale, 2022).

A fMRI can last anywhere between 40 to 55 minutes and is often painless. However, since you are in an enclosed space, some people may experience claustrophobia (Pederson, 2021).

Pre fMRI

Some places may require you to change into their hospital gown before the MRI. Guidelines on what to eat will be provided, but you can safely assume to consume your daily diet and medications unless told otherwise. Some fMRIs may include injections of materials to help isolate the neurons and create the picture (Radiological).

If you are pregnant or have other medical conditions, consult your doctor. Leave all jewelry at home or remove them before the scan occurs. Metal will interfere with the magnetic fields surrounding your body. If you have metal implants, consult your doctor.

Post fMRI

After performing the fMRI, you will collect your belongings and leave the scanning area. The doctor will receive a report of your fMRI results (Pederson, 2021). A fMRI should usually be performed 1 to 2 days before the surgery. If surgery does not immediately follow, you should meet with a doctor to determine the best form of surgery and how much of the brain they should remove (Yale, 2022).

An fMRI comes with a variety of benefits, but it also has some negatives:


It is a noninvasive technique that does not expose you to radiation

It can help doctors evaluate the structures and processes of your organs

Can detect abnormalities and assess organ structure

No known health risks associated with the procedure


Possibility for an allergic reaction to the injection

Anxiety and stress may produce movements that cause the tests to prolong

Generally more expensive than other imaging tests

Possible risks if pregnant

Various issue, including irregular heartbeat or life support equipment, can affect image quality


A functional MRI is often a feasible option for patients requiring brain surgery in the following days. The fMRI allows doctors to map out your brain and its functions to determine what they can cut and remove from the brain. The fMRI does this by measuring the oxygen in your brain by examining the blood vessels as your brain goes through a series of tests that determine your brain’s organs and their functions. It is often painless but can easily be affected by twitching movement, so remain still during the exam. An fMRI is a huge part of brain surgery.


Pedersen, T. (2021, December 13) What is fMRI? Uses, how it works, duration, and what to expect. Psych Central. Retrieved February 11, 2023, from

Radiological Society of North America (RSNA) and American College of Radiology (ACR) (n.d.). Functional MRI (fMRI). Retrieved February 5, 2023, from

Yale Medicine (2022, August 13). Functional MRI of the brain. Yale Medicine. Retrieved February 1, 2023, from

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