Intraoperative MRI (iMRI)

What is an iMRI?

Intraoperative magnetic resonance imaging (iMRI) is an imaging scan that’s performed during a surgical procedure. An iMRI gives your surgical team a clear look at the structures, organs and tissues inside your body.

The iMRI can help your surgeon make sure that they’ve completely removed a tumor, for example. It can also reduce your risk of surgical complications, like having to undergo a second surgery to remove remaining tumor components that weren’t clearly visible during the surgery.

What’s the difference between an MRI and an iMRI?

The main difference between an MRI and an iMRI is when it happens. A healthcare provider will order an MRI to diagnose a condition or prepare for a procedure. An iMRI happens during a surgical procedure.

Why do surgeons use an iMRI?

Intricate procedures require detailed imaging as they’re happening. The iMRI helps your surgeon see your body more clearly than the human eye or a microscope can during surgery.

A common surgical procedure that involves an iMRI is a craniotomy. Other common procedures where your surgeon may use an iMRI include:

• Tumor removal (primary, brain, pituitary, etc.).
• Deep brain stimulation implant.
• Movement conditions surgeries like Parkinson’s disease.
• Glioma removal.
• Epilepsy surgery.

How does an iMRI work?

Magnetic resonance imaging (MRI) is a device that takes a picture using magnets and radio waves. Your surgical team will use an MRI machine to take an iMRI picture during surgery. You won’t feel it. You’ll be under an anesthetic and likely asleep while this happens.

More than half of the human body is made up of water. Water consists of hydrogen and oxygen atoms. Within the hydrogen atom is a component called a proton. Protons carry an electric charge and spin around within the atom.

An MRI passes an electric current through coils within the device that create a short-term magnetic field in your body. This causes the protons in your body to line up and point toward the magnets in the MRI device. It’s similar to how a needle on a compass points north because it’s lining up with the Earth’s magnetic field.

The MRI device then sends radio waves through the magnetic field. This is the shutter on the MRI taking a picture. As you’d press a button to take a picture on a camera, short bursts of radio waves break the alignment of protons within the magnetic field. When the bursts end, the protons realign. A scanner picks up the changes in the protons and sends them to a computer, which creates an image out of them.

How do I prepare for an iMRI?

You won’t need to specifically prepare for an iMRI because it happens during a surgical procedure. Your surgical team will make sure you and the surgical room are ready for the imaging test when it’s time. Instead, you can prepare for surgery by following your surgeon’s instructions.

You’ll be under an anesthetic during the procedure, most often general anesthesia, where you’ll be asleep. While the MRI is painless, it’s noisy. If you’re having an awake procedure (with an anesthetic that doesn’t put you to sleep), your care team will help you prepare and make sure you’re comfortable while the imaging scan happens.

Let your healthcare provider know if you’re pregnant or have any metal within your body before surgery. Metal could include a pacemaker or implants. As an MRI uses magnets, any metal within or on your body could move or malfunction. This is a safety hazard. Your care team will follow special instructions to make sure your procedure is safe.

Make sure you remove all of your jewelry or other metals from your body before your procedure. This could include earrings, underwire bras or hairpins, for example.

What are the benefits of an iMRI?

The benefits of an iMRI include:

• Seeing an area of your body in close detail.
• Seeing these details in real-time.
• Assessing changes to the affected area during surgery.
• Avoiding and preventing complications.
• No radiation (it doesn’t harm you).

When will my surgeon see the results of an iMRI?

Your surgeon will be able to see an iMRI picture a few seconds to minutes after the scan. This helps them move forward with the procedure in real time without delay.