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Home Health Library Tests and Procedures Intraoperative magnetic resonance imaging (iMRI)

Intraoperative magnetic resonance imaging (iMRI)

Find out how neurosurgeons use intraoperative magnetic resonance imaging (iMRI) during brain surgery.


Intraoperative magnetic resonance imaging (iMRI) is a procedure that creates images of the brain during surgery. Neurosurgeons rely on iMRI to guide them in removing brain tumors and treating other conditions such as epilepsy.

Advantages of iMRI

Imaging tests are used to plan brain surgery, but real-time images created with iMRI during surgery are crucial to:

  • Locate changes if the brain has shifted. The brain often shifts during surgery, which makes pre-surgical imaging not exactly precise. Imaging with iMRI during the operation helps to provide surgeons with the most accurate information.
  • Distinguish between healthy brain tissue and tumors. It can be difficult to distinguish the edges of a brain tumor and separate healthy tissue from tissue that needs to be removed. Imaging with iMRI during surgery helps confirm successful removal of the entire brain tumor.
  • Protect critical structures. A procedure called laser interstitial thermal therapy (LITT) allows surgeons to treat epilepsy by heating tissue and making it inactive. This disrupts seizures through a minimally invasive approach. By using iMRI to monitor brain temperature, surgeons are able to keep temperatures low enough to avoid injury during the procedure. In MR-guided ultrasound, surgeons can focus ultrasound energy on areas of the brain causing epilepsy without performing surgery.

    Intraoperative MRI allows surgeons to achieve a more complete removal of some brain tumors. For this reason, iMRI has become standard for many operations to remove certain brain tumors.

How iMRI works

MRI uses a magnetic field and radio waves to create detailed images of the organs and tissues in your body. MRI is especially helpful for imaging the brain.

To use MRI technology during surgery, surgeons use special imaging systems and operating rooms, including:

  • Portable iMRI devices, which are moved into the operating room to create images.
  • Nearby iMRI devices, which are kept in a room near the operating room. This way, healthcare professionals can easily move you to the specially designed room for imaging during your surgery.

At certain points in your operation, the surgeon may request imaging with iMRI. When and how often the surgeon creates images during surgery depends on your procedure and your condition.

Uses for iMRI

Intraoperative MRI is used to assist in surgery to treat:

  • Brain tumor.
  • Dystonia.
  • Epilepsy.
  • Essential tremor.
  • Glioma.
  • Neuropsychiatric disorders.
  • Parkinson's disease.
  • Pediatric brain tumors.
  • Pituitary tumors.

Why it's done

Surgeons use iMRI to assist in procedures that treat a variety of brain tumors. Surgery is often the first step to treat a tumor that can be removed without causing neurological damage. Some tumors have a clearly defined shape and can be removed easily.

In addition, surgeons use iMRI to place deep brain stimulators to treat epilepsy, essential tremor, dystonia and Parkinson's disease. iMRI also is used to assist in surgery for some brain conditions. They include a bulge in a blood vessel, known as an aneurysm, and tangled blood vessels, known as arteriovenous malformation. The technology also may be used in surgery to treat mental health disorders.

During these procedures, iMRI allows surgeons to monitor brain activity. It helps surgeons check for bleeding, clots and other complications. Intraoperative MRI can help prevent damage to surrounding tissue and protect brain function. It also can help address complications earlier. The technology may reduce the need for additional operations. For cancer surgery, iMRI helps surgeons ensure that the entire tumor has been removed.

What you can expect

Surgeons use iMRI to create real-time brain images. At certain points during an operation, the surgeon may want to see certain images of the brain. MRI uses a magnetic field and radio waves to create detailed brain images.

To use MRI technology during surgery, healthcare professionals may bring a portable iMRI machine into the operating room to create images. Or they may keep the iMRI machine in a room nearby so surgeons can easily move you there for imaging during the procedure.

iMRI cannot be used in patients with most pacemakers, cochlear implants, and metal joints or certain implants.

Last Updated: April 4th, 2024