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Magnetoencephalography (MEG)


UC San Diego Health is one of only about 20 health care centers in the nation to perform magnetoencephalography (MEG), a non-invasive, painless and quiet technique for measuring the very weak magnetic fields in the brain, associated with the brain's electrical activity (neuronal firing).

MEG is the most advanced and accurate functional brain imaging technique currently available. Its advantages over other imaging technologies include:

  • Compared with fMRI, which uses blood flow as a proxy for neuronal activity, MEG provides direct information on the brain's electrical activity
  • Because the skull is transparent to magnetic waves, MEG can be used to precisely locate where brain activity is occurring, unlike electroencephalograms (EEGs)

Because of our expertise in the advanced procedure, we perform MEG scans for referring health care centers, including UCLA Health, UC Irvine Health, Kaiser-Permanente and Rady Children's Hospital – San Diego.

How We Use MEG to Improve Patient Care 

Led by Roland Lee, MD, our radiologists use MEG scans to:

  • Pre-surgically locate the sources of epileptic seizures to improve surgical outcomes of patients
  • Pre-surgically locate the eloquent cortex in patients undergoing brain surgery for trauma or epilepsy. The eloquent cortex refers to areas of the brain that, if removed, will result in loss of motor skills, sensory processing or linguistic ability, or paralysis.
  • Diagnose concussions and other traumatic brain injuries (TBIs), which cannot be diagnosed by MRI
  • Determine whether a patient is suffering from TBI or post-traumatic brain injury (PTSD), which are treated very differently
  • Map brain networks to study PTSD and other brain diseases
  • Conduct research on the efficacies of medications for schizophrenia

How to Prepare for Your Exam

No preparation is necessary. Specific instructions for your specific exam will be given to you at the time of the procedure.

What To Expect During Your Exam

  • You will enter a specially designed shielded room that blocks background electromagnetic radiation (from radio waves and cellular towers, among other sources). The shielded room creates a "quiet" space for measuring the brain's extraordinarily weak magnetic fields, about a billion times weaker than the Earth's magnetic field.
  • You will be asked to sit or lie down quietly in the scanner
  • We will place a helmet on your head
  • You receive no injections, nor will you be exposed to radiation. The scanner "listens to" (detects and records) your brain's own natural magnetic waves.
  • The procedure takes from five minutes to one hour depending on your test.

Appointments & Referrals


Sorrento Valley

  • 3510 Dunhill Street, San Diego