MEG/MRI

1. Magnetoencephalography Combined with MRI
( Emerging Biological Marker for Neurodegenerative disorders and PTSD)
MagnetoEncephaloGraphy (known as MEG) is a technique used to study brain activity. In the outermost
layer of the cerebral cortex there are around 10,000,000,000 neuronal cells. The signals that allow these
cells to communicate with one another use electrical currents. The electrical currents also have
magnetic fields associated with them and this is what is detectable using the MEG system. The
measurement of these ‘neuromagnetic fields' allows us to determine both when and where the
activation is occurring in the brain.
Magnetoencephalography (MEG) scan is the newest technique used to precisely map functional areas of
the brain. The MEG scanner generates a real-time movie of brain activity as a patient is asked to do
specific exercises.
How does MEG work?
Here is a very short video about how MEG works:
http://www.youtube.com/watch?v=KoS2UXr0yMg
The alterations in brain function that are detected with MEG, especially those in the temporal regions,
are significantly correlated with the relative volume of the lateral and medial temporal lobes. This
establishes a link between altered brain structure and altered brain function measured in two different
modalities (i.e., MRI and MEG).
Why MEG and not fMRI?
1. fMRI measures neuronal activity indirectly, relying on the hemodynamic response.
2. MEG has a much greater temporal resolution (it is better able to measure such subtle delays in
local and regional responses).
3. Metallic fragments in the body are not contra-indications for the scan
Read more:
http://www.hindawi.com/journals/ijad/2011/280289/
What about a combination of MEG and fMRI?
The alterations in brain function that are detected with MEG, especially those in the temporal regions,
are significantly correlated with the relative volume of the lateral and medial temporal lobes. This
establishes a link between altered brain structure and altered brain function measured in two different
modalities (i.e., MRI and MEG).
It has been demonstrated recently that simultaneous visualization using MRI and MEG is possible. This
can be done with the help ofa hybrid multichannel helmet-shaped MEG-MRI device, which is capable of
simultaneously recording ultra-low-field MRI and MEG.

2. Researchers at Aalto University in Finland have developed the world’s first device designed for mapping
the human brain that combines whole-head magnetoencephalography (MEG) and magnetic resonance
imaging (MRI) technology. MEG measures the electrical function and MRI visualizes the structure of the
brain. The merging of these two technologies has the ability to produce unprecedented accuracy in
locating brain electrical activity non-invasively.
Here is a video of this very new technique:
http://www.youtube.com/watch?v=cfb87-lrimA
In the US, The Hoglund Brain Imaging Center (HBIC), University of Kansas, wasrecently awarded a
federal High End Instrumentation grant to purchase new state-of-the-art equipment that combines MEG
and MRI.
http://www.kumc.edu/school-of-medicine/hoglund-brain-imaging-center/facilities-and-resources.html
MEG in PTSD:
MEG has been used in the diagnosis and management of PTSD for a few years. The research conducted
by Georgopouloset al. (2010) opened an avenue for an objective diagnosis of PTSD and the potential for
evaluating the effectiveness of interventions of treatments.
This study involved 74 United States veterans who underwent magnetoencephalography (MEG) that for
the first time allowed scientists to objectively diagnose PTSD with a ninety percent accuracy rate. The
researchers were able to identify individuals who suffer from PTSD separately from healthy volunteers
in the study.
http://iopscience.iop.org/1741-2552/7/1/016011
The MEG combined with Diffusion Tensor Imaging (fMRI) might increase the accuracy of diagnosing
PTSD beyond 90% which is accomplished by MEG alone.Here is a slide show presentation byMingxiong
Huang (PhD) from University of San Diego along with VASDHS and NMCSD:
http://www.slideshare.net/adonissfera/magnetoencephalography-meg-and-diffusion-tensor-imaging
ADONIS SFERA, MD