Current developments in multimodal imaging are stemming from the merging of two imaging devices into one, thereby combining the benefits that each device has to offer. One such example is a hybrid created from the combination of an Magnetoencephalography (MEG) with Magnetic Resonance Imaging (MRI). The results are showing that sometimes one and one are more than two.
Development of Hybrid MEG-MRI
When multimodal imaging begun, the data was provided sequentially. Nowadays, with hybrid systems that are already in clinical use, such as PET-MRI and PET-CT, the imaging from two or more devices is done at the same time.
The hybrid MEG-MRI is still under development. In order to create one device out of these two systems it is necessary to combine them physically and integrate the measurement outputs that each of them produces. The MRI and MEG each provide different types of data; the MRI provides visual structural imaging information while the MEG provides non-visual real-time information on neuronal activity. MRI can also measure functionality, in what is called functional MRI (fMRI), as the tissue properties imaged by the MRI can change over time, but this is problematic and not completely reliable.
The combination of the MEG spatiotemporal information with the MRI structural data produces a 3D image of the brain electrical activity that is displayed tomographically. A good analogy for this combination would be to think of the MRI as sight and the MEG as hearing, combining the two senses gives us a much more comprehensive representation of the reality around us.
Challenge in Merging the MEG with the MRI
The main challenge in the merge of the MEG and MRI is that they each have different magnetic field strengths. However, there appears to be a solution to this discrepancy; experiments held at Berkeley University and Los Alamos National Laboratory have shown that ultra-low-field MRI can produce clinically relevant information. Furthermore, ultra-low-field MRI does not have the possible distortions of the standard high-field MRI and due to the unique relaxation time characteristic of low magnetic fields, new information is shown that previously was not accessible.
Advantages of the Hybrid MEG-MRI
When the MRI and MEG are combined, the information that was previously obtained in two examinations can be obtained in one session, saving time and money. In addition, the data produced is more accurate and reliable regarding the location of the electrical activity in the brain.
The hybrid MEG-MRI is safe, quiet and inexpensive. Because of the low magnetic field it may be possible to examine patients with a pacemaker, and because of the physical structure it is friendlier for obese patients who cannot fit into the standard MRI.
One of the development paths for multimodal imaging is hybrid systems, thereby significantly enhancing the data that was previously obtained from each system individually. Moreover, the process of adapting each system for the merge is acting as a stimulus for discovery of new possibilities within the system in itself, as can be seen with the ultra-low-field MRI. MEG-MRI provides a more reliable method to obtain structure and functional information simultaneously, and may in the future be the solution when this type of information is required.