Editing Magnetoencephalography (section)

=== Magnetic source imaging ===
The source locations can be combined with [[magnetic resonance imaging]] (MRI) images to create magnetic source images (MSI).  The two sets of data are combined by measuring the location of a common set of [[Fiduciary marker|fiducial points]] marked during MRI with lipid markers and marked during MEG with electrified coils of wire that give off magnetic fields.  The locations of the fiducial points in each data set are then used to define a common coordinate system so that superimposing the functional MEG data onto the structural MRI data ("[[coregistration]]") is possible.

A criticism of the use of this technique in clinical practice is that it produces colored areas with definite boundaries superimposed upon an MRI scan: the untrained viewer may not realize that the colors do not represent a physiological certainty, not because of the relatively low spatial resolution of MEG, but rather some inherent uncertainty in the probability cloud derived from statistical processes.  However, when the magnetic source image corroborates other data, it can be of clinical utility.