This document addresses magnetic source imaging (MSI) and magnetoencephalography (MEG).

Note: Please see the following related document for additional information:

• CG-MED-46 Electroencephalography and Video Electroencephalographic Monitoring

Clinical Indications

Medically Necessary:

Magnetoencephalography (MEG) is considered medically necessary for:

1. Preoperative evaluation of individuals with intractable focal epilepsy to identify and localize area(s) of epileptiform activity when other techniques are indeterminate; or
2. Preoperative localization of eloquent cortex prior to surgical resection of any of the following:
   1. Brain tumor in order to maximize preservation of eloquent cortex; or
   2. Vascular malformations in order to maximize preservation of eloquent cortex.

Magnetic source imaging (MSI) is considered medically necessary for:

1. Preoperative evaluation of individuals with intractable focal epilepsy to identify and localize area(s) of epileptiform activity when other techniques are indeterminate; or
2. Preoperative localization of eloquent cortex prior to surgical resection of any of the following:
   1. Brain tumor in order to maximize preservation of eloquent cortex; or
   2. Vascular malformations in order to maximize preservation of eloquent cortex.

Not Medically Necessary:

Magnetoencephalography (MEG) and magnetic source imaging (MSI) are considered not medically necessary for all other indications.