Magnetoencephalography/magnetic source imaging in the assessment of patients with epilepsy

Magnetoencephalographic (MEG) dipole source localization is a particularly promising new tool for noninvasive presurgical evaluation of epileptogenic foci. It is potentially more accurate than EEG localization techniques because magnetic fields are not attenuated or distorted by the skull and scalp, which allows cerebral sources to be modeled more simply. MEG spike and seizure sources are routinely co-registered with the patient's brain MRI for clinical interpretation. This has been called magnetic source imaging. Numerous studies have shown that MEG localization of foci agreed with lesion position, depth electrode and ECoG data, PET and MRI findings, and surgical success. The recent development of whole head sensor arrays has greatly enhanced the ease with which epileptiform magnetic fields can be recorded and analyzed.