SIG | Magnetoencephalography (MEG): What Are Dipoles Anyway? What Source Location Means and Doesn't Mean

OVERVIEW:

This Special Interest Group examines the use of magnetoencephalography (MEG) in the pre-surgical evaluation for epilepsy treatment in three aspects: expectations, the science, and clinical interpretation.   

Several studies have demonstrated the utility of MEG, and in particular, the equivalent current dipole (ECD) in the epilepsy presurgical evaluation. However, for some neurologists and epileptologists, it can be challenging to understand what the ECD means and what it does not represent. This may create confusion between the “MEG user” (referring physician) and the “MEG reader” (MEG reading physician).  

Organized by the American Clinical MEG Society, this SIG features speakers who address issues of source interpretation from three different aspects:  

1. Expectations from a referring physician: how do I know where to refer? What makes a good MEG lab? What do I hope, and would like, the MEG report to contain? What is the meaning of the dipoles or other source localization? 
2. Science of source locations: What is source modeling and what are the common types used in clinical practice? What makes a spike model-worthy? 
3. Clinical interpretation: review orientation of sources and their anatomical localization. Discuss spike propagation and differentiating focal and generalized discharges. Discuss the interpretation of MEG and meaningful sources. Outline an appropriate MEG report based on the ACMEGS clinical practice guidelines.