SCALP-RECORDED EEG LOCALIZATION IN MRI VOLUME DATA

Scalp-recorded EEG is a noninvasive and widely available tool for stud ying normal and dysfunctional human neurophysiology with unsurpassed t emporal resolution, However, scalp-recorded EEG data is difficult to c orrelate with anatomy, and most current display and neural source esti mation algorithms are based on unrealistic spherical or elliptical mod els of the head. It is possible to measure the positions of electrodes on the patient's scalp, and to register those electrode positions int o the space of a high-resolution MRI volume, and to then use the patie nt-specific anatomy as the basis for display and estimation of neural sources. We use a surface matching algorithm to register digitized ele ctrode and scalp surface coordinates to a three-dimensional MRI volume . This study uses fiducial markers in phantom and volunteer studies to quantitatively estimate the accuracy of the electrode registration me thod. Our electrode registration procedure is accurate to 2.21 mm for a realistic head phantom and accurate to 4.16 mm on average for five v olunteers. This level of accuracy is considered within acceptable limi ts for clinical applications.