Localizing ECoG electrodes on the cortical anatomy without post-implantation imaging

Area of Science:

• Neurosurgery
• Neuroscience
• Medical Imaging

Background:

• Electrocorticographic (ECoG) grids are crucial for mapping eloquent cortex during epilepsy surgery.
• Accurate electrode localization is vital for correlating ECoG signals with brain anatomy in research.
• Current localization methods often rely on post-operative imaging or intra-operative photographs, which are not always available.

Purpose of the Study:

• To develop and validate a novel method for co-registering ECoG electrodes to cortical anatomy.
• To enable electrode localization using only pre-operative MRI, a neuronavigation device, and fiducial markers.
• To provide a valuable tool for neuroscientific research, particularly in single-stage surgical scenarios.

Main Methods:

• A fiducial-based co-registration technique was developed using pre-operative MRI and a clinical neuronavigation system.
• The method's accuracy was validated by comparing its results to established methods using post-grid implantation imaging (MRI-CT) and intra-operative photographs.
• The technique was applied intra-operatively during real-time mapping of eloquent cortex in a single-stage surgery.

Main Results:

• The fiducial-based method demonstrated agreement with the MRI-CT method within an average of 8.24 mm in 3D.
• Comparison with intra-operative photographs showed an average discrepancy of 2.7 mm in a 2D coordinate system.
• The method successfully acquired valuable ECoG signals intra-operatively without post-operative imaging.

Conclusions:

• The developed fiducial-based method provides accurate ECoG electrode localization to cortical anatomy.
• This technique is particularly useful for intra-operative, single-stage surgeries where post-operative imaging is unavailable.
• The method enhances the value of ECoG data for neuroscientific research by enabling precise anatomical correlation.