Abstracts

Rationale: Intracranial EEG recoding using subdural grids or depth electrodes is necessary for resective epilepsy surgery in some cases for localizing the epileptogenic zone. The knowledge of the cortical anatomy underlying these grids is crucial for a successful surgery. The goal of this study was to assess the usefulness of 3D printing techniques for surgical planning to provide information about electrode location in relation to details of the cortical anatomy easily recognizable for neurosurgeons during resective surgery.Methods: Pre-operative MRI and post-operative CT data were obtained retrospectively from 4 patients that underwent intracranial EEG monitoring study and resective surgery thereafter. The intracranial electrodes were extracted from the CT scans and then co-registered to the MRI. 3D surface files of the brain with co-registered electrodes were created and rendered. Solid individualized brain models were created and printed using a 3D printer. The accuracy of the intracranial electrodes localization was assessed by visually comparing the focal electrodes on the surgical photographs from skull window to the same electrodes on the surface of the 3D printed brain. The time for imaging processing and 3D printing was also measured.Results: The grids from the four cases were placed on the lateral frontal lobe; lateral, anterior, and interior temporal lobe; lateral and mesial occipital lobe; and partial lobe. All electrodes from these grids were printed on the 3D printed brain surface. Through the visual comparison, the electrodes located in the surgical fields from the surgical photographs were matched to the electrodes on the surface of the 3D printed brain. The electrodes on the surface of the 3D printed brain were easily recognizable and reviewed from different angles (Figure 1 and 2). The time for imaging processing before 3D printing was about four hours, the 3D printing took about three hours. The main challenge for the 3D printing is from the post-operative CT and pre-operative MRI co-registration. The focal bleeding, edema, or fluid collection during grids placement may make the CT and MRI co-registered imperfectly. Some of the electrodes may fallout of the 3D printed brain surface, which needed extra imaging processing steps to put them back on the brain surface, which may affect the accuracy.Conclusions: 3D printing is a useful tool for intracranial EEG electrodes localization by providing relatively realistic information about electrode location in relation to details of the cortical anatomy, which is helpful in individualized planning for resective epilepsy surgery. Future studies are warranted to improve the post-operative CT and pre-operative MRI co-registration, to shorten the imaging processing time.