Rapid and Accurate Anatomical Localization of Implanted Subdural Electrodes in a Virtual Reality Environment

Aim: An accurate and rapid anatomical localization of implanted subdural electrodes is essential in the invasive diagnostic process for epilepsy surgery. The aim of this study is to demonstrate our experience with a three-dimensional (3-D) virtual reality simulation software (Dextroscope®) in the postoperative localization of subdural electrodes implanted for invasive electroencephalography (EEG) recording and neurostimulation.

Methods: Postoperative thin-slice computed tomography scans were coregistered to preoperative 3-D magnetic resonance imaging in the Dextroscope environment in 10 patients. Single electrodes as well as contacts were segmented and their positions in relation to individual brain anatomy were obtained by means of 3-D reconstruction and 3-D stereoscopic visualization within the Dextroscope environment. The spatial accuracy was tested comparing the positions of the electrode contacts as shown in the 3-D reconstruction with intraoperative photographs. Image processing time was also recorded.

Results: The 3-D stereoscopic reconstruction provided solid and accurate representation of the implanted electrodes with highly detailed visualization of the underlying anatomical sites. The mean absolute difference between 3-D reconstruction and intraoperative photographs was 2.4±2.2 mm and thereby smaller than the diameter of the electrode contacts (i.e., 4 mm). The processing time to obtain the 3-D reconstructions did not exceed 15 minutes.

Conclusions: The results indicate that the 3-D virtual reality simulation software used in our series is a useful tool for rapid and precise localization of subdural electrodes implanted for invasive EEG recordings.