1 Department of Computer Science and Software Engineering, Concordia University, Montreal, Québec Canada.
2 Department of Pediatrics, Division of Neurology, Sainte-Justine University Hospital Center, Montreal, Québec Canada.
3 Department of Surgery, Division of Neurosurgery, Sainte-Justine University Hospital Center, Montreal, Québec Canada.
4 Department of Surgery, University of Montreal Hospital Center (CHUM), Montreal, Québec Canada.

Epilepsy is a neurological disorder characterized by recurring seizures that can cause a wide range of symptoms. Stereo-electroencephalography (SEEG) is a diagnostic procedure where multiple electrodes are stereotactically implanted within predefined brain regions to identify the seizure onset zone, which needs to be surgically removed or disconnected to achieve remission of focal epilepsy. This procedure is complex and challenging due to two main reasons. First, as electrode placement requires good accuracy in desired brain regions, excellent knowledge and understanding of the 3D brain anatomy is required. Second, as typically multiple SEEG electrodes need to be implanted, the positioning of intracerebral electrodes must avoid critical structures (e.g., blood vessels) to ensure patient safety. Traditional SEEG surgical planning relies on 2D display of multi-contrast volumetric medical imaging data, and places a high cognitive demand for surgeons' spatial understanding, resulting in potentially sub-optimal surgical plans and extensive planning time (~ 15 min per electrode). In contrast, virtual reality (VR) presents an intuitive and immersive approach that can offer more intuitive visualization of 3D data as well as potentially enhanced efficiency for neurosurgical planning. Unfortunately, existing VR systems for SEEG surgery only focus on the visualization of post-surgical scans to confirm electrode placement. To address the need, we introduce the first VR system for SEEG planning that integrates user-friendly and efficient visualization and interaction strategies while providing real-time feedback metrics, including distances to nearest blood vessels, angles of insertion, and the overall surgical quality scores. The system reduces the surgical planning time by 91%.