Cerebrovascular segmentation and planning of depth electrode insertion for epilepsy surgery

Depth electrodes are inserted in the brain to locate the epileptogenic zone without craniotomy, but there is risk of surgical hemorrhage. Preoperative planning is required to mitigate this risk. A preoperative imaging, segmentation and three dimensional (3D) visualization procedure was developed to provide neurosurgeons with cortical and vascular anatomy information for surgical planning and neuronavigation.

Cerebral vascular imaging was performed with phase-contrast magnetic resonance angiography (PC-MRA). Fuzzy c-means was performed to extract brain parenchyma from the PC-MRA images. A multi-scale vessel enhancement filter and thresholding process were combined to segment the vasculature and suppress background noise in the PC-MRA images. Finally, 3D visualization of the vasculature and cortical structures was implemented using volume rendering.

Quantitative and qualitative validation of the vascular segmentation method were done. Using manual vascular segmentation as the gold standard, our method produced a satisfactory result: sensitivity was as high as 90 % at a specificity level of 95 %. Moreover, comparing the 3D visualizations of the vasculature and cortical structure for 4 patients with their respective intraoperative craniotomy photographs showed high levels of similarity.

A new automated segmentation and visualization procedure provides sufficient and accurate cortical and vascular anatomy information compared to intraoperative photographs. This method has potential to assist neurosurgeons with planning and neuronavigation for depth electrode insertion with avoidance of cerebral hemorrhage.