Precise targeting of tumors, lesions, and anatomical structures with a probe, needle, catheter, or electrode inside the brain based on preoperative CT/MRI are nowadays standard tasks in stereotactic neurosurgery. Incorrect placement of the surgical tool may carry a significant hemorrhagic risk and neurological deficits. Currently, planning an insertion trajectory is done manually on 2D image slices, which is complex, time-consuming, and is user-dependent.
A method for planning safe straight insertion trajectories for minimally invasive neurosurgery that minimizes the expected risk of vascular and neurological damage due to incorrect tool placement.
We have developed a new preoperative planning method and computer software designed to reduce the risk of candidate trajectories for straight rigid tool insertion in image-guided keyhole neurosurgery. Trajectories are computed based on the surgeon-defined target and a candidate entry point area on the outer head surface on preoperative CT/MRI scans. A multi-parameter risk card provides an estimate of the risk of each trajectory according to its proximity to critical brain structures. Candidate entry points in the outer head surface areas are then color-coded and displayed in 3D to facilitate selection of the most adequate point. The surgeon then defines and/or revised the insertion trajectory using an interactive 3D visualization of surrounding structures. A safety zone around the selected trajectory is also computed to visualize the expected worst-case deviation from the planned insertion trajectory based on tool placement errors in previous surgeries.
A total of 120 surgical trajectories were collected from 5 surgeons, 8 targets and 3 methods. The risk scores improved by 76% (std=11.6%), the mean distance of a trajectory from nearby blood vessels increased by 1.6mm (std=0.5), from 0.6mm to 2.2mm (243%). The initial trajectories were changed in 85% of the cases based on the risk score and the trajectory distance from blood vessels.
Participants: RR. Shamir, M. Trope, L. Joskowicz, CASMIP Lab. G. Rosenthal, A. Mayer, N. Levin, A. Bick, Y. Shoshan, Hadassah University Hospital, Ein-Karem, Jerusalem.
Publications: Reduced risk trajectory planning in image-guided keyhole neurosurgery: method and experimental results. RR. Shamir et al, Medical Physics 39:2885-2896, 2012.. The role of automatic computer-aided surgical trajectory planning in improving the expected safety of stereotactic neurosurgery. M. Trope et al. Int. J. Computer Aided Radiology and Surgery, 2015.