A "Do It Yourself" Approach to Innovation: Neurosurgery Resident Production of 3D Printed Stereo EEG Models with Computer-aided Design and Digital Sculpting

Introduction: Stereo EEG (sEEG) placement is an important part of the workup of surgical epilepsy management. Decision making using the sEEG findings can be complex, involving multidisciplinary teams as well as patients and their families. Thus clear communication is crucial but sometimes challenging.

Patient-specific 3D printed models have traditionally been outsourced and expensive with potentially long turnaround times, but the improved accessibility and educational material on advanced software and 3D printing now make this work possible for surgeons to do themselves.

Methods: Two consecutive patients who underwent sEEG implantation were selected for modeling. Their pre-op MRIs and post-op CTs were merged, and electrode contacts were segmented using the programs 3D slicer and Freesurfer. Next, the computer-aided design (CAD) program Autodesk Fusion 360 was used to model the locations/trajectories of the sEEG electrodes. Finally, the 3D sculpting program Maxon ZBrush was used to clean the brain model and cut out electrode trajectories. The brain model was 3D printed on a Formlabs Form 3 stereolithography printer with clear resin.

Time spent on each step of the process was tracked to determine if it could be practical to produce such a model for a sEEG patient while their electrodes were in place.

Results: A workflow was devised to print optically transparent models of brains implanted with sEEG electrodes in 2-3 days. This workflow utilizes software from multiple disciplines including medical imaging, CAD, and 3D sculpting used in the entertainment industry.

After overcoming the learning curve of using these programs, the active user time was reduced from 24 hours on the first case to seven hours on the second.

Conclusion : Future models will include further anatomical definition with more advanced 3D modeling and printing techniques. Learning how to work with these programs as a surgeon has inspired several future projects.