Development and external validation of a mixed-reality aneurysm clipping simulator

Abstract

Nowadays, surgical treatment of cerebral aneurysms remains one of the most demanding disciplines in neurosurgery. The increasing shift toward endovascular interventions leads to a decline in open surgical cases. This fact leaves residents and young neurosurgeons with fewer training opportunities and limited to complex and high-risk aneurysms. There is a growing need for realistic simulation tools to enhance neurosurgical training and preoperative planning. We developed and externally validated a patient-specific mixed-reality simulator for cerebral aneurysm clipping, during the research project "Medical EDUcation in Surgical Aneurysm Clipping (MEDUSA)". Our approach combines physical phantoms of the skull and brain tissue with virtual intracranial blood vessels, including a virtual intracranial aneurysm. Real surgical instruments provide an immersive training environment featuring integrated blood flow simulation for evaluating clipping strategies. A life-sized skull with silicone brain lobes is mounted in a standard neurosurgical head clamp. Optical tracking synchronizes the position of a real clip applier and an emulated surgical microscope with the corresponding virtual environment, allowing true mixed-reality interaction. After aneurysm clipping, blood flow is automatically simulated to assess residual aneurysms or stenoses of the parental vessels. We conducted an external validation with 40 neurosurgeons at two international events. Participants completed a 32-item questionnaire evaluating face and content validity on a 5-point Likert scale. Participants' surgical experience ranged from novice to expert (> 15 years). Average ratings for simulator realism and educational value were high, with mean scores between 3.13 and 4.25. The highest ratings were for the blood flow simulation (4.25) and the simulator's potential for preoperative planning (4.20). Most participants agreed that the physical and virtual components were valuable and that the simulator should be integrated into neurosurgical training and standard surgical workflows. Our mixed-reality simulator achieved robust face and content validity among a diverse group of neurosurgeons. Combining real surgical instruments with a deformable virtual aneurysm model, including blood flow simulation, offers a high level of realism and immediate objective feedback.

Keywords: Aneurysm clipping; Blood flow simulation; Mixed-reality; Validation.

Fig. 1

Components of the Medusa simulator. (A) mixed reality simulator; (B) detailed view of patient phantom showing the clamped head and artificial skull and brain; (C) modified clipping forceps with reflective markers; (D) optical tracking camera; (E) virtual view of the operating field (middle cerebral artery aneurysm)

Fig. 2

Schematic overview of the hardware and software components used in the Medusa simulator

Fig. 3

Comparison between physical and virtual world. (A) View of the physical operating field; (B) View of the virtual operating field showing the accurate correspondence between the two. Note that the clip only exists in the virtual world; (C) Scene from a real middle cerebral artery aneurysm clipping surgery; (D) Virtual clipping of the same aneurysm reconstructed from image data of the patient; (E) ICG angiography showing blood perfusion after clipping; (F) visualization of streamlines and pressure distribution obtained from simulation of blood flow through the clipped aneurysm model

Fig. 4

Virtual blood flow simulation to evaluate a specific clipping strategy. The upper row shows the clip–aneurysm complex without blood flow simulation, while the lower row presents the corresponding blood flow simulations. Different scenarios are illustrated: pre-clipping (A, B), residual aneurysm (C, D), critical M2 stenosis (E, F), and a regular post-virtual clipping result (G, H)

Fig. 5

Schematic overview of the processing pipeline for obtaining patient-specific 3D models from image data. Typically, the skull is extracted from CT, the brain is extracted from MRI and the blood vessels are extracted from DSA scans. The deformable arterial wall in the region close to the aneurysm requires additional steps, such as the definition of in- and outflow planes and separation of the aneurysm sac

Fig. 6

Mean scores for face validity of patient phantom and virtual environment

Fig. 7

Mean scores for face validity of simulator environment and general aspects

Fig. 8

Mean scores for content validity of the mixed reality clipping simulator