Sébastien Delorme

NeuroTouch: A physics-based virtual simulator for cranial microneurosurgery training

BACKGROUND: A virtual reality neurosurgery simulator with haptic feedback may help in the training and assessment of technical skills requiring the use of tactile and visual cues. OBJECTIVE: To develop a simulator for craniotomy-based procedures with haptic and graphics feedback for implementation by universities and hospitals in the neurosurgery training curriculum. METHODS: NeuroTouch was developed by a team of more than 50 experts from the National Research Council Canada in collaboration with surgeons from more than 20 teaching hospitals across Canada. Its main components are a stereovision system, bimanual haptic tool manipulators, and a high-end computer. The simulation software engine runs 3 processes for computing graphics, haptics, and mechanics. Training tasks were built from magnetic resonance imaging scans of patients with brain tumors. RESULTS: Two training tasks were implemented for practicing skills with 3 different surgical tools. In the tumor-debulking task, the objective is complete tumor removal without removing normal tissue, using the regular surgical aspirator (suction) and the ultrasonic aspirator. The objective of the tumor cauterization task is to remove a vascularized tumor with an aspirator while controlling blood loss using bipolar electrocautery. CONCLUSION: NeuroTouch prototypes have been set up in 7 teaching hospitals across Canada, to be used for beta testing and validation and evaluated for integration in a neurosurgery training curriculum. ABBREVIATIONS: DOF, degrees of freedom

Computer prediction of friction in balloon angioplasty and stent implantation

The success of balloon angioplasty and stent implantation depends on a balance between two conflicting objectives: maximization of artery lumen patency and minimization of mechanical damage. A finite element model for the patient-specific prediction of balloon angioplasty and stent implantation is proposed as a potential tool to assist clinicians. This paper describes the general methodology and the algorithm that computes device/artery interaction during stent deployment. The potential of the model is demonstrated with examples that include artery model reconstruction, device deployment, and prediction of friction on the arterial wall

A Computer Model of Soft Tissue Interaction with a Surgical Aspirator

Surgical aspirators are one of the most frequently used neurosurgical tools. Effective training on a neurosurgery simulator requires a visually and haptically realistic rendering of surgical aspiration. However, there is little published data on mechanical interaction between soft biological tissues and surgical aspirators. In this study an experimental setup for measuring tissue response is described and results on calf brain and a range of phantom materials are presented. Local graphical and haptic models are proposed. They are simple enough for real-time application, and closely match the observed tissue response. Tissue resection (cutting) with suction is simulated using a volume sculpting approach. A simulation of suction is presented as a demonstration of the effectiveness of the approach.

Virtual Reality Simulator: Demonstrated Use in Neurosurgical Oncology

Background. The overriding importance of patient safety, the complexity of surgical techniques, and the challenges associated with teaching surgical trainees in the operating room are all factors driving the need for innovative surgical simulation technologies. Technical development. Despite these issues, widespread use of virtual reality simulation technology in surgery has not been fully implemented, largely because of the technical complexities in developing clinically relevant and useful models. This article describes the successful use of the NeuroTouch neurosurgical simulator in the resection of a left frontal meningioma. Conclusion. The widespread application of surgical simulation technology has the potential to decrease surgical risk, improve operating room efficiency, and fundamentally change surgical training.

Characterization of suction and CUSA interaction with brain tissue

Basic and ultrasonic aspirators are the most commonly used surgical devices in neurosurgery. In this study, a tissue removal model was adjusted to experimental results of interaction between ultrasonic aspiration and brain tissue-mimicking material. Tissue grasping with a basic aspirator was also further investigated on fresh calf brain tissue obtained from several animals. Tests were conducted on both grey and white matter. The simulation screenshots, compared with the experimental photos, are presented to demonstrate the results.

Endoscopic third ventriculostomy on a microneurosurgery simulator

Endoscopic third ventriculostomy is a procedure used to treat hydrocephalus by making a perforation in the floor of the third ventricle of the brain under endoscopic guidance. We report on our initial experience in developing an endoscopic third ventriculostomy simulator for neurosurgery residents, including the definition of the simulation content and integration on NeuroTouch, a simulator for microneurosurgery training. The simulator includes exercises in which the trainee is asked to choose the location of the burr hole and the orientation of the trajectory to the foramen of Monro, or is required to find the third ventricle with a neuro-endoscope and perforate its floor. The simulator provides feedback on trainee performance either graphically or using quantitative metrics. The simulator allows easily switching from endoscopic third ventriculostomy mode to microscopic craniotomy mode using a retractable stereoscope based on a single screen and mirrors, detachable plastic heads, and quick-connect tool handles to give more realistic haptic feedback.

Effect of Deformation Rate on the Mechanical Properties of Rectangular and Cruciform Arterial Samples: Uniaxial and Biaxial Testing

The elastic behavior of arteries is nonlinear when subjected to large deformations. In order to measure their anisotropic behavior, planar biaxial tests are often used. Uniaxial tests are also commonly used due to simplicity of data analysis, but their capability to fully describe the in vivo behavior of a tissue remains to be proven. Mechanical behaviour of arteries submitted to uniaxial or biaxial testing has been done previously [1–4]. Each one of these works was performed only at one deformation rate: 1 %/s [1, 3], 10 %/s [2], 1 Hz [4]; but those works do not show the behaviour of the arterial wall when it is submitted to different deformation rates. Thus, in this study we present the effect of deformation rate in the material properties (i.e. loading forces) of uniaxial and biaxial tests.© 2007 ASME

Constitutive Modelling of Endothelium Denudation for Finite Element Simulation of Angioplasty

This study aims at characterizing and modelling the effect of mechanical factors on endothelial denudation during angioplasty, such as normal force between balloon and artery, stretching of arterial walls, and relative displacement between contacting surfaces. Friction damage was applied to porcine aorta samples with different contact forces, relative displacements, and biplanar stretching conditions. After the tests, endothelium denudation was quantified by isolating and counting the remaining endothelial cells. Using multiple-regression analysis, a constitutive model is proposed for integration in finite element software. This model will help optimize balloon and stent deployment conditions to minimize the amount of damage to the endothelium, and eventually to reduce the occurrence of restenosis.