Neurosurgical virtual reality simulation metrics to assess psychomotor skills during brain tumor resection.

PURPOSE: Virtual reality simulator technology together with novel metrics could advance our understanding of expert neurosurgical performance and modify and improve resident training and assessment. This pilot study introduces innovative metrics that can be measured by the state-of-the-art simulator to assess performance. Such metrics cannot be measured in an operating room and have not been used previously to assess performance. METHODS: Three sets of performance metrics were assessed utilizing the NeuroTouch platform in six scenarios with simulated brain tumors having different visual and tactile characteristics. Tier 1 metrics included percentage of brain tumor resected and volume of simulated "normal" brain tissue removed. Tier 2 metrics included instrument tip path length, time taken to resect the brain tumor, pedal activation frequency, and sum of applied forces. Tier 3 metrics included sum of forces applied to different tumor regions and the force bandwidth derived from the force histogram. RESULTS: The results outlined are from a novice resident in the second year of training and an expert neurosurgeon. The three tiers of metrics obtained from the NeuroTouch simulator do encompass the wide variability of technical performance observed during novice/expert resections of simulated brain tumors and can be employed to quantify the safety, quality, and efficiency of technical performance during simulated brain tumor resection. Tier 3 metrics derived from force pyramids and force histograms may be particularly useful in assessing simulated brain tumor resections. CONCLUSION: Our pilot study demonstrates that the safety, quality, and efficiency of novice and expert operators can be measured using metrics derived from the NeuroTouch platform, helping to understand how specific operator performance is dependent on both psychomotor ability and cognitive input during multiple virtual reality brain tumor resections.

Assessing performance in brain tumor resection using a novel virtual reality simulator.

PURPOSE: NeuroTouch is a virtual reality (VR) simulator developed for neurosurgical skill training. Validation demonstrating that the system is useful and reliable is required for formal adoption into training curriculums. Face and content validity have been demonstrated for some neurosurgical simulators, but construct validity remains difficult to establish. A pilot validation study was conducted for a NeuroTouch training exercise. METHODS: Participants completed the internal resection of a simulated convexity meningioma and filled out questionnaires to provide feedback on the experience. Performance metrics included volume of tissues removed, tool path lengths, duration of excessive forces applied and efficient use of the aspirator. Results were analyzed according to participants' level of training, gender, handedness, surgical experience in meningioma removal and hours/week playing musical instruments or video games. RESULTS: Seventy-two participants (10 medical students, 18 junior residents and 44 senior residents) were enrolled. Analyses demonstrated statistically significant increase in tumor removed and efficiency of ultrasonic aspirator use between medical students and residents, but not between junior and senior residents. After covariate adjustment for the number of meningioma cases operated on, multivariate analysis of the level of training became nonsignificant. Participants judged the exercise appropriate and realistic, desiring use of the system in current training programs. CONCLUSION: We have conducted a pilot validation study for the NeuroTouch tumor resection scenario and demonstrated for the first time, face, content and construct validity of a VR neurosurgical simulation exercise. Future full-scale studies will be conducted in noncompetitive settings and incorporate expert participants.

The development of a virtual simulator for training neurosurgeons to perform and perfect endoscopic endonasal transsphenoidal surgery.

BACKGROUND: A virtual reality (VR) neurosurgical simulator with haptic feedback may provide the best model for training and perfecting surgical techniques for transsphenoidal approaches to the sella turcica and cranial base. Currently there are 2 commercially available simulators: NeuroTouch (Cranio and Endo) developed by the National Research Council of Canada in collaboration with surgeons at teaching hospitals in Canada, and the Immersive Touch. Work in progress on other simulators at additional institutions is currently unpublished. OBJECTIVE: This article describes a newly developed application of the NeuroTouch simulator that facilitates the performance and assessment of technical skills for endoscopic endonasal transsphenoidal surgical procedures as well as plans for collecting metrics during its early use. METHODS: The main components of the NeuroTouch-Endo VR neurosurgical simulator are a stereovision system, bimanual haptic tool manipulators, and high-end computers. The software engine continues to evolve, allowing additional surgical tasks to be performed in the VR environment. Device utility for efficient practice and performance metrics continue to be developed by its originators in collaboration with neurosurgeons at several teaching hospitals in the United States. Training tasks are being developed for teaching 1- and 2-nostril endonasal transsphenoidal approaches. Practice sessions benefit from anatomic labeling of normal structures along the surgical approach and inclusion (for avoidance) of critical structures, such as the internal carotid arteries and optic nerves. CONCLUSION: The simulation software for NeuroTouch-Endo VR simulation of transsphenoidal surgery provides an opportunity for beta testing, validation, and evaluation of performance metrics for use in neurosurgical residency training. ABBREVIATIONS: CTA, cognitive task analysisVR, virtual reality.

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.

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.

Real-time control of angioplasty balloon inflation based on feedback from intravascular optical coherence tomography: preliminary study on an artery phantom.

A method is proposed to achieve computerized control of angioplasty balloon inflation, based on feedback from intravascular optical coherence tomography (IVOCT). Controlled balloon inflation could benefit clinical applications, cardiovascular research, and medical device industry. The proposed method was experimentally tested for balloon inflation within an artery phantom. During balloon inflation, luminal contour of the phantom was extracted from IVOCT images in real time. Luminal diameter was estimated from the obtained contour and was used in a feedback loop. Based on the estimated actual diameter and a target diameter, a computer controlled a programmable syringe pump to deliver or withdraw liquid in order to achieve the target diameter. The performance of the control method was investigated under different conditions, e.g., various flow rates and various target diameters. The results were satisfactory, as the control method provided convergence to the target diameters in various experiments.

Design and dynamic culture of 3D-scaffolds for cartilage tissue engineering.

Engineered scaffolds for tissue-engineering should be designed to match the stiffness and strength of healthy tissues while maintaining an interconnected pore network and a reasonable porosity. In this work, we have used 3D-plotting technique to produce poly-L-Lactide macroporous scaffolds with two different pore sizes. The ability of these macroporous scaffolds to support chondrocyte attachment and viability were compared under static and dynamic loading in vitro. Moreover, the 3D-plotting technique was combined with porogen-leaching, leading to macro/microporous scaffolds, so as to examine the effect of microporosity on the level of cell attachment and viability under similar loading condition. Canine chondrocytes' cells were seeded onto the scaffolds with different topologies, and the constructs were cultured for up to 2 weeks under static conditions or in a bioreactor under dynamic compressive strain of 10% strain, at a frequency of 1 Hz. The attachment and cell growth of chondrocytes were examined by scanning electron microscopy and by 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. A significant difference in cell attachment was observed in macroporous scaffolds with different pore sizes after 1, 7, and 14 days. Cell viability in the scaffolds was enhanced with decreasing pore size and increasing microporosity level throughout the culture period. Chondrocyte viability in the scaffolds cultured under dynamic loading was significantly higher (p<0.05) than the scaffolds cultured statically. Dynamic cell culture of the scaffolds improved cell viability and decreased the time of in vitro culture when compared to statically cultured constructs. Optimizing the culture conditions and scaffold properties could generate optimal tissue/constructs combination for cartilage repair.

Long-term in vitro human pancreatic islet culture using three-dimensional microfabricated scaffolds.

Human pancreatic islet in vitro culture is very challenging and requires the presence of various extra cellular matrix (ECM) components in a three-dimensional environment, which provides mechanical and biological support. The development of such an environment is vital in providing favourable conditions to preserve human islets in long-term culture. In this study, we investigated the effects of human islet culture within various three-dimensional environments; collagen I gel, collagen I gel supplemented with ECM components fibronectin and collagen IV, and microfabricated scaffold with ECM-supplemented gel. The cultured human islets were analyzed for functionality, gene expression and hormone content following long-term in vitro culture. It was clear the incorporation of ECM components within the three-dimensional support improved prolonged culture. However, long-term and highly uniform human islet culture within a microfabricated scaffold, with controlled pore structures, coupled with the presence of ECM components, displayed an insulin release profile similar to freshly isolated islets, yielding a stimulation index of approximately 1.8. Moreover, gene expression was markedly increased for all pancreatic genes, giving a approximately 50-fold elevation of insulin gene expression with respect to suspension culture. The distribution and presence of pancreatic hormones was also highly elevated. These findings provide a platform for the long-term maintenance and preservation of human pancreatic islets in vitro.

Bioengineering strategies to generate vascularized soft tissue grafts with sustained shape.

Tissue engineering offers the possibility for soft tissue reconstruction and augmentation without autologous grafting or conventional synthetic materials. Two critical challenges have been addressed in a number of recent studies: a biology challenge of angiogenesis and an engineering challenge of shape maintenance. These two challenges are inter-related and are effectively addressed by integrated bioengineering strategies. Recently, several integrated bioengineering strategies have been applied to improve bioengineered adipose tissue grafts, including internalized microchannels, delivery of angiogenic growth factors, tailored biomaterials and transplantation of precursor cells with continuing differentiation potential. Bioengineered soft tissue grafts are only clinically meaningful if they are vascularized, maintain shape and dimensions, and remodel with the host. Ongoing studies have begun to demonstrate the feasibility towards an ultimate goal to generate vascularized soft tissue grafts that maintain anatomically desirable shape and dimensions.

Design and fabrication of 3D porous scaffolds to facilitate cell-based gene therapy.

Biomaterials capable of efficient gene delivery by embedded cells provide a fundamental tool for the treatment of acquired or hereditary diseases. A major obstacle is maintaining adequate nutrient and oxygen diffusion to cells within the biomaterial. In this study, we combined the solid free-form fabrication and porogen leaching techniques to fabricate three-dimensional scaffolds, with bimodal pore size distribution, for cell-based gene delivery. The objective of this study was to design micro-/macroporous scaffolds to improve cell viability and drug delivery. Murine bone marrow-derived mesenchymal stromal cells (MSCs) genetically engineered to secrete erythropoietin (EPO) were seeded onto poly-L-lactide (PLLA) scaffolds with different microporosities. Over a period of 2 weeks in culture, an increase in cell proliferation and metabolic activity was observed with increasing scaffold microporosity. The concentration of EPO detected in supernatants also increased with increasing microporosity level. Our study shows that these constructs can promote cell viability and release of therapeutic proteins, and clearly demonstrates their capacity for a dual role as scaffolds for tissue regeneration and as delivery systems for soluble gene products.

In-vivo validation of a stent implantation numerical model.

A large deformation finite element model for the patient-specific prediction of stent implantation is presented as a potential tool to assist clinicians. The intervention simulation includes the complete stent deployment under balloon inflation and deflation in the artery. This paper describes the proposed model and presents an in-vivo validation of the model using pre- and post-intervention data from a patient who underwent stent implantation. Predicted cross-section areas at different artery positions are compared to post-intervention measurements. This work demonstrated the model's potential to become a relevant tool for predicting the arterial response to the intervention.

Computer prediction of balloon angioplasty from artery imaging.

The success of angioplasty 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 angioplasty is proposed as a potential tool to assist clinicians. This paper describes the general methodology and the algorithm that computes device/artery friction work during balloon insertion and deployment. The potential of the model is demonstrated with examples that include artery model reconstruction and prediction of friction on the arterial wall during balloon insertion and deployment.