Emerging personalized virtual brain models: next-generation resection neurosurgery for drug-resistant epilepsy?

Recently,a novel workflow known as the virtual epileptic patient(VEP)has been proposed by a research team from Aix Marseille Universitéin their papers published in Lancet Neurology,Science Translational Medicine and Epilepsia.This method involves creating an individualized virtual brain model based on computational modelling,which can facilitate clinical decision-making by estimating the epileptogenic zone and performing the virtual surgery.Here,we summarize brief workflow,strengths,and limitations of VEP,as well as its performance in a retrospective study of 53 patients with drug-resistant focal epilepsy who underwent stereoelectroencephalography.A large-scale clinical trial(NCT03643016)is underway to further assess VEP,which is expected to enroll 356 patients prospectively.As supporting evidence accumulates,the clinical application of VEP has the potential to improve clinical practice,leading to better outcomes and qualities of life of patients.

Interactive hepatic parenchymal transection simulation with haptic feedback

Background Liver resection involves surgical removal of a portion of the liver.It is used to treat liver tumors and liver injuries.The complexity and high-risk nature of this surgery prevents novice doctors from practicing it on real patients.Virtual surgery simulation was developed to simulate surgical procedures to enable medical professionals to be trained without requiring a patient,a cadaver,or an animal.Therefore,there is a strong need for the development of a liver resection surgery simulation system.We propose a real-time simulation system that provides realistic visual and tactile feedback for hepatic parenchymal transection.Methods The tetrahedron structure and cluster-based shape matching are used for physical model construction,topology update of a three-dimensional liver model soft deformation simulation,and haptic rendering acceleration.During the liver parenchyma separation simulation,a tetrahedral mesh is used for surface triangle subdivision and surface generation of the surgical wound.The shape-matching cluster is separated via component detection on an undirected graph constructed using the tetrahedral mesh.Results In our system,cluster-based shape matching is implemented on a GPU,whereas haptic rendering and topology updates are implemented on a CPU.Experimental results show that haptic rendering can be performed at a high frequency(>900Hz),whereas mesh skinning and graphics rendering can be performed at 45fps.The topology update can be executed at an interactive rate(>10Hz)on a single CPU thread.Conclusions We propose an interactive hepatic parenchymal transection simulation method based on a tetrahedral structure.The tetrahedral mesh simultaneously supports physical model construction,topology update,and haptic rendering acceleration.

Soft Tissue Deformation Model Based on Marquardt Algorithm and Enrichment Function

In order to solve the problem of high computing cost and low simulation accuracy caused by discontinuity of incision in traditional meshless model,this paper proposes a soft tissue deformation model based on the Marquardt algorithm and enrichment function.The model is based on the element-free Galerkin method,in which Kelvin viscoelastic model and adjustment function are integrated.Marquardt algorithm is applied to fit the relation between force and displacement caused by surface deformation,and the enrichment function is applied to deal with the discontinuity in the meshless method.To verify the validity of the model,the Sensable Phantom Omni force tactile interactive device is used to simulate the deformations of stomach and heart.Experimental results show that the proposed model improves the real-time performance and accuracy of soft tissue deformation simulation,which provides a new perspective for the application of the meshless method in virtual surgery.

A Three-Stage Cutting Simulation System Based on Mass-Spring Model

The cutting simulation of soft tissue is important in virtual surgery.It includes three major challenges in computation:Soft tissue simulation,collision detection,and handling,as well as soft tissue models.In order to address the earlier challenges,we propose a virtual cutting system based on the mass-spring model.In this system,MSM is utilized to simulate the soft tissue model.Residual stress is introduced to the model for simulating the shrinking effect of soft tissue in cutting.Second,a cylinder-based collision detection method is used to supervise the collision between surgical tools and soft tissue.Third,we simulate the cutting operation with a three-stage cutting method with swept volume,B´ezier curve,and an algorithm named shortest distance nodes matching method.In order to verify the system performance,we carry out three validation experiments on the proposed system:Cutting accuracy experiment,collision detection validation,and practical cutting evaluation.Experiments indicate that our system can well perform the shrinking effect of soft tissue in cutting.The system has fast and accurate collision detection.Moreover,the system can reconstruct smooth incisions vividly.

A Soft Tissue Acupuncture Model Based on Mass-Spring Force Ne

In the simulation of acupuncture manipulation,it is necessary to accurately capture the information of acupuncture points and particles around them.Therefore,a soft tissue modeling method that can accurately track model particles is needed.In this paper,a soft tissue acupuncture model based on the mass-spring force net is designed.MSM is used as the auxiliary model and the SHF model is combined.SHF is used to establish a three-layer soft tissue model of skin,fat,and muscle,and a layer of the MSM based force network is covered on the surface of soft tissue to realize the complementary advantages and disadvantages of spherical harmonic function and MSM.In addition,a springback algorithm is designed to simulate the springback phenomenon of soft tissue skin during acupuncture.The evaluation results show that the soft tissue acupuncture modeling method based on mass-spring force net can effectively simulate the springback phenomenon of soft tissue surface during acupuncture surgery,and has good comprehensive performance in the application of virtual acupuncture surgery simulation.

A Real-time Cutting Model Based on Finite Element and Order Reduction

Telemedicine plays an important role in Corona Virus Disease 2019(COVID-19).The virtual surgery simulation system,as a key component in telemedicine,requires to compute in real-time.Therefore,this paper proposes a realtime cutting model based on finite element and order reduction method,which improves the computational speed and ensure the real-time performance.The proposed model uses the finite element model to construct a deformation model of the virtual lung.Meanwhile,a model order reduction method combining proper orthogonal decomposition and Galerkin projection is employed to reduce the amount of deformation computation.In addition,the cutting path is formed according to the collision intersection position of the surgical instrument and the lesion area of the virtual lung.Then,the Bezier curve is adopted to draw the incision outline after the virtual lung has been cut.Finally,the simulation system is set up on the PHANTOM OMNI force haptic feedback device to realize the cutting simulation of the virtual lung.Experimental results show that the proposed model can enhance the real-time performance of telemedicine,reduce the complexity of the cutting simulation and make the incision smoother and more natural.

The application of virtual endoscopy with computed tomography in maxillofacial surgery

Objective To use virtual endoscopy to obtain detailed three-dimensional images of bone, soft tissue and paranasal sinus damage as well as images of adjacent unaffected areas for optimum surgical planning. Methods A spiral CT scanner was used to examine 46 cases of facial bone fractures, maxillary cysts, obstructive sleep apnea syndrome (OSAS) and maxillary bone tumours. Data were input into a navigator workstation to create images similar to those displayed by a fiberoptic endoscope. Various 3-D images were obtained when probe sites were changed.Results Virtual endoscopy can clearly display the anatomic structure of the paranasal sinuses, nasopharyngeal cavity and upper respiratory tract, revealing damage to the sinus wall caused by a bone tumor or fracture. In addition, the technique can be used to indicate volume changes of the upper respiratory tract in OSAS patients. These results were similar to those obtained through actual operations. Conclusions Virtual endoscopy is a new method which produces very clear images. It is reliable to provide detailed information for optimal operative planning.

Primary Clinical Research of a Patient Specific Implant System for an Old Zygomaticomaxillary Complex Comminuted Fracture

The objective of this study was to expound a novel surgical management technique assisted by patient-specific implants(PSIs)for comminuted fractures of the zygomaticomaxillary complex(ZMC).The aim of this study was to explore the feasibility of using PSIs to accurately restore and fix comminuted fractures.A male patient with an old ZMC comminuted fracture was used to describe the workflow,technique,and method.Computerassisted surgical simulation was used to determine the optimal plan for the reduction of bone segments prior to surgery.The PSIs were used to accurately guide the surgeon’s position of the bone segments,as planned,during the operation.Oral panoramic films and cephalometric films were taken immediately at 1,3,6,and 12 months after the operation,while computed tomography images of the whole skull were taken immediately,half a year,and one year after the operation.The patient’s follow-up showed that the zygomatic symmetry recovered well post-surgery and the patient was satisfied with the outcome.This new surgical method greatly improved the facial symmetry of this patient.

Real-Time Laparoscopic Cholecystectomy Simulation Using a Particle-Based Physical System

Laparoscopic cholecystectomy is used to treat cholecystitis and cholelithiasis.Because the high risk of the surgery prevents novice doctors from practicing it on real patients,VR-based surgical simulation has been developed to simulate surgical procedures to train surgeons without patients,cadavers,or animals.In this study,we propose a real-time system designed to provide plausible visual and tactile simulation of the main surgical procedures.To achieve this,the physical properties of organs are modeled by particles,and cluster-based shape matching is used to simulate soft deformation.The haptic interaction between tools and soft tissue is modeled as a collision between a capsule and particles.Constraint-based haptic rendering is used to generate feedback force and the non-penetrating position of the virtual tool.The proposed system can simulate the major steps of laparoscopic cholecystectomy,such as the anatomy of Calot’s triangle,clipping of the cystic duct and biliary artery,disjunction of the cystic duct and biliary artery,and separation of the gallbladder bed.The experimental results show that haptic rendering can be performed at a high frequency(>900 Hz),whereas mesh skinning and graphics rendering can be performed at 60 frames per second(fps).