Blood Flow Induced Physical Simulation Of Guidewire Shape For Virtual Vascular Intervention Training System In Real Time

Cardiovascular disease,with its increasing morbidity and mortality,has become one of the most dangerous threats to the health of human beings.It is widely treated with vascular intervention surgery,with its advantage of small incisions and quicker recovery.However,as the surgery is with complex procedures and demands for sufficient intervention skills,to cope with the increasing number of patients suffering from cardiovascular disease,It is becoming an urgent problem to train inexperienced surgeons master the skill efficiently.Virtual vascular intervention training system,which is a low cost,safe and effective solution,is able to provide an immersive virtual training environment for trainees.A decent guidewire behavior simulation is the key to the virtual vascular intervention system.Researchers have proposed abundant models on guidewire simulation such as geometric method and physically based model like mass-spring model,elastic rod model and FEM based model,etc.Although guidewire is clearly moving inside vessels fulfilled with blood flow,the influence of blood Flow has rarely been taken into consideration yet.In this paper,the blood influence is accounted in real time guidewire simulation model to improve physical fidelity.It is complicated to describe the physical model of blood flowing through complex vascular structures.This paper started from modeling the flow inside a regular smooth tube model with Poiseuille Law,which describes the relationship between the flow rate inside the tube and the pressure drop from entry to the exit of the tube.Then the vascular model was divided into a bunch of tubes based on its centerline data while the separate tubes were connected to approximate the original model.The discrete vascular model was represented abstractly as a directed graph with each node corresponding to the separating point along the centerline and each edge corresponding to a small tube vessel.The blood flow among complex vascular structures were computed by applying the Poiseuille Law in all the edges,meanwhile developing a set of linear equations according to the relationship of blood flow entering and leaving each node.The computed blood flow was then integrated into a former guidewire simulation model based on Kirchhoff Elastic Rod Model.The blood flow induced physical simulation model of guidewire was built by applying the flow force on all the mass points according to the position of each mass point inside the vessels located in real time during the simulation.The guidewire simulation was implemented with the C++ programming language,with a fine architecture based on the MVC model for potential requirements modification.The hardware acceleration technique was introduced into the implement with the Intel MKL library based on CPU for flow computation and the NVIDIA CUDA parallel computing architecture for physical computation of guidewire model.The proposed guidewire model takes blood flow influence into consideration and results an impressive difference comparing to the pure Kirchhoff Elastic Model with a major improvement in physical fidelity and received positive comments from cardiologists from clinics.Most of the existing guidewire simulation work evaluates their result from aspects of visual effects and time efficiency,while is lack of quantitative analysis.To better evaluate and test the proposed model,a same vascular model in reality was made with 3D printing technique and an electromagnetic tracking(EMT)system was applied for guidewire tracking.The quantitative analysis was performed by comparing the virtual track of simulated guidewire and real track recorded by EMT system.Experiments showed the result of proposed model got a same trend with the real track and the RMS value was low and stable.With the help of hardware acceleration,the simulation could run efficiently in real time with no compromise to physical fidelity improvement.The proposed guidewire simulation model with blood flow influence accounted makes an improvement on physical fidelity of simulation,which has its significance on helping inexperienced surgeons to master intervention skill quickly by providing more real training environment and shortening the training period.