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Virtual reality-based simulators are very helpful for trainees to acquire the skills of manipulating catheters and guidewires during the vascular interventional surgeries. In the development of such a simulator, however, it is a great challenge to realistically model and simulate deformable catheters and guidewires in an interactive manner. We prop...
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... this experiment, we tested the time performance of our method for the virtual catheters with different number of nodes when they advanced in a virtual tubular blood vessel. We show the results in Table 1. As shown in the table, it takes about 36 milliseconds to complete a calculation of our algorithm for a catheter with 200 nodes. ...
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The course and the success of an endovascular intervention can be influenced by the choice of the guide wire and primarily by its ability to access to the lesion. We propose a new approach for the mod-eling of guide wire.
Citations
... The validation methods presented in those studies are similar to the ones proposed in our work. Some studies have (visually) compared their results to in-vitro experiments of guiding catheters/guidewires in transfemoral and intracranial vessels (13)(17)(18) (16). Other studies have qualitatively and quantitatively compared their simulated and real wire positions by characterizing the local distances (14)(19) (20) and quantifying the curvature angles (25) of both the simulated and patient-specific guidewires through the abdominal aorta. ...
Background and objective:
Mechanical thrombectomy is a minimally invasive procedure that aims at removing the occluding thrombus from the vasculature of acute ischemic stroke patients. Thrombectomy success and failure can be studied using in-silico thrombectomy models. Such models require realistic modeling steps to be effective. We here present a new approach to model microcatheter tracking during thrombectomy.
Methods:
For 3 patient-specific vessel geometries, we performed finite-element simulations of the microcatheter tracking (1) following the vessel centerline (centerline method) and (2) as a one-step insertion simulation, where the microcatheter tip was advanced along the vessel centerline while its body was free to interact with the vessel wall (tip-dragging method). Qualitative validation of the two tracking methods was performed with the patient's digital subtraction angiography (DSA) images. In addition, we compared simulated thrombectomy outcomes (successful vs unsuccessful thrombus retrieval) and maximum principal stresses on the thrombus between the centerline and tip-dragging method.
Results:
Qualitative comparison with the DSA images showed that the tip-dragging method more realistically resembles the patient-specific microcatheter-tracking scenario, where the microcatheter approaches the vessel walls. Although the simulated thrombectomy outcomes were similar in terms of thrombus retrieval, the thrombus stress fields (and the associated fragmentation of the thrombus) were strongly different between the two methods, with local differences in the maximum principal stress curves up to 84%.
Conclusions:
Microcatheter positioning with respect to the vessel affects the stress fields of the thrombus during retrieval, and therefore, may influence thrombus fragmentation and retrieval in-silico thrombectomy.
... [29] FEA has been used widely in an attempt to simulate catheters and devices in the vascular system mainly for creation of physician training tools. [30][31][32] FEM has been described widely as a technique in relation to metal-based components in medical device literature. [ Zhang applied FEM to examining the relationship between braid angle and flexural kink resistance of braided composite interventional catheters. ...
Currently there are limited predictive modeling tools available for composite interventional catheter design. Most interventional catheter development involves iteration based design. Composite interventional catheters typically consist of a PTFE inner layer wrapped with a fine strand, metal reinforcement layer covered with a TPE (thermoplastic elastomer) outer layer. Fast reliable computational based techniques for early stage catheter design would limit the number of prototypes required to get to concept or design freeze stage therefore reducing development time. This paper’s goal is to examine how effective FEA is as a technique for predicting the performance of a composite catheter shaft. The steps taken and challenges overcome in creating a configurable FE model for a spirally reinforced composite catheter are outlined. The paper presents Finite Element (FE) generated data for tensile yield. This is a fundamental performance parameter in interventional catheter design. Catheters are designed to operate below their yield point. Models developed for simulating tensile yield can likely be adapted to simulate other performance characteristics such as flexural properties and torsion characteristics as part of future work. Data from FEA analysis is compared with data from physically testing catheters built to the same specification as that used in the FE model configuration.
... Dequidt et al. [13] and Wei et al. [14] then used this method to simulate embolization coils. Li et al. [15,16] proposed their FEM-based approach based on the principle of minimal total potential energy. Despite the numerical stability, the aforementioned FEM-based methods either had difficulties in simulating non-linear deformations or needed extra optimizations to achieve real-time performance. ...
Endovascular intervention is widely used in the treatment of cardiovascular and cerebrovascular diseases. This procedure requires physicians to be highly skilled at manipulating surgical devices such as catheters and guidewires. Virtual reality-based interventional simulators for surgical skills training have many advantages over traditional training methods. Simulation of the behavior of interventional devices is a very challenging task when developing such a simulator. In this paper, we proposed a shared centerline model incorporated with weighted material properties to represent the interventional devices. To efficiently and stably simulate the interactive behavior of these devices, we proposed an adaptive deviation-feedback approach to accelerate the convergence of the iterations. Additionally we proposed a track based control strategy to predict the behavior of the devices based on their past track to further decrease the amount of computation needed for the achievement of new equilibrium. The performance of our approach is experimentally validated via two endovascular interventional applications.
... Finite-element method (FEM) is a common numerical technique to model a deformable object, [47][48][49][50] including the behavior of the guidewire and catheter inside the body. 5,15,16,[20][21][22][24][25][26][27][28]31,32,34,37,39,41,[51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69] In this method, the instrument is first divided into a set of basic elements connected by nodes. A function that solves the equilibrium equations is found for each element. ...
... 5, 15, 22, 24-28, 37, 54-66, and 69, the instrument is considered as a rod-like structure, a long and thin circular structure with the length being much larger than the diameter. For rod modeling, there are different choices such as Euler-Bernoulli beam theory (deformation due to bending), Kirchhoff rod, 15,22,24,26,55 which is the geometrically nonlinear generalization of the Euler-Bernoulli beam theory, 70 Timoshenko beam theory (deformation due to bending and shear), and Cosserat rod, 25,27,28,58,61,[64][65][66]69 which is the geometrically nonlinear generalization of the Timoshenko beam theory. 70 In Refs. ...
... 70 In Refs. 15,22,37,41, and 61, the position of the instrument is expressed based on the principles of energy minimization. Thus, the energy function is expressed as (1) ...
Guidewires and catheters are used during minimally invasive interventional procedures to traverse in vascular system and access the desired position. Computer models are increasingly being used to predict the behavior of these instruments. This information can be used to choose the right instrument for each case and increase the success rate of the procedure. Moreover, a designer can test the performance of instruments before the manufacturing phase. A precise model of the instrument is also useful for a training simulator. Therefore, to identify the strengths and weaknesses of different approaches used to model guidewires and catheters, a literature review of the existing techniques has been performed. The literature search was carried out in Google Scholar and Web of Science and limited to English for the period 1960 to 2017. For a computer model to be used in practice, it should be sufficiently realistic and, for some applications, real time. Therefore, we compared different modeling techniques with regard to these requirements, and the purposes of these models are reviewed. Important factors that influence the interaction between the instruments and the vascular wall are discussed. Finally, different ways used to evaluate and validate the models are described. We classified the developed models based on their formulation into finite-element method (FEM), mass-spring model (MSM), and rigid multibody links. Despite its numerical stability, FEM requires a very high computational effort. On the other hand, MSM is faster but there is a risk of numerical instability. The rigid multibody links method has a simple structure and is easy to implement. However, as the length of the instrument is increased, the model becomes slower. For the level of realism of the simulation, friction and collision were incorporated as the most influential forces applied to the instrument during the propagation within a vascular system. To evaluate the accuracy, most of the studies compared the simulation results with the outcome of physical experiments on a variety of phantom models, and only a limited number of studies have done face validity. Although a subset of the validated models is considered to be sufficiently accurate for the specific task for which they were developed and, therefore, are already being used in practice, these models are still under an ongoing development for improvement. Realism and computation time are two important requirements in catheter and guidewire modeling; however, the reviewed studies made a trade-off depending on the purpose of their model. Moreover, due to the complexity of the interaction with the vascular system, some assumptions have been made regarding the properties of both instruments and vascular system. Some validation studies have been reported but without a consistent experimental methodology.
... The evaluating the array of colonoscopy simulators available, we identified some key aspects that have been developed that play significant roles in a high fidelity and realistic colonoscopy simulator. It is different from most previous methods [21][22][23]. ...
Background
Colonoscopy plays an important role in the clinical screening and management of colorectal cancer. The traditional ‘see one, do one, teach one’ training style for such invasive procedure is resource intensive and ineffective. Given that colonoscopy is difficult, and time-consuming to master, the use of virtual reality simulators to train gastroenterologists in colonoscopy operations offers a promising alternative. Methods
In this paper, a realistic and real-time interactive simulator for training colonoscopy procedure is presented, which can even include polypectomy simulation. Our approach models the colonoscopy as thick flexible elastic rods with different resolutions which are dynamically adaptive to the curvature of the colon. More material characteristics of this deformable material are integrated into our discrete model to realistically simulate the behavior of the colonoscope. Conclusion
We present a simulator for training colonoscopy procedure. In addition, we propose a set of key aspects of our simulator that give fast, high fidelity feedback to trainees. We also conducted an initial validation of this colonoscopic simulator to determine its clinical utility and efficacy.
... The buckling of a slender elastic body constrained by discrete or continuous walls is a problem widely encountered in engineering and medical applications. Examples include the constrained buckling of drill-pipes in deep drilling for oil and gas [1][2][3][4][5], the uplift buckling of a heavy elastic sheet from a one-sided rigid foundation in handling operations [6][7][8][9], and the insertion of a guide-wire or catheter into blood vessels [10][11][12][13]. There are actually two distinct classes of constrained buckling problems. ...
The paper proposes a method to analyze the post-buckling response of a planar elastica subjected to unilateral constraints. The method rests on assuming a deformed shape of the elastica that is consistent with an assumed buckling mode and given unilateral constraints, and on uniquely segmenting the elastica so that each segment is a particular realization of the same canonical problem. An asymptotic solution of the canonical problem, which is characterized by clamped–pinned boundary conditions, is derived using a perturbation technique. The complete solution of the constrained elastica is constructed by assembling the solution for each segment. It entails solving a nonlinear system of algebraic equations that embodies the continuity conditions between the segments and the contact constraints. The method is then applied to analyze the post-buckling response of a planar weightless elastica compressed inside two rigid frictionless horizontal walls. The length of the elastica could be either constant, or variable, but the focus of the analysis is on the response of a variable length elastica, which is gradually inserted inside the conduit. In the insertion problem, a configurational force is generated at the insertion point, which is not present in the classical problem of a constant length elastica (Bigoni et al., 2015). The proposed approach is shown to lead to a simple and accurate numerical technique to simulate the constrained buckling of an elastica. The optimal sequence of equilibrium configurations of the elastica associated with a monotonic force- or displacement-control loading is deduced in accordance with the principle of minimum energy.
... Alderliesten et al. [29,30] simulated rods, including friction, as a set of straight, non-bendable, incompressible beams with perfect torque control using a quasi-static approach. Later, Li et al. [31] improved this approach by using a FEM-based numerical solver. More recently, Duratti et al. [32] applied a solution closely resembling the CoRde model [17] to real-time interventional radiology simulation and [33,34] adapted the approach in [18] to simulate catheters and guidewires. ...
Purpose:
Effective and safe performance of cardiovascular interventions requires excellent catheter/guidewire manipulation skills. These skills are currently mainly gained through an apprenticeship on real patients, which may not be safe or cost-effective. Computer simulation offers an alternative for core skills training. However, replicating the physical behaviour of real instruments navigated through blood vessels is a challenging task.
Methods:
We have developed VCSim3-a virtual reality simulator for cardiovascular interventions. The simulator leverages an inextensible Cosserat rod to model virtual catheters and guidewires. Their mechanical properties were optimized with respect to their real counterparts scanned in a silicone phantom using X-ray CT imaging. The instruments are manipulated via a VSP haptic device. Supporting solutions such as fluoroscopic visualization, contrast flow propagation, cardiac motion, balloon inflation, and stent deployment, enable performing a complete angioplasty procedure.
Results:
We present detailed results of simulation accuracy of the virtual instruments, along with their computational performance. In addition, the results of a preliminary face and content validation study conveyed on a group of 17 interventional radiologists are given.
Conclusions:
VR simulation of cardiovascular procedure can contribute to surgical training and improve the educational experience without putting patients at risk, raising ethical issues or requiring expensive animal or cadaver facilities. VCSim3 is still a prototype, yet the initial results indicate that it provides promising foundations for further development.
... Clearly, the realism of the simulation environment is crucial as it determines the confidence one can attach to conducted analyses. Methods based on mass-spring models, 29, 30 finite elements 31 or discrete versions of the Elastic Kirchhoff Rod theory 32,33 have been proposed to simulate guidewire or catheter behaviour. CASCADE progresses the work by Konings et al. who predict the behaviour of a guidewire by minimizing the joint energy of guidewire and surrounding vessel. ...
Advances in miniaturized surgical instrumentation are key to less demanding and safer medical interventions. In cardiovascular procedures interventionalists turn towards catheter-based interventions, treating patients considered unfit for more invasive approaches. A positive outcome is not guaranteed. The risk for calcium dislodgement, tissue damage or even vessel rupture cannot be eliminated when instruments are maneuvered through fragile and diseased vessels. This paper reports on the progress made in terms of catheter design, vessel reconstruction, catheter shape modeling, surgical skill analysis, decision making and control. These efforts are geared towards the development of the necessary technology to autonomously steer catheters through the vasculature, a target of the EU-funded project Cognitive AutonomouS CAtheters operating in Dynamic Environments (CASCADE). Whereas autonomous placement of an aortic valve implant forms the ultimate and concrete goal, the technology of individual building blocks to reach such ambitious goal is expected to be much sooner impacting and assisting interventionalists in their daily clinical practice.
Introduction
l´apprentissage de la cardiologie interventionnelle basée sur la simulation (ABS) est un outil éducatif en plein essor dans le monde entier. Nous avons mené alors cette étude afin d´évaluer l´impact de l´ABS sur l´évolution des compétences des apprenants débutants dans le domaine, à travers un cycle de formation de faible durée.
Méthodes
nous avons mené une étude évaluative quasi-expérimentale de type avant-après dans le centre de simulation de la Faculté de Médecine de Sfax. Nous avons impliqué des résidents en cardiologie au début de leur formation en cardiologie interventionnelle. Tous les participants ont bénéficié d´un cycle de formation ayant duré 4 heures sur un simulateur à haute-fidélité de type Cathi®, après avoir donné leurs consentements. Le critère de jugement primaire a été définie par l´amélioration significative des scores de performance et de compétence avant et après le cycle. Le critère de jugement secondaire a été défini par la réduction de temps d´irradiation et le temps de la procédure.
Résultats
treize apprenants ont participé dans notre étude. Le score de performance s´est amélioré d´une médiane de 216,12% (ISQ= 285%). Cette amélioration était significativement plus nette chez les apprenants qui n´ont jamais eu accès à la salle de cathétérisme. Le score de performance a évolué d´une médiane de 31 (ISQ=40,5) à une médiane de 120 (ISQ=19,7), (p=0,001). Le score de compétence lié à la coronarographie s´est amélioré significativement, d´une médiane de 16 (ISQ=18) vers une médiane de 70 (ISQ=6), (p=0,001). Le score de compétence lié à l´angioplastie a évolué significativement d´une médiane de 10 (ISQ=17) vers une médiane de 50 (ISQ=13,7), p=0,001. Les durées de la coronarographie et de l´angioplastie ont été nettement réduites ayant évolué respectivement de 12 min (ISQ=2) à 7 min (ISQ=1) après le cycle de simulation (p=0,001), et d´une médiane de 19 min à une médiane de 17 min après la simulation, p= 0,002.
Conclusion
malgré la durée courte de la formation par simulation, notre étude Pilote a démontré une amélioration significative des compétences et performances des apprenants ainsi qu’un gain de temps de la réalisation des procédures et d´irradiation ce qui pourrait augmenter éventuellement le nombre de procédures réalisées quotidiennement dans notre cathlab et limiter l´irradiation du personnel et des patients tout en assurant une formation adéquate aux apprenants.
