Image-guided Simulation of Heterogeneous Tissue Deformation For Augmented Reality during Hepatic Surgery

International audienceThis paper presents a method for real-time augmentation of vas- cular network and tumors during minimally invasive liver surgery. Internal structures computed from pre-operative CT scans can be overlaid onto the laparoscopic view for surgery guidance. Com- pared to state-of-the-art methods, our method uses a real-time biomechanical model to compute a volumetric displacement field from partial three-dimensional liver surface motion. This permits to properly handle the motion of internal structures even in the case of anisotropic or heterogeneous tissues, as it is the case for the liver and many anatomical structures. Real-time augmentation results are presented on in vivo and ex vivo data and illustrate the benefits of such an approach for minimally invasive surgery

Image-guided Simulation of Heterogeneous Tissue Deformation For Augmented Reality during Hepatic Surgery

International audienceThis paper presents a method for real-time augmentation of vas- cular network and tumors during minimally invasive liver surgery. Internal structures computed from pre-operative CT scans can be overlaid onto the laparoscopic view for surgery guidance. Com- pared to state-of-the-art methods, our method uses a real-time biomechanical model to compute a volumetric displacement field from partial three-dimensional liver surface motion. This permits to properly handle the motion of internal structures even in the case of anisotropic or heterogeneous tissues, as it is the case for the liver and many anatomical structures. Real-time augmentation results are presented on in vivo and ex vivo data and illustrate the benefits of such an approach for minimally invasive surgery

A Survey on the Current Status and Future Challenges Towards Objective Skills Assessment in Endovascular Surgery

Minimally-invasive endovascular interventions have evolved rapidly over the past decade, facilitated by breakthroughs in medical imaging and sensing, instrumentation and most recently robotics. Catheter based operations are potentially safer and applicable to a wider patient population due to the reduced comorbidity. As a result endovascular surgery has become the preferred treatment option for conditions previously treated with open surgery and as such the number of patients undergoing endovascular interventions is increasing every year. This fact coupled with a proclivity for reduced working hours, results in a requirement for efficient training and assessment of new surgeons, that deviates from the “see one, do one, teach one” model introduced by William Halsted, so that trainees obtain operational expertise in a shorter period. Developing more objective assessment tools based on quantitative metrics is now a recognised need in interventional training and this manuscript reports the current literature for endovascular skills assessment and the associated emerging technologies. A systematic search was performed on PubMed (MEDLINE), Google Scholar, IEEXplore and known journals using the keywords, “endovascular surgery”, “surgical skills”, “endovascular skills”, “surgical training endovascular” and “catheter skills”. Focusing explicitly on endovascular surgical skills, we group related works into three categories based on the metrics used; structured scales and checklists, simulation-based and motion-based metrics. This review highlights the key findings in each category and also provides suggestions for new research opportunities towards fully objective and automated surgical assessment solutions

VCSim3 - a VR Simulator for Cardiovascular Interventions

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

A Novel FEM-Based Numerical Solver for Interactive Catheter Simulation in Virtual Catheterization

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 propose a novel method to simulate the motion of catheters or guidewires and their interactions with patients' vascular system. Our method is based on the principle of minimal total potential energy. We formulate the total potential energy in the vascular interventional circumstance by summing up the elastic energy deriving from the bending of the catheters or guidewires, the potential energy due to the deformation of vessel walls, and the work by the external forces. We propose a novel FEM-based approach to simulate the deformation of catheters and guidewires. The motion of catheters or the guidewires and their responses to every input from the interventionalist can be calculated globally. Experiments have been conducted to validate the feasibility of the proposed method, and the results demonstrate that our method can realistically simulate the complex behaviors of catheters and guidewires in an interactive manner

Appareil et méthode facilitant la recanalisation des occlusions totales chroniques via la transmission d'ondes mécaniques dans un fil guide

Abstract : Peripheral Arterial Disease (PAD) and Coronary Heart Disease (CHD) a ects million of people over the world. Chronic Total Occlusions (CTO) are a prevalent and problematic condition in cardiovascular medicine. CTOs can be found in the lower extremities of patients with PAD, and in the coronary arteries of patients with CHD. CTOs are de ned as totally occluded arterial segments that have remained occluded for an extended period. This may cause angina in the case of a coronary CTO, or claudication possibly leading to limb amputation in the case of a peripheral CTO. The principal causes associated with the failure of a CTO angioplasty are the presence of calci cation, severe tortuosity, blunt proximal cap morphology, CTO length and prior failed attempt. The lack of a simple, e ective and safe angioplasty CTO crossing device has led to this research project. The main goal of this thesis was to design, develop and build a device to facilitate crossing of CTOs via the transmission of mechanical waves in a guidewire. The secondary goals were to evaluate the preliminary safety and e cacy of such device. The proposed CTO crossing system has two main components: (i) the shock wave generator (console) and (ii) the active guidewire. Inside the console generator, piezoelectric transducers are used to convert ampli ed electric signals into mechanical waves. These waves are further ampli ed as they are traveling in the parabolic re ector and dispersive waveguide. A connector is used to mechanically join the console generator with the active guidewire. The active guidewire design, construction and method of use are similar to conventional guidewire with the di erence that it can transmit mechanical waves. These mechanical waves create a micro-jackhammer e ect at the distal tip of the active guidewire and uid motion that are believed to enhance its crossing ability. In addition, the proposed CTO crossing system avoids heat accumulation at the tip of the active guidewire and can di erentiate tissues based on their elasticity. Di erent experiments were proposed to evaluate the preliminary safety and e cacy performance of the CTO crossing system. The safety pro le of the technology was evaluated by looking at the endothelial cell response when exposed to the active guidewire with mechanical energy delivery. An in-vivo study on healthy pigs was also used to evaluate the technical handling of the active guidewire. In addition, safety was assessed by looking at adverse events during the procedure and histology analysis of the treated arteries. E cacy was evaluated by measuring the output pressure in water near the distal tip of the active guidewire. Crossing ability was also assessed on the bench using surrogate materials and ex-vivo CTO specimens. Promising safety and e cacy results were demonstrated and motivated to continue the development of this unique technology.Les maladies vasculaires périphériques et coronariennes touchent des millions de personnes dans le monde. Les occlusions totales chroniques (CTO), qui représentent un blocage complet des artères, sont l'une des conséquences de ces maladies cardiovasculaires. Une CTO peut être observée dans les jambes et dans les artères coronaires. Une CTO située dans les coronaires peut causer l'angine de poitrine tandis qu'une CTO périphérique peut causer une claudication pouvant conduire jusqu'à une amputation du membre inférieur. Les principales causes menant à un échec d'une procédure de recanalisation percutanée d'une CTO sont la présence de calcification, une tortuosité sévère des artères, la présence d'un cap proximal convexe, la longueur de l'occlusion ainsi qu'un échec précédent. L'absence d'un appareil simple, efficace et sécuritaire pour la recanalisation percutanée d'une CTO a motivé les présents travaux de recherche. L'objectif principal des travaux de recherche présentés ici consiste à concevoir, développer et fabriquer un appareil facilitant la recanalisation des occlusions totales chroniques via la transmission d'ondes mécaniques dans un l guide. Les objectifs secondaires consistent à évaluer les résultats préliminaires liés à l'e cacité et la sécurité d'un tel appareil. L'appareil proposé a deux principales composantes : (i) le générateur d'ondes de choc (ou console) et (ii) le fil guide actif. La console utilise des transducteurs piézoélectriques pour convertir les signaux électriques des amplificateurs en ondes mécaniques. Ces ondes sont ensuite amplifiées en se propageant dans le ré ecteur parabolique et le guide dispersif. Un mécanisme de connexion est ajouté à la console pour faciliter la transmission des ondes mécaniques vers le fil guide actif. Le design et la construction du fil guide actif sont similaires à ceux des fils guides conventionnels. Les ondes mécaniques transmises le long du fil guide actif créent un effet marteau piqueur et un mouvement de fluide devant le fil qui favorisent ces performances. De plus, le système proposé ne génère aucune chaleur au bout du fil et a la capacité de différencier les tissus en fonction de leur élasticité. Plusieurs expériences ont été proposées afin d'évaluer les performances préliminaires de l'appareil de recanalisation. Le profil de sécurité de la technologie a été évalué en analysant la réponse des cellules de l'endothélium suite à une exposition au fil guide actif et à l'énergie des ondes mécaniques. Une étude animale sur des cochons sains a aussi été conduite a n d'évaluer les effets adverses associés à l'appareil et d'analyser les artères coronariennes traitées avec le fil guide actif. L'efficacité de l'appareil a été évaluée en mesurant la pression dans l'eau tout près du bout du fil guide actif. Des tests ont aussi été effectués afin d'évaluer les performances de recanalisation de l'appareil sur des matériaux analogues aux calcifications vasculaires et sur des vraies CTOs ex-vivo. Des résultats prometteurs ont été obtenus tant d'un point de vue de l'efficacité que de la sécurité de l'appareil

Constrained Stochastic State Estimation for 3D Shape Reconstruction of Catheters and Guidewires in Fluoroscopic Images

Minimally invasive fluoroscopy-based procedures are the gold standard for diagnosis and treatment of various pathologies of the cardiovascular system. This kind of procedures imply for the clinicians to infer the 3D shape of the device from 2D images, which is known to be an ill-posed problem. In this paper we present a method to reconstruct the 3D shape of the interventional device, with the aim of improving the navigation. The method combines a physics-based simulation with non-linear Bayesian filter. Whereas the physics-based model provides a prediction of the shape of the device navigating within the blood vessels (taking into account non-linear interactions between the catheter and the surrounding anatomy), an Unscented Kalman Filter is used to correct the navigation model using 2D image features as external observations. The proposed framework has been evaluated on both synthetic and real data, under different model parameterization, filter parameters tuning and external observations data-sets. Comparing the reconstructed 3D shape with a known ground truth, for the synthetic data-set, we obtained an average 3D Hausdorff distance of 0.07 ± 0.37 mm; the 3D distance at the tip equal to 0.021 ± 0.009 mm and the 3D mean distance at the distal segment of the catheter equal to 0.02 ± 0.008 mm. For the real data-set, the obtained average 3D Hausdorff Distance was of 0.95 ± 0.35 mm, the average 3D distance at the tip is equal to 0.7 ± 0.45 mm with an average 3D mean distance at the distal segment of 0.7 ± 0.46 mm. These results show the ability of our method to retrieve the 3D shape of the device, under a variety of filter parameterizations and challenging conditions: errors on the friction coefficient, ambiguous views and non-linear complex phenomena such as stick and slip motions

Microdispositivos:: herramientas para aplicaciones médicas

Abstract: This article reviews the literature on the latest advances in microdevices for medical applications. The objective is to show an overview of the latest devices and their applications, as well as future development vectors in the area. A search of about 170 articles was performed, most of them published between the years 2015 and 2021, of which 53 were chosen as they were the most topical and impactful in the research fields referred to drug delivery, minimally invasive surgery, and cranial and vascular intromissions. It is concluded that, although microdevices are at an advanced stage of research, they still have many challenges to be solved, which has not allowed clinical trials to be completed in many cases. One of the great challenges ahead is to increase the precision in locomotion and to make the devices capable of performing more complex tasks with the help of smaller-scale electronic devices.Resumen: El presente artículo realiza una revisión de la literatura sobre los últimos avances en cuanto a los micro dispositivos para aplicaciones médicas. El objetivo es mostrar un panorama general de los últimos dispositivos y sus aplicaciones, así como los futuros vectores de desarrollo en el área. Se realizó una búsqueda de alrededor de 170 artículos, la mayoría de ellos publicados entre los años 2015 y 2021, de los cuales se eligieron 53 al ser los de mayor actualidad e impacto en los campos de investigación referidos a la administración de fármacos, la cirugía mínimamente invasiva, y las intromisiones craneales y vasculares. Se concluye que, si bien los micro dispositivos están en una etapa avanzada de investigación, aún tienen muchos desafíos por solucionar, lo cual no ha permitido completar en muchos casos las pruebas clínicas. Uno de los grandes desafíos futuros es incrementar la precisión en locomoción y conseguir que los dispositivos puedan realizar tareas más complejas con ayuda de dispositivos electrónicos de menor escala

Impact of Soft Tissue Heterogeneity on Augmented Reality for Liver Surgery

International audienceThis paper presents a method for real-time augmented reality of internal liver structures during minimally invasive hepatic surgery. Vessels and tumors computed from pre-operative CT scans can be overlaid onto the laparoscopic view for surgery guidance. Compared to current methods, our method is able to locate the in-depth positions of the tumors based on partial three-dimensional liver tissue motion using a real-time biomechanical model. This model permits to properly handle the motion of internal structures even in the case of anisotropic or heterogeneous tissues, as it is the case for the liver and many anatomical structures. Experimentations conducted on phantom liver permits to measure the accuracy of the augmentation while real-time augmentation on in vivo human liver during real surgery shows the benefits of such an approach for minimally invasive surgery

Constrained Stochastic State Estimation of Deformable 1D Objects: Application to Single-view 3D Reconstruction of Catheters with Radio-opaque Markers

International audienceMinimally invasive fluoroscopy-based procedures are the gold standard for diagnosis and treatment of various pathologies of the cardiovascular system. This kind of procedures imply for the clinicians to infer the 3D shape of the device from 2D images, which is known to be an ill-posed 10 problem. In this paper we present a method to reconstruct the 3D shape of the interventional device, with the aim of improving the navigation. The method combines a physics-based simulation with non-linear Bayesian filter. Whereas the physics-based model provides a prediction of the shape of the device navigating within the blood vessels (taking into account non-linear interactions be-15 tween the catheter and the surrounding anatomy), an Unscented Kalman Filter is used to correct the navigation model using 2D image features as external observations. The proposed framework has been evaluated on both synthetic and real data, under different model parameterizations, filter parameters tuning and external observations data-sets. Comparing the reconstructed 3D shape with a known ground truth, for the synthetic data-set, we obtained average values for 3D Hausdorff Distance of $0.81 ± 0.53 mm$, for the 3D mean distance at the segment of $0.37 ± 0.17$ mm and an average 3D tip error of $0.24 ± 0.13 mm$. For the real data-set,we obtained an average 3D Hausdorff distance of $1.74 ± 0.77 mm$, a average 3D mean distance at the distal segment of 0.91 ± 0.14 mm, an average 3D error on the tip of $0.53 ± 0.09 mm$. These results show the ability of our method to retrieve the 3D shape of the device, under a variety of filter parameterizations and challenging conditions: uncertainties on model parameterization, ambiguous views and non-linear complex phenomena such as stick and slip motions