Evaluating EPflex MRline Guidewire for Endovascular Interventions Guided by MRI at 3T vs. X-ray Fluoroscopy

This project sought to evaluate the efficacy of using the EPflex MRline guidewire for endovascular treatment guided by real-time Magnetic Resonance Imaging (MRI). MRI theoretically has numerous advantages over x-ray, the current clinical standard imaging modality for endovascular procedures. The most profound advantage of MRI is the ability to acquire physiological functional information, via perfusion and diffusion measures, for better intervention planning before and during the procedure. The EPflex guidewire was selectedbecause of its ability to perform in an MRI and x-ray fluoroscopy environment, allowing for relevant and useful comparisons of the guiding imaging modality. An abdominal aorta phantom was used to assess the ability of experienced and inexperienced operators to successfullynavigate the wire under each imaging modality. It was found that x-ray guidance provided statistically faster and more successful navigation attempts than MRI guidance; however, more clinical tests need to be performed in order to assess the clinical significance of these results.This study represents an important step in the direction of developing safer and more effective imaging systems for guiding endovascular procedures

Towards real-time cardiovascular magnetic resonance guided transarterial CoreValve implantation: in vivo evaluation in swine

<p>Abstract</p> <p>Background</p> <p>Real-time cardiovascular magnetic resonance (rtCMR) is considered attractive for guiding TAVI. Owing to an unlimited scan plane orientation and an unsurpassed soft-tissue contrast with simultaneous device visualization, rtCMR is presumed to allow safe device navigation and to offer optimal orientation for precise axial positioning. We sought to evaluate the preclinical feasibility of rtCMR-guided transarterial aortic valve implatation (TAVI) using the nitinol-based Medtronic CoreValve bioprosthesis.</p> <p>Methods</p> <p>rtCMR-guided transfemoral (n = 2) and transsubclavian (n = 6) TAVI was performed in 8 swine using the original CoreValve prosthesis and a modified, CMR-compatible delivery catheter without ferromagnetic components.</p> <p>Results</p> <p>rtCMR using TrueFISP sequences provided reliable imaging guidance during TAVI, which was successful in 6 swine. One transfemoral attempt failed due to unsuccessful aortic arch passage and one pericardial tamponade with subsequent death occurred as a result of ventricular perforation by the device tip due to an operating error, this complication being detected without delay by rtCMR. rtCMR allowed for a detailed, simultaneous visualization of the delivery system with the mounted stent-valve and the surrounding anatomy, resulting in improved visualization during navigation through the vasculature, passage of the aortic valve, and during placement and deployment of the stent-valve. Post-interventional success could be confirmed using ECG-triggered time-resolved cine-TrueFISP and flow-sensitive phase-contrast sequences. Intended valve position was confirmed by ex-vivo histology.</p> <p>Conclusions</p> <p>Our study shows that rtCMR-guided TAVI using the commercial CoreValve prosthesis in conjunction with a modified delivery system is feasible in swine, allowing improved procedural guidance including immediate detection of complications and direct functional assessment with reduction of radiation and omission of contrast media.</p

FROM CONCEPT, TO DESIGN, EVALUATION AND FIRST IN VIVO DEMONSTRATION OF A TELE-OPERATED CATHETER NAVIGATION SYSTEM

Percutaneous transluminal catheter (PTC) intervention is a medical technique used to assess and treat vascular and cardiac diseases, including electrophysiological conditions. A Interventional specialists use the vasculature as a passageway to guide the catheter to the site of interest, using fluoroscopic x-ray imaging for image-guidance. Common PTC procedures include: vascular angiography, inflating balloons and stents, depositing coils, and the treatment of cardiac arrhythmia via catheter ablation. Catheter ablation has gained prevalence over the last two decades, as the treatment success rate for atrial fibrillation reaches 100%. The close proximity between the interventionalist and the radiation source combined with the increased number of procedures performed annually has lead to increased lifetime exposure; escalating the interventionalist probability of developing cancer, cataracts or passing genetic defects to offspring. Furthermore, the lead garments that protect the interventionalist can lead to musculoskeletal injury. Both these factors have lead to increased occupational risk. Catheter navigation systems are commercially available to reduce these risks. Lack of intuitive design is a common failing among these systems. iii This thesis presents the design and validation of a remote catheter navigation system (RCNS) that utilizes dexterous skills of the interventionalist during remote navigation, by keeping the catheter in their hands of the interventionalist during remote navigation. For remote catheter manipulation, the interventionalist pushes, pulls, and twists an input catheter, which is placed inside an electromechanical sensor (CS). Position changes of the input catheter are transferred to a second electromechanical (CM) that replicates the sensed motion with a second, remote catheter. Design of this system begins with understanding the dynamic forces applied to the catheter during intravascular navigation. These dynamics were quantified and then used as operating parameters in the mechanical design of the CM. In a laboratory setting, motion sensed and replicated by the RCNS was found to be 1 mm in the axial direction, 1° in the radial direction, with a latency of 180 ms. In a multi-operator, comparative study using a specially constructed multi-path vessel phantom, comparable navigation efficacy was demonstrated between the RCNS and conventional catheter manipulation, with the RCNS requiring only 9s longer to complete the same tasks. Finally, remote navigation was performed in vivo to fully demonstrate the application of this system towards the diagnosis and treatment of cardiac arrhythmia

FROM CONCEPT, TO DESIGN, EVALUATION AND FIRST IN VIVO DEMONSTRATION OF A TELE-OPERATED CATHETER NAVIGATION SYSTEM

Percutaneous transluminal catheter (PTC) intervention is a medical technique used to assess and treat vascular and cardiac diseases, including electrophysiological conditions. Interventional specialists use the vasculature as a passageway to guide the catheter to the site of interest, using fluoroscopic x-ray imaging for image-guidance. Common PTC procedures include: vascular angiography, inflating balloons and stents, depositing coils, and the treatment of cardiac arrhythmia via catheter ablation. Catheter ablation has gained prevalence over the last two decades, as the treatment success rate for atrial fibrillation reaches 100%. The close proximity between the interventionalist and the radiation source combined with the increased number of procedures performed annually has lead to increased lifetime exposure; escalating the interventionalist probability of developing cancer, cataracts or passing genetic defects to offspring. Furthermore, the lead garments that protect the interventionalist can lead to musculoskeletal injury. Both these factors have lead to increased occupational risk. Catheter navigation systems are commercially available to reduce these risks. Lack of intuitive design is a common failing among these systems. iii This thesis presents the design and validation of a remote catheter navigation system (RCNS) that utilizes dexterous skills of the interventionalist during remote navigation, by keeping the catheter in their hands of the interventionalist during remote navigation. For remote catheter manipulation, the interventionalist pushes, pulls, and twists an input catheter, which is placed inside an electromechanical sensor (CS). Position changes of the input catheter are transferred to a second electromechanical (CM) that replicates the sensed motion with a second, remote catheter. Design of this system begins with understanding the dynamic forces applied to the catheter during intravascular navigation. These dynamics were quantified and then used as operating parameters in the mechanical design of the CM. In a laboratory setting, motion sensed and replicated by the RCNS was found to be 1 mm in the axial direction, 1° in the radial direction, with a latency of 180 ms. In a multi-operator, comparative study using a specially constructed multi-path vessel phantom, comparable navigation efficacy was demonstrated between the RCNS and conventional catheter manipulation, with the RCNS requiring only 9s longer to complete the same tasks. Finally, remote navigation was performed in vivo to fully demonstrate the application of this system towards the diagnosis and treatment of cardiac arrhythmia

Haptic Interface for the Simulation of Endovascular Interventions

Endovascular interventions are minimally invasive surgical procedures that are performed to diagnose and treat vascular diseases. These interventions use a combination of long and flexible instruments known as guidewire and catheter. A popular method of developing the skills required to manipulate the instruments successfully is through the use of virtual reality (VR) simulators. However, the interfaces of current VR simulators have several shortcomings due to limitations in the instrument tracking and haptic feedback systems design. A major challenge of developing physics-based training simulations of endovascular interventional procedures is to unobtrusively access the central, co-axial guidewire for tracking and haptics. This work sets out to explore the state of the art, to identify and develop novel solutions to this concentric occlusion problem, and to perform a validation of a proof of concept prototype. This multi port haptic interface prototype has been integrated with a 3-D virtual environment and features novel instrument tracking and haptic feedback actuation systems. The former involves the use of an optical sensor to detect guidewire movements through a clear catheter, whereas the latter utilises the placement of a customised electromagnetic actuator within the catheter hub. During the proof of concept validation process, both systems received positive reviews. Whilst the haptic interface prototype designed in this work has met the original objectives, there are still important aspects which need to be addressed to improve its content and face validity. With further development, the prototype has the potential to evolve and become a significant improvement over the haptic interfaces that exist today.Open Acces

Advanced cranial navigation

Neurosurgery is performed with extremely low margins of error. Surgical inaccuracy may have disastrous consequences. The overall aim of this thesis was to improve accuracy in cranial neurosurgical procedures by the application of new technical aids. Two technical methods were evaluated: augmented reality (AR) for surgical navigation (Papers I-II) and the optical technique of diffuse reflectance spectroscopy (DRS) for real-time tissue identification (Papers III-V). Minimally invasive skull-base endoscopy has several potential benefits compared to traditional craniotomy, but approaching the skull base through this route implies that at-risk organs and surgical targets are covered by bone and out of the surgeon’s direct line of sight. In Paper I, a new application for AR-navigated endoscopic skull-base surgery, based on an augmented-reality surgical navigation (ARSN) system, was developed. The accuracy of the system, defined by mean target registration error (TRE), was evaluated and found to be 0.55±0.24 mm, the lowest value reported error in the literature. As a first step toward the development of a cranial application for AR navigation, in Paper II this ARSN system was used to enable insertions of biopsy needles and external ventricular drainages (EVDs). The technical accuracy (i.e., deviation from the target or intended path) and efficacy (i.e., insertion time) were assessed on a 3D-printed realistic, anthropomorphic skull and brain phantom; Thirty cranial biopsies and 10 EVD insertions were performed. Accuracy for biopsy was 0.8±0.43 mm with a median insertion time of 149 (87-233) seconds, and for EVD accuracy was 2.9±0.8 mm at the tip with a median angular deviation of 0.7±0.5° and a median insertion time of 188 (135-400) seconds. Glial tumors grow diffusely in the brain, and patient survival is correlated with the extent of tumor removal. Tumor borders are often invisible. Resection beyond borders as defined by conventional methods may further improve a patient’s prognosis. In Paper III, DRS was evaluated for discrimination between glioma and normal brain tissue ex vivo. DRS spectra and histology were acquired from 22 tumor samples and 9 brain tissue samples retrieved from 30 patients. Sensitivity and specificity for the detection of low-grade gliomas were 82.0% and 82.7%, respectively, with an AUC of 0.91. Acute ischemic stroke caused by large vessel occlusion is treated with endovascular thrombectomy, but treatment failure can occur when clot composition and thrombectomy technique are mismatched. Intra-procedural knowledge of clot composition could guide the choice of treatment modality. In Paper IV, DRS, in vivo, was evaluated for intravascular clot characterization. Three types of clot analogs, red blood cell (RBC)-rich, fibrin-rich and mixed clots, were injected into the external carotids of a domestic pig. An intravascular DRS probe was used for in-situ measurements of clots, blood, and vessel walls, and the spectral data were analyzed. DRS could differentiate clot types, vessel walls, and blood in vivo (p<0,001). The sensitivity and specificity for detection were 73.8% and 98.8% for RBC clots, 100% and 100% for mixed clots, and 80.6% and 97.8% for fibrin clots, respectively. Paper V evaluated DRS for characterization of human clot composition ex vivo: 45 clot units were retrieved from 29 stroke patients and examined with DRS and histopathological evaluation. DRS parameters correlated with clot RBC fraction (R=81, p<0.001) and could be used for the classification of clot type with sensitivity and specificity rates for the detection of RBC-rich clots of 0.722 and 0.846, respectively. Applied in an intravascular probe, DRS may provide intra-procedural information on clot composition to improve endovascular thrombectomy efficiency

Artificial intelligence in the autonomous navigation of endovascular interventions: a systematic review

BackgroundAutonomous navigation of catheters and guidewires in endovascular interventional surgery can decrease operation times, improve decision-making during surgery, and reduce operator radiation exposure while increasing access to treatment.ObjectiveTo determine from recent literature, through a systematic review, the impact, challenges, and opportunities artificial intelligence (AI) has for the autonomous navigation of catheters and guidewires for endovascular interventions.MethodsPubMed and IEEEXplore databases were searched to identify reports of AI applied to autonomous navigation methods in endovascular interventional surgery. Eligibility criteria included studies investigating the use of AI in enabling the autonomous navigation of catheters/guidewires in endovascular interventions. Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA), articles were assessed using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). PROSPERO: CRD42023392259.ResultsFour hundred and sixty-two studies fulfilled the search criteria, of which 14 studies were included for analysis. Reinforcement learning (RL) (9/14, 64%) and learning from expert demonstration (7/14, 50%) were used as data-driven models for autonomous navigation. These studies evaluated models on physical phantoms (10/14, 71%) and in-silico (4/14, 29%) models. Experiments within or around the blood vessels of the heart were reported by the majority of studies (10/14, 71%), while non-anatomical vessel platforms “idealized” for simple navigation were used in three studies (3/14, 21%), and the porcine liver venous system in one study. We observed that risk of bias and poor generalizability were present across studies. No procedures were performed on patients in any of the studies reviewed. Moreover, all studies were limited due to the lack of patient selection criteria, reference standards, and reproducibility, which resulted in a low level of evidence for clinical translation.ConclusionDespite the potential benefits of AI applied to autonomous navigation of endovascular interventions, the field is in an experimental proof-of-concept stage, with a technology readiness level of 3. We highlight that reference standards with well-identified performance metrics are crucial to allow for comparisons of data-driven algorithms proposed in the years to come.Systematic review registrationidentifier: CRD42023392259

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