Current state in tracking and robotic navigation systems for application in endovascular aortic aneurysm repair

A Steerable and Electromagnetically Tracked Catheter: Navigation Performance Compared With Image Fusion in a Swine Model

PURPOSE

Cannulation of visceral vessels is necessary during fenestrated and branched endovascular aortic repair. In an attempt to reduce the associated radiation and contrast dose, an electromagnetically (EM) trackable and manually steerable catheter has been developed. The purpose of this preclinical swine study was to evaluate the cannulation performance and compare the cannulation performance using either EM tracking or image fusion as navigation tools.

MATERIALS AND METHODS

Both renal arteries, the superior mesenteric artery, and the celiac trunk were attempted to be cannulated using a 7F steerable, EM trackable catheter in 3 pigs. Seven operators attempted cannulation using first 3-dimensional (3D) image navigation with EM tracking and then conventional image fusion guidance. The rate of successful cannulation was recorded, as well as procedure time and radiation exposure. Due to the lack of an EM trackable guidewire, cannulations that required more than 1 attempt were attempted only with image fusion. The EM tracking position data were registered to preoperative 3D images using a vessel-based registration algorithm.

RESULTS

A total of 72 cannulations were attempted with both methods, and 79% (57) were successful on the first attempt for both techniques. There was no difference in cannulation rate (p=1), and time-use was similar. Successful cannulation with image fusion was achieved in 97% of cases when multiple attempts were allowed.

CONCLUSION

This study demonstrated the feasibility of a steerable and EM trackable catheter with 3D image navigation. Navigation performance with EM tracking was similar to image fusion, without statistically significant differences in cannulation rates and procedure times. Further studies are needed to demonstrate this utility in patients with aortic disease.

CLINICAL IMPACT

Electromagnetic tracking in combination with a novel steerable catheter reduces radiation and contrast media doses while providing three-dimensional visualization and agile navigation during endovascular aortic procedures.

Robotic applications for intracardiac and endovascular procedures

The large incisions and long recovery periods that accompany traditional cardiac surgery procedures along with the constant patient demand for minimally invasive procedures have motivated cardiac surgeons to implement the robotic technologies in their armamentarium. The robotic systems have been utilized successfully in various cardiac procedures including atrial septal defect repair, left atrial myxoma resection, MAZE procedure and left ventricular lead placement, yet coronary artery bypass and mitral valve repair still comprise the vast majority of them. This review analyzes the development of the robot-assisted cardiac surgery in recent years, its outcomes, advantages, disadvantages, its patient selection criteria as well as its economic feasibility. Robotic endovascular surgery, albeit its limited applications, is presently considered an attractive alternative to conventional endovascular approaches. The increased flexibility and precision along with the wider range of accessible anatomy provided by the endovascular robotic systems, have increased the pool of patients that can be offered minimally invasive treatment options and have helped to overcome many limitations of the traditional endovascular procedures. With this review we aimed to summarize the applications of the commercially available endovascular robotic devices, as well as the limitations and the future perspectives in the field of endovascular robotic surgery.

New tools to reduce radiation exposure during aortic endovascular procedures

INTRODUCTION

The evolution of endovascular surgery over the past 30 years has made it possible to treat increasingly complex vascular pathologies with an endovascular method. Although this generally speeds up the patient's recovery, the risks of health problems caused by long-term exposure to radioactive radiation increase. This warrants the demand for radiation-reducing tools to reduce radiation exposure during these procedures.

AREAS COVERED

For this systematic review Pubmed, Embase and Cochrane library databases were searched on 28 December 2021 to provide an overview of tools that are currently used or have the potential to contribute to reducing radiation exposure during endovascular aortic procedures. In addition, an overview is presented of radiation characteristics of clinical studies comparing a (potential) radiation-reducing device with conventional fluoroscopy use.

EXPERT OPINION

Radiation-reducing instruments such as fiber optic shape sensing or electromagnetic tracking devices offer the possibility to further reduce or even eliminate the use of radiation during endovascular procedures. In an era of increasing endovascular interventional complexity and awareness of the health risks of long-term radiation exposure, the use of these technologies could have a major impact on an ongoing challenge to move toward radiation-free endovascular surgery.

New paradigms in minimally-invasive vascular surgery

INTRODUCTION

Vascular surgery has been greatly evolved during the last decades and novel minimally invasive techniques have been introduced. Aim of this review is to briefly present all these advances and compare them with traditional repairs.

AREAS COVERED

The authors have extensively searched literature through the Pubmed and Embase databases. All articles published up to December 2021 referring to minimally invasive techniques used for treatment of peripheral artery disease, carotid disease, aortic aneurysms and venous disease were evaluated. Minimally invasive techniques under investigation included endovascular and hybrid techniques, robot-assisted and laparoscopic approaches.

EXPERT OPINION

Several minimally invasive techniques such as endovascular and hybrid approaches have been extensively used during the last two decades to treat vascular surgery patients offering them lower mortality and morbidity risks. Novel robot assisted techniques have shown promising results in preclinical studies although further clinical evaluation is needed.

Radiation-free Thoracic Endovascular Aneurysm Repair with Fiberoptic and Electromagnetic Guidance:A Phantom Study

PURPOSE

The purpose of this study was to evaluate the feasibility and accuracy of a radiation-free implantation of a thoracic aortic stent-graft employing fiberoptic and electromagnetic tracking in an anthropomorphic phantom.

MATERIALS AND METHODS

An anthropomorphic phantom was manufactured based on computed tomography angiography (CTA) data from a patient. An aortic stent-graft application system was equipped with a fiber Bragg gratings fiber and three electromagnetic sensors. The stent-graft was navigated in the phantom by three interventionalists using the tracking data generated by both technologies. One implantation procedure was performed. The technical success of the procedure was evaluated using digital subtraction angiography and pre- and post-interventional CTA. Tracking accuracy was determined at various anatomical landmarks based on separately acquired fluoroscopic images. The mean/maximum errors were measured for the stent-graft application system and the tip/end of the stent-graft.

RESULTS

The procedure resulted in technical success with a mean error below 3 mm for the entire application system and <2 mm for the position of the tip of the stent-graft. Navigation/implantation and handling of the device were rated sufficiently accurate and on a par with comparable, routinely used stent-graft application systems.

CONCLUSION

Our study demonstrates successful stent-graft implantation during a thoracic endovascular aortic repair procedure employing advanced guidance techniques and avoiding fluoroscopic imaging. This is an essential step in facilitating the implantation of stent-grafts and reducing the health risks associated with ionizing radiation during endovascular procedures.

Robotic endovascular surgery: current and future practice

Minimally invasive techniques have been at the forefront of surgical progress, and the evolution of endovascular robotic technologies has seen a paradigm shift in the focus of future innovation. Endovascular robotic technology may help overcome many of the challenges associated with traditional endovascular techniques by enabling greater control, stability, and precision of target navigation and treatment, while simultaneously reducing operator learning curves and improving safety. Several robotic systems have been developed to perform a broad range of endovascular procedures, but none have been used at scale or widely in routine practice, and the evidence for their safety, effectiveness, and efficiency remains limited. High cost and device complexity, lack of haptic feedback, and limited integration and interoperability with existing equipment and devices are the principal technology, cost, and sustainability barriers to the scalability and widespread adoption in day-to-day practice. In order to fully realize its potential, future robotic innovation must ensure compatibility with a range of off-the-shelf equipment that can be tracked and exchanged quickly during a procedure and come together with developments in navigation, tracking, and imaging. Reducing cost and complexity and supporting sustainability of the technology is key. In parallel, new technologies must be evaluated by clear and transparent standardized outcomes and be accompanied by robust clinical training. Key to the successful future development and dissemination of robotic technology is open collaboration among industry, clinicians, and patients in order to fully understand and address current challenges and enable the technology to realize its full potential.

Shape accuracy of fiber optic sensing for medical devices characterized in bench experiments

Purpose

Fiber Optic RealShape (FORS) is a new technology that visualizes the full three‐dimensional shape of medical devices, such as catheters and guidewires, using an optical fiber embedded in the device. This three‐dimensional shape provides guidance to clinicians during minimally invasive procedures, and enables intuitive navigation. The objective of this paper is to assess the accuracy of the FORS technology, as implemented in the current state‐of‐the‐art Philips FORS system. The FORS system provides the shape of the entire device, including tip location and orientation. We consider all three aspects.

Methods

In bench experiments, we determined the accuracy of the location and orientation of the tip by displacing and rotating the fiber end, while allowing the rest of the fiber to change shape freely. To test the accuracy of the full shape, we have placed the fiber in a groove, which was accurately machined in a thick, stiff metal “path plate.” We then compared the reconstructed shape with the known shape of the groove.

Results

The tip location is found with submillimeter accuracy, and the orientation is sensed with milliradian accuracy. The shape of a fiber in the path plate faithfully follows the known shape of the groove, with typical deviation less than 0.5 mm in the plane of the plate. Out of plane accuracy, perhaps slightly less relevant clinically, is more challenging, due to the influence of twist; yet even out of the plane, the deviation is only submillimeter.

Conclusion

The technology achieves submillimeter precision and provides full three‐dimensional shape, surpassing the reported precision of other navigation and tracking technologies, and therefore may potentially alleviate the need for fluoroscopy.

First in Human Clinical Feasibility Study of Endovascular Navigation with Fiber Optic RealShape (FORS) Technology

OBJECTIVE

Endovascular procedures are conventionally conducted using two dimensional fluoroscopy. A new technology platform, Fiber Optic RealShape (FORS), has recently been introduced allowing real time, three dimensional visualisation of endovascular devices using fiberoptic technology. It functions as an add on to conventional fluoroscopy and may facilitate endovascular procedures. This first in human study assessed the feasibility of FORS in clinical practice.

METHODS

A prospective cohort feasibility study was performed between July and December 2018. Patients undergoing (regular or complex) endovascular aortic repair (EVAR) or endovascular peripheral lesion repair (EVPLR) were recruited. FORS guidance was used exclusively during navigational tasks such as target vessel catheterisation or crossing of stenotic lesions. Three types of FORS enabled devices were available: a flexible guidewire, a Cobra-2 catheter, and a Berenstein catheter. Devices were chosen at the physician's discretion and could comprise any combination of FORS and non-FORS devices. The primary study endpoint was technical success of the navigational tasks using FORS enabled devices. Secondary study endpoints were user experience and fluoroscopy time.

RESULTS

The study enrolled 22 patients: 14 EVAR and eight EVPLR patients. Owing to a technical issue during start up, the FORS system could not be used in one EVAR. The remaining 21 procedures proceeded without device or technology related complications and involved 66 navigational tasks. In 60 tasks (90.9%), technical success was achieved using at least one FORS enabled device. Users rated FORS based image guidance "better than standard guidance" in 16 of 21 and "equal to standard guidance" in five of 21 procedures. Fluoroscopy time ranged from 0.0 to 52.2 min. Several tasks were completed without or with only minimal X-ray use.

CONCLUSION

Real time navigation using FORS technology is safe and feasible in abdominal and peripheral endovascular procedures. FORS has the potential to improve intra-operative image guidance. Comparative studies are needed to assess these benefits and potential radiation reduction.

Comparison of manual versus robot-assisted contralateral gate cannulation in patients undergoing endovascular aneurysm repair

PURPOSE

Robotic endovascular technology may offer advantages over conventional manual catheter techniques. Our aim was to compare the endovascular catheter path-length (PL) for robotic versus manual contralateral gate cannulation during endovascular aneurysm repair (EVAR), using video motion analysis (VMA).

METHODS

This was a multicentre retrospective cohort study with fluoroscopic video recordings of 24 EVAR cases (14 robotic, 10 manual) performed by experienced operators (> 50 procedures), obtained from four leading European centres. Groups were comparable with no statistically significant differences in aneurysm size (p = 0.47) or vessel tortuosity (p = 0.68). Two trained assessors used VMA to calculate the catheter PL during contralateral gate cannulation for robotic versus manual approaches.

RESULTS

There was a high degree of inter-observer reliability (Cronbach's α > 0.99) for VMA. Median robotic PL was 35.7 cm [interquartile range, IQR (30.8-51.0)] versus 74.1 cm [IQR (44.3-170.4)] for manual cannulation, p = 0.019. Robotic cases had a median cannulation time of 5.33 min [IQR (4.58-6.49)] versus 1.24 min [IQR (1.13-1.35)] in manual cases (p = 0.0083). Generated efficiency ratios (PL/aorto-iliac centrelines) was 1.6 (1.2-2.1) in robotic cases versus 2.6 (1.7-7.0) in manual, p = 0.031.

CONCLUSION

Robot-assisted contralateral gate cannulation in EVAR leads to decreased navigation path lengths and increased economy of movement compared with manual catheter techniques. The benefit could be maximised by prioritising robotic catheter shaping over habituated reliance on guidewire manipulation. Robotic technology has the potential to reduce the endovascular footprint during manipulations even for experienced operators with the added advantage of zero radiation exposure.

[Artificial intelligence in vascular surgery and vascular medicine]

New digital technologies will also gain in importance in vascular surgery. There is a wide field of potential applications. Simulation-based training of endovascular procedures can lead to improvement in procedure-specific parameters and reduce fluoroscopy and procedural times. The use of intraoperative image-guided navigation and robotics also enables a reduction of the radiation dose. Artificial intelligence can be used for risk stratification and individualization of treatment approaches. Health apps can be used to improve the follow-up care of patients.

Vessel-based rigid registration for endovascular therapy of the abdominal aorta

BACKGROUND

Combining electromagnetic tracking of instruments with preoperatively acquired images can provide detailed visualization for intraoperative guidance and reduce the need for fluoroscopy and contrast. In this study, we investigated the accuracy of a vessel-based registration method designed for matching preoperative image and electromagnetically tracked positions for endovascular therapy.

MATERIAL AND METHODS

An open-source registration method was used to match the centerline extracted from computed tomography (CT) to electromagnetically tracked positions within a vascular phantom representing the abdominal aorta with bifurcations. The target registration error (TRE) was calculated for 11 fiducials distributed over the phantom. Median and intra-quartile range (IQR) for 30 registrations was reported. TRE < 5 mm was claimed sufficient for endovascular navigation, evaluated using the Wilcoxon signed-rank test. TRE was also compared to a 3D-3D registration method based on intraoperative cone-beam CT, using the Mann-Whitney U-test.

RESULTS

The TRE was 3.75 (IQR: 3.48-3.99) mm for the centerline registration algorithm and 3.21 (IQR: 1.50-3.57) mm for the 3D-3D method (p < .001). For both methods, the TRE was significantly < 5 mm (p < .001).

CONCLUSION

The centerline registration method was feasible, with an accuracy sufficient for navigation in endovascular therapy. The centerline method avoids additional image acquisition for registration purpose only.

Total Variation Regularization of Pose Signals with an Application to 3D Freehand Ultrasound

Three-dimensional freehand imaging techniques are gaining wider adoption due to their ?exibility and cost ef?ciency. Typical examples for such a combination of a tracking system with an imaging device are freehand SPECT or freehand 3D ultrasound. However, the quality of the resulting image data is heavily dependent on the skill of the human operator and on the level of noise of the tracking data. The latter aspect can introduce blur or strong artifacts, which can signi?cantly hamper the interpretation of image data. Unfortunately, the most commonly used tracking systems to date, i.e. optical and electromagnetic, present a trade-off between invading the surgeon's workspace (due to line-of-sight requirements) and higher levels of noise and sensitivity due to the interference of surrounding metallic objects. In this work, we propose a novel approach for total variation regularization of data from tracking systems (which we term pose signals) based on a variational formulation in the manifold of Euclidean transformations. The performance of the proposed approach was evaluated using synthetic data as well as real ultrasound sweeps executed on both a Lego phantom and human anatomy, showing signi?cant improvement in terms of tracking data quality and compounded ultrasound images. Source code can be found at https://github.com/IFL-CAMP/pose_regularization.

Manually Steerable Catheter With Improved Agility

Purpose

A prototype steerable catheter was designed for endovascular procedures. This technical pilot study reports the initial experience using the catheter for cannulation of visceral arteries.

Technique

The 7F catheter was manually steerable with operator control handle for bending and rotation of the tip. The maximum bending angle was approximately 90° and full 360° rotation of the tip was supported. The study involved 1 pig with 4 designated target arteries: the left and right renal arteries, the superior mesenteric artery, and the celiac trunk. Fluoroscopy with 3-dimensional (3D) overlay showing the ostia from preoperative computed tomography angiography was used for image guidance. The cannulation was considered successful if the guidewire was placed well inside the target artery. In addition to evaluating cannulation success, procedure time and associated radiation doses were recorded. The procedure was performed twice with 2 different operators.

Conclusions

Both operators successfully reached all 4 target arteries, demonstrating the feasibility of the steerable catheter for endovascular cannulation of visceral arteries. No contrast medium was used, and median radiation dose was 4.5 mGy per cannulation. An average of approximately 2 minutes was used per cannulation. This study motivates further testing in a more comprehensive study to evaluate reproducibility in several animals and with inclusion of more operators. Further development by integrating the new catheter tool in a navigation system is also an interesting next step, combining fine control of catheter tip movements and 3D image guidance without ionizing radiation.

Design and Experimental Validation of an Active Catheter for Endovascular Navigation

Endovascular techniques have many advantages but rely strongly on operator skills and experience. Robotically steerable catheters have been developed but few are clinically available. We describe here the development of an active and efficient catheter based on shape memory alloys (SMA) actuators. We first established the specifications of our device considering anatomical constraints. We then present a new method for building active SMA-based catheters. The proposed method relies on the use of a core body made of three parallel metallic beams and integrates wire-shaped SMA actuators. The complete device is encapsulated into a standard 6F catheter for safety purposes. A trial-and-error campaign comparing 70 different prototypes was conducted to determine the best dimensions of the core structure and of the SMA actuators with respect to the imposed specifications. The final prototype was tested on a silicon-based arterial model and on a 23 kg pig. During these experiments, we were able to cannulate the supra-aortic trunks and the renal arteries with different angulations and without any complication. A second major contribution of this paper is the derivation of a reliable mathematical model for predicting the bending angle of our active catheters. We first use this model to state some general qualitative rules useful for an iterative dimensional optimization. We then perform a quantitative comparison between the actual and the predicted bending angles for a set of 13 different prototypes. The relative error is less than 20% for bending angles between 100 deg and 150 deg, which is the interval of interest for our applications.

ROS-IGTL-Bridge: an open network interface for image-guided therapy using the ROS environment

PURPOSE

With the growing interest in advanced image-guidance for surgical robot systems, rapid integration and testing of robotic devices and medical image computing software are becoming essential in the research and development. Maximizing the use of existing engineering resources built on widely accepted platforms in different fields, such as robot operating system (ROS) in robotics and 3D Slicer in medical image computing could simplify these tasks. We propose a new open network bridge interface integrated in ROS to ensure seamless cross-platform data sharing.

METHODS

A ROS node named ROS-IGTL-Bridge was implemented. It establishes a TCP/IP network connection between the ROS environment and external medical image computing software using the OpenIGTLink protocol. The node exports ROS messages to the external software over the network and vice versa simultaneously, allowing seamless and transparent data sharing between the ROS-based devices and the medical image computing platforms.

RESULTS

Performance tests demonstrated that the bridge could stream transforms, strings, points, and images at 30 fps in both directions successfully. The data transfer latency was <1.2 ms for transforms, strings and points, and 25.2 ms for color VGA images. A separate test also demonstrated that the bridge could achieve 900 fps for transforms. Additionally, the bridge was demonstrated in two representative systems: a mock image-guided surgical robot setup consisting of 3D slicer, and Lego Mindstorms with ROS as a prototyping and educational platform for IGT research; and the smart tissue autonomous robot surgical setup with 3D Slicer.

CONCLUSION

The study demonstrated that the bridge enabled cross-platform data sharing between ROS and medical image computing software. This will allow rapid and seamless integration of advanced image-based planning/navigation offered by the medical image computing software such as 3D Slicer into ROS-based surgical robot systems.

Flexible robotics with electromagnetic tracking improves safety and efficiency during in vitro endovascular navigation

OBJECTIVE

One limitation of the use of robotic catheters is the lack of real-time three-dimensional (3D) localization and position updating: they are still navigated based on two-dimensional (2D) X-ray fluoroscopic projection images. Our goal was to evaluate whether incorporating an electromagnetic (EM) sensor on a robotic catheter tip could improve endovascular navigation.

METHODS

Six users were tasked to navigate using a robotic catheter with incorporated EM sensors in an aortic aneurysm phantom. All users cannulated two anatomic targets (left renal artery and posterior "gate") using four visualization modes: (1) standard fluoroscopy mode (control), (2) 2D fluoroscopy mode showing real-time virtual catheter orientation from EM tracking, (3) 3D model of the phantom with anteroposterior and endoluminal view, and (4) 3D model with anteroposterior and lateral view. Standard X-ray fluoroscopy was always available. Cannulation and fluoroscopy times were noted for every mode. 3D positions of the EM tip sensor were recorded at 4 Hz to establish kinematic metrics.

RESULTS

The EM sensor-incorporated catheter navigated as expected according to all users. The success rate for cannulation was 100%. For the posterior gate target, mean cannulation times in minutes:seconds were 8:12, 4:19, 4:29, and 3:09, respectively, for modes 1, 2, 3 and 4 (P = .013), and mean fluoroscopy times were 274, 20, 29, and 2 seconds, respectively (P = .001). 3D path lengths, spectral arc length, root mean dimensionless jerk, and number of submovements were significantly improved when EM tracking was used (P < .05), showing higher quality of catheter movement with EM navigation.

CONCLUSIONS

The EM tracked robotic catheter allowed better real-time 3D orientation, facilitating navigation, with a reduction in cannulation and fluoroscopy times and improvement of motion consistency and efficiency.

Endovascular treatment of complex aortic aneurysms: prevalence of acute kidney injury and effect on long-term renal function

Objectives

To analyse predictors for short- and long-term renal function changes after fenestrated and branched endovascular aortic repair (EVAR).

Methods

A total of 157 patients underwent fenestrated and branched EVAR. Procedural intra-arterial iodinated contrast volume was documented. Serum creatinine and estimated glomerular filtration rate (eGFR) at baseline, during 48 h following EVAR, at discharge and latest moment of follow-up were recorded. Development of post-EVAR acute kidney injury (AKI; according to AKIN criteria), and potential risk factors for renal failure were recorded. Multivariate regression analyses were used to identify independent risk factors for AKI and eGFR decrease during follow-up.

Results

Forty-three patients (28 %) developed post-EVAR AKI. Long procedure time and occlusion of accessory renal arteries were independent risk factors for development of AKI. (odds ratio (OR) 1.005 per minute, 95 % CI 1.001–1.01; p = 0.025 and OR 3.02, 95 % CI 1.19–8.16; p = 0.029). Post-EVAR AKI was associated with a significantly increased risk for eGFR decrease at discharge and latest follow-up (hazard ratio (HR) 3.47, 95 % CI 1.63–7.36, p = 0.001 and HR 3.01, 95 % CI 1.56–5.80; p = 0.001). Iodinated contrast volume was not an independent risk factor for AKI or eGFR decrease during follow-up.

Conclusion

Development of post-EVAR AKI is an independent risk factor for long-term renal function decrease.

Key Points

• Longer procedure time is associated with an increased risk for AKI.

• Renal perfusion defects on angiography are associated with increased risk for AKI.

• Post-EVAR AKI is associated with higher probability for long-term eGFR decrease.

• Iodinated contrast volume is not an independent risk factor for AKI.

• Iodinated contrast volume is not an independent risk factor for long-term eGFR decrease.