Side-branched AAA stent graft insertion using navigation technology: a phantom study

Mixed Reality in der Gefäßchirurgie – ein Scoping Review

Hintergrund „Mixed Reality“ (MR) erlaubt die Projektion von virtuellen Objekten in das Sichtfeld des Anwenders durch ein Head-mounted Display (HMD). Im gefäßchirurgischen Behandlungsspektrum könnten MR-Anwendungen in Zukunft einen Nutzen darstellen. Im folgenden Scoping Review soll eine Orientierung über die aktuelle Anwendung der genannten Technologien im Bereich der Gefäßchirurgie gegeben und Forschungsziele für die Zukunft definiert werden. Material und Methoden Es erfolgte eine systematische Literaturrecherche in PubMed (MEDLINE) mit den Suchbegriffen „aorta“, „intervention“, „endovsacular intervention“, „vascular surgery“, „aneurysm“, „endovascular“, „vascular access“ jeweils in Kombination mit „mixed reality“ oder „augmented reality“. Die Suche erfolgte nach PRISMA-Leitlinie (Preferred Reporting Items for Systematic reviews and Meta-Analyses) für Scoping Reviews. Ergebnisse Aus 547 Literaturstellen konnten 8 relevante Studien identifiziert werden. Die Suchergebnisse konnten in 2 Anwendungskategorien eingeteilt werden: (1) MR mit dem Ziel des Informationsmanagements und zur Verbesserung der periprozeduralen Ergonomie gefäßchirurgischer Eingriffe (n = 3) sowie (2) MR mit dem Ziel der intraoperativen Navigation bei gefäßchirurgischen Eingriffen (n = 5). Die Registrierung des physischen Patienten mit dem virtuellen Objekt und das Tracking von Instrumenten in der MR-Umgebung zur intraoperativen Navigation ist dabei im Fokus des wissenschaftlichen Interesses und konnte technisch erfolgreich am Phantom- und Tiermodell gezeigt werden. Die bisher vorgestellten Methoden sind jedoch mit hohem infrastrukturellem Aufwand und relevanten Limitationen verbunden. Schlussfolgerung Der Einsatz von MR im Bereich der Gefäßchirurgie ist grundsätzlich vielversprechend. Für die Zukunft sollten alternative, pragmatische Registrierungsmethoden mit entsprechender Quantifizierung des Positionierungsfehlers angestrebt werden. Die entwickelten Soft- und Hardwarelösungen sollten auf das Anforderungsprofil der Gefäßchirurgie angepasst werden. Das elektromagnetische Instrumenten-Tracking erscheint als sinnvolle, komplementäre Technologie zur Umsetzung der MR-assistierten Navigation.

Updates in Endovascular Procedural Navigation In Canadian Journal of Cardiology

There have been significant advancements in endovascular technology over the past decade. Increasingly complex disease processes are being addressed in a less invasive fashion, while still relying on standard two-dimensional, gray-scale fluoroscopy imaging to guide the procedures. With the advent of flat panel detectors as standard on fluoroscopy units and the utilization of fluoroscopy cone-beam computed tomography, the development of improved imaging tools has occurred which will help improve the imaging modalities used to perform these endovascular procedures. . Fusion imaging, the overlay of pre-operative 3-dimensional computed tomography images helps interventionalists perform endovascular procedures. Building on this technology, improvements in its function and utilization have occurred with the additional application of artificial intelligence and machine learning - allowing the images to independently accommodate to changes in the visualized anatomy. Corresponding development of navigation systems, allowing for the tracking of endovascular tools within these images using either fiberoptics of electromagnetic field generators, are looking to improve the accuracy of the procedures while reducing the need for radiation and contrast agents. These tools are making a dramatic change in our ability to perform complex endovascular procedures, and are the future gold standard. Ultimately, these will allow procedures to occur more quickly and more safely.

Endovascular treatment of thoracoabdominal aortic aneurysms

Endovascular repair of thoracoabdominal aneurysms using fenestrated and/or branched stent grafts is technically feasible and efficacious but carries a steep learning curve. This innovative surgical approach is associated with less perioperative morbidity than traditional open repair and its early and mid-term outcomes are very favorable. Spinal cord ischemia remains a devastating complication after these procedures, hence the importance of various neuroprotective strategies. Widespread applicability remains limited in the United States, as no custom-made or off-the-shelf endografts are commercially available. Access to these devices remains limited to physician-sponsored or industry-sponsored clinical trials, but results from the Cook p-Branch and Gore Thoracoabdominal Branch Endoprosthesis trials are on the horizon.

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.

Three-Dimensional Holographic Guidance, Navigation, and Control (3D-GNC) for Endograft Positioning in Porcine Aorta: Feasibility Comparison With 2-Dimensional X-Ray Fluoroscopy

OBJECTIVES

Intraprocedural deployment of endovascular devices during complex aortic repair with 2-dimensional (2D) x-ray fluoroscopic guidance poses challenges in terms of accurate delivery system positioning and increased risk of x-ray radiation exposure with prolonged fluoroscopy times, particularly in unfavorable anatomy. The objective of this study was to assess feasibility of using an augmented reality (AR) system to position and orient a modified aortic endograft delivery system in comparison with standard fluoroscopy.

MATERIALS AND METHODS

The 3-dimensional guidance, navigation, and control (3D-GNC) prototype system was developed for eventual integration with the Intra-Operative Positioning System (IOPS, Centerline Biomedical, Cleveland, OH) to project spatially registered 3D holographic representations of the subject-specific aorta for intraoperative guidance and coupled with an electromagnetically (EM) tracked delivery system for intravascular navigation. Numerical feedback for controlling the endograft landing zone distance and ostial alignment was holographically projected on the operative field. Visualization of the holograms was provided via a commercially available AR headset. A Zenith Spiral-Z AAA limb stent-graft was modified with a scallop, 6 degree-of-freedom EM sensor for tracking, and radiopaque markers for fluoroscopic visualization. In vivo, 10 interventionalists independently positioned and oriented the delivery system to the ostia of renal or visceral branch vessels in anesthetized swine via open femoral artery access using 3D-GNC and standard fluoroscopic guidance. Procedure time, fluoroscopy time, cumulative air kerma, and contrast material volume were recorded for each technique. Positioning and orientation accuracy was determined by measuring the target landing-zone distance error (δ_LZE) and the scallop-ostium angular alignment error (θ_SOE) using contrast-enhanced cone beam computed tomography imaging after each positioning for each technique. Mean, standard deviation, and standard error are reported for the performance variables, and Student's t tests were used to evaluate statistically significant differences in performance mean values of 3D-GNC and fluoroscopy.

RESULTS

Technical success for the use of 3D-GNC to orient and position the endovascular device at each renal-visceral branch ostium was 100%. 3D-GNC resulted in 56% decrease in procedure time in comparison with standard fluoroscopic guidance (p<0.001). The 3D-GNC system was used without fluoroscopy or contrast-dye administration. Positioning accuracy was comparable for both techniques (p=0.86), while overall orientation accuracy was improved with the 3D-GNC system by 41.5% (p=0.008).

CONCLUSIONS

The holographic 3D-GNC system demonstrated improved accuracy of aortic stent-graft positioning with significant reductions in fluoroscopy time, contrast-dye administration, and procedure time.

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

OBJECTIVE

This study reviewed the current developments in manual tracking and robotic navigation technologies for application in endovascular aortic aneurysm repair (EVAR).

METHODS

EMBASE and MEDLINE databases were searched for studies reporting manual tracking or robotic navigation systems that are able to manipulate endovascular surgical tools during abdominal or thoracic aortic aneurysm repair. Reports were grouped by the navigation systems and categorized into phantom, animal, and clinical studies. First, the general characteristics of each system were compared. Second, target registration error and deployment error were used to compare the accuracy of the tracking systems. Third, all systems were reviewed for fluoroscopy time (FT), radiation dose, and contrast volumes, if reported, in rigid and nonrigid studies. Fourth, vascular cannulation performance of the systems was compared, studying cannulation time, Imperial College Complex Cannulation Scoring Tool score, and the number of wall hits and catheter movements within rigid studies.

RESULTS

Of 721 articles and references found, 18 studies of four different navigation systems were included: the Aurora (Northern Digital, Waterloo, Ontario, Canada) tracking system, the StealthStation (Medtronic Inc, Minneapolis, Minn) tracking system, an ultrasound localization tracking system, and the Sensei (Hansen Medical, Mountain View, Calif) steerable remote-controlled robotic navigation system. The mean tracking accuracy averaged 1 mm for the three manual tracking systems measured in a rigid environment. An increase of target registration error reaching >3 mm was reported when measured in a nonrigid experimental environment or due to external distortion factors. Except within small-animal studies or case studies, no evidence was found on reduction of clinical outcome parameters, such as FT, radiation dose, and contrast volumes, within clinical EVAR. A comparison of vascular cannulation performance in rigid studies revealed that the Sensei robotic system might have an advantage during advanced cannulation compared with standard cannulation within complex cannulations tasks.

CONCLUSIONS

This review summarizes the current studies on manual tracking and robotic navigation systems for application in EVAR. The main focus of these systems is improving aortic vessel cannulation, required in complex EVAR, in which the robotic system with the improved steerability is favored over manual tracking systems or conventional cannulation. All reviewed tracking systems still require X-ray for anatomic imaging, stent graft deployment, and device registration. Although the current reviewed endovascular navigation systems have shown their potential in phantom and animal studies, clinical trials are too limited to conclude that these systems can improve EVAR outcomes or that they can systematically reduce FTs, radiation doses, and contrast volumes during (complex) EVAR.

Intra-operative 2-D ultrasound and dynamic 3-D aortic model registration for magnetic navigation of transcatheter aortic valve implantation

We propose a navigation system for transcatheter aortic valve implantation that employs a magnetic tracking system (MTS) along with a dynamic aortic model and intra-operative ultrasound (US) images. This work is motivated by the desire of our cardiology and cardiac surgical colleagues to minimize or eliminate the use of radiation in the interventional suite or operating room. The dynamic 3-D aortic model is constructed from a preoperative 4-D computed tomography dataset that is animated in synchrony with the real time electrocardiograph input of patient, and then preoperative planning is performed to determine the target position of the aortic valve prosthesis. The contours of the aortic root are extracted automatically from short axis US images in real-time for registering the 2-D intra-operative US image to the preoperative dynamic aortic model. The augmented MTS guides the interventionist during positioning and deployment of the aortic valve prosthesis to the target. The results of the aortic root segmentation algorithm demonstrate an error of 0.92±0.85 mm with a computational time of 36.13±6.26 ms. The navigation approach was validated in porcine studies, yielding fiducial localization errors, target registration errors, deployment distance, and tilting errors of 3.02±0.39 mm, 3.31±1.55 mm, 3.23±0.94 mm, and 5.85±3.06(°) , respectively.

Improved catheter navigation with 3D electromagnetic guidance

PURPOSE

To evaluate the in vitro performance of an electromagnetic navigation system (ENS) in aortic arch branch cannulation and describe its role for fenestrated endograft deployment.

METHODS

Reconstructed multidetector computed tomography images of silicone phantoms representing the aortic arch and a thoracoabdominal aortic aneurysm were uploaded onto the StealthStation workstation, which provided 3-dimensional visualization of a guidewire by tracking sensors on its tip. For the evaluation of aortic arch branch cannulation, 9 operators were asked to cannulate the phantom's common carotid and left subclavian arteries using the (1) ENS, (2) a 2-dimensional (2D) screen setting simulating fluoroscopy, and (3) both imaging modalities. Analysis included procedure times, number of wall hits, and the Imperial College Complex Cannulation Scoring Tool (IC3ST) qualitative performance score. To evaluate the ability of the ENS during positioning of a fenestrated stent-graft over the visceral segment, a custom-made 4-vessel fenestrated stent-graft with sensors on the fenestrations was deployed 5 consecutive times using the ENS as the exclusive imaging technique.

RESULTS

In the aortic arch model, cannulation times were significantly longer in the ENS group. However, compared with the 2D version, using both imaging modalities reduced fluoroscopic times [median 26.5 seconds (IQR 19.7-30.7) vs. 87 seconds (IQR 64-128), p<0.0001] and wall hits [median 8.5 (IQR 16-38) vs. 14 (IQR 11-160, p<0.05), while improving IC3ST performance scores [31/35 (IQR 30-31.2) vs. 25/35 (IQR 24-27), p<0.05]. Following deployment of the endograft with tracked fenestrations, the 4 visceral vessels were cannulated in all cases using only the ENS.

CONCLUSION

The use of the ENS as a complementary imaging modality might be beneficial in terms of radiation exposure, cannulation performance, and positioning of intravascular devices.

A pilot study on magnetic navigation for transcatheter aortic valve implantation using dynamic aortic model and US image guidance

PURPOSE

In this paper, we propose a pilot study for transcatheter aortic valve implantation guided by an augmented magnetic tracking system (MTS) with a dynamic aortic model and intra-operative ultrasound (US) images.

METHODS

The dynamic 3D aortic model is constructed from the preoperative 4D computed tomography, which is animated according to the real-time electrocardiograph (ECG) input of patient. Before the procedure, the US probe calibration is performed to map the US image coordinate to the tracked device coordinate. A temporal alignment is performed to synchronize the ECG signals, the intra-operative US image and the tracking information. Thereafter, with the assistance of synchronized ECG signals, the spatial registration is performed by using a feature-based registration. Then the augmented MTS guides the surgeon to confidently position and deploy the transcatheter aortic valve prosthesis to the target.

RESULTS

The approach was validated by US probe calibration evaluation and animal study. The US calibration accuracy achieved [Formula: see text], whereas in the animal study on three porcine subjects, fiducial, target, deployment distance and tilting errors reached [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], respectively.

CONCLUSION

Our pilot study has revealed that the proposed approach is feasible and accurate for delivery and deployment of transcatheter aortic valve prosthesis.

Multimodality image fusion-guided procedures: technique, accuracy, and applications

Personalized therapies play an increasingly critical role in cancer care: Image guidance with multimodality image fusion facilitates the targeting of specific tissue for tissue characterization and plays a role in drug discovery and optimization of tailored therapies. Positron-emission tomography (PET), magnetic resonance imaging (MRI), and contrast-enhanced computed tomography (CT) may offer additional information not otherwise available to the operator during minimally invasive image-guided procedures, such as biopsy and ablation. With use of multimodality image fusion for image-guided interventions, navigation with advanced modalities does not require the physical presence of the PET, MRI, or CT imaging system. Several commercially available methods of image-fusion and device navigation are reviewed along with an explanation of common tracking hardware and software. An overview of current clinical applications for multimodality navigation is provided.

Magnetic navigation for thoracic aortic stent-graft deployment using ultrasound image guidance

We propose a system for thoracic aortic stent-graft deployment that employs a magnetic tracking system (MTS) and intraoperative ultrasound (US). A preoperative plan is first performed using a general public utilities-accelerated cardiac modeling method to determine the target position of the stent-graft. During the surgery, an MTS is employed to track sensors embedded in the catheter, cannula, and the US probe, while a fiducial landmark based registration is used to map the patient's coordinate to the image coordinate. The surgical target is tracked in real time via a calibrated intraoperative US image. Under the guidance of the MTS integrated with the real-time US images, the stent-graft can be deployed to the target position without the use of ionizing radiation. This navigation approach was validated using both phantom and animal studies. In the phantom study, we demonstrate a US calibration accuracy of 1.5 ± 0.47 mm, and a deployment error of 1.4 ± 0.16 mm. In the animal study, we performed experiments on five porcine subjects and recorded fiducial, target, and deployment errors of 2.5 ± 0.32, 4.2 ± 0.78, and 2.43 ± 0.69 mm, respectively. These results demonstrate that delivery and deployment of thoracic stent-graft under MTS-guided navigation using US imaging is feasible and appropriate for clinical application.

Three-dimensional electromagnetic navigation vs. fluoroscopy for endovascular aneurysm repair: a prospective feasibility study in patients

PURPOSE

To evaluate the in vivo feasibility of a 3-dimensional (3D) electromagnetic (EM) navigation system with electromagnetically-tracked catheters in endovascular aneurysm repair (EVAR).

METHODS

The pilot study included 17 patients undergoing EVAR with a bifurcated stent-graft. Ten patients were assigned to the control group, in which a standard EVAR procedure was used. The remaining 7 patients (intervention group) underwent an EVAR procedure during which a cone-beam computed tomography image was acquired after implantation of the main stent-graft. The 3D image was presented on the navigation screen. From the contralateral side, the tip of an electromagnetically-tracked catheter was visualized in the 3D image and positioned in front of the contralateral cuff in the main stent-graft. A guidewire was inserted through the catheter and blindly placed into the stent-graft. The placement of the guidewire was verified by fluoroscopy before the catheter was pushed over the guidewire. If the guidewire was incorrectly placed outside the stent-graft, the procedure was repeated. Successful placement of the guidewire had to be achieved within a 15-minute time limit.

RESULTS

Within 15 minutes, the guidewire was placed correctly inside the stent-graft in 6 of 7 patients in the intervention group and in 8 of 10 patients in the control group. In the intervention group, fewer attempts were needed to insert the guidewire correctly.

CONCLUSION

A 3D EM navigation system, used in conjunction with fluoroscopy and angiography, has the potential to provide more spatial information and reduce the use of radiation and contrast during endovascular interventions. This pilot study showed that 3D EM navigation is feasible in patients undergoing EVAR. However, a larger study must be performed to determine if 3D EM navigation is better than the existing practice for these patients.

Electromagnetic tracking for registration and navigation in endovascular aneurysm repair: a phantom study

OBJECTIVE

To assess the feasibility of using an electromagnetic tracking for both registration and navigation in endovascular aneurysm repair.

MATERIALS AND METHODS

A registration process was implemented to align computed tomography (CT) data and electromagnetic tracking data. Two abdominal aortic aneurysm (AAA) phantoms were used, a rigid plastic AAA model (phantom A) and a soft silicon AAA model (phantom B). A pre-procedural CT volume was acquired for each phantom. Intra-operative simulation was performed by placing each phantom in the magnetic field of the tracking device. Using a modified electromagnetic catheter, a set of three-dimensional positions was acquired in the phantom's aortic lumen. Pre-procedural CT images and intra-procedural tracked positions were registered. Four reference points were used to calculate the registration accuracy of phantom A. Three surgeons simulated catheterisation of the left renal artery with phantom B using only image-guided procedure software.

RESULTS

The mean registration error was 1.3 mm (range 0.88-1.89). The median time for left renal catheterisation was 22 s (range 15-59).

CONCLUSION

Registration of CT data and electromagnetic tracking data is feasible using catheter positions in the aorto-iliac structure as landmark. This navigation system could reduce X-ray exposure time and the use of contrast medium injections.

Three-dimensional endovascular navigation with electromagnetic tracking: ex vivo and in vivo accuracy

PURPOSE

To evaluate the accuracy of a 3-dimensional (3D) navigation system using electromagnetically tracked tools to explore its potential in patients.

METHODS

The 3D navigation accuracy was quantified on a phantom and in a porcine model using the same setup and vascular interventional suite. A box-shaped phantom with 16 markers was scanned in 5 different positions using computed tomography (CT). The 3D navigation system registered each CT volume in the magnetic field. A tracked needle was pointed at the physical markers, and the spatial distances between the tracked needle positions and the markers were calculated. Contrast-enhanced CT images were acquired from 6 swine. The 3D navigation system registered each CT volume in the magnetic field. An electromagnetically tracked guidewire and catheter were visualized in the 3D image and navigated to 4 specified targets. At each target, the spatial distance between the tracked guidewire tip position and the actual position, verified by a CT control, was calculated.

RESULTS

The mean accuracy on the phantom was 1.28±0.53 mm, and 90% of the measured distances were ≤1.90 mm. The mean accuracy in swine was 4.18±1.76 mm, and 90% of the measured distances were ≤5.73 mm.

CONCLUSION

This 3D navigation system demonstrates good ex vivo accuracy and is sufficiently accurate in vivo to explore its potential for improved endovascular navigation.

Endovascular image-guided navigation: validation of two volume-volume registration algorithms

The limited volume covered by intraoperatively acquired CT scans makes the use of navigation systems difficult. Preoperative images cover a larger volume of interest. Hence, reliable registration of high quality preoperative to intraoperative CT will provide the necessary image information required for navigation. This study evaluates two algorithms (Siemens, CAMP) for volume-volume registration for usage during endovascular navigation. Twenty patients treated for abdominal aortic aneurysm were scanned with pre-, intra- and postoperative CT. Six data sets were excluded due to variations in image acquisition parameters and severe artifacts. Fourteen intra- and postoperative datasets were registered ten times with both algorithms, altogether 140 registrations for each program. In all data sets five specified landmarks placed by two radiologists were used to evaluate registration accuracy. The distance between the paired landmarks in the registered intra- and postoperative volumes was measured and the root mean square value calculated. Reference registrations were based on rigid body registration of the five landmarks in the intra- and postoperative volumes. Registration accuracy (mean ± SD) was for Siemens 5.05 ± 4.74 mm, for CAMP 4.02 ± 1.52 mm and for the reference registrations 2.72 ± 1.18 mm. The registration algorithms differed significantly, p < 0.001.

Electromagnetic navigation for thoracic aortic stent-graft deployment: a pilot study in swine

PURPOSE

To determine the feasibility of electromagnetic tracking as a method to augment conventional imaging guidance for the safe delivery, precise positioning, and accurate deployment of thoracic aortic endografts.

MATERIALS AND METHODS

Custom guide wires were fabricated, and the delivery catheters for thoracic aortic endoprostheses were retrofitted with integrated electromagnetic coil sensors to enable real-time endovascular tracking. Preprocedure thoracic computed tomographic (CT) angiograms were obtained after the placement of fiducial skin patches on the chest wall of three anesthetized swine, enabling automatic registration. The stent-graft deployment location target near the subclavian artery was selected on the preprocedure CT angiogram. Two steps were analyzed: advancing a tracked glidewire to the aortic arch and positioning the tracked stent-graft assembly by using electromagnetic guidance alone. Multiple CT scans were obtained to evaluate the accuracy of the electromagnetic tracking system by measuring the target registration error, which compared the actual position of the tracked devices to the displayed "virtual" electromagnetic-tracked position. Postdeployment CT angiography and necropsy helped confirm stent-graft position and subclavian artery patency.

RESULTS

A stent-graft was successfully delivered and deployed in each of the three animals by using real-time electromagnetic tracking alone. The mean fiducial registration error with autoregistration was 1.5 mm. Sixteen comparative scans were obtained to determine the target registration error, which was 4.3 mm +/- 0.97 (range, 3.0-6.0 mm) for the glidewire sensor coil. The mean target registration error for the stent-graft delivery catheter sensor coil was 2.6 mm +/- 0.7 (range, 1.9-3.8 mm). The mean deployment error for the stent-graft, defined as deployment deviation from the target, was 2.6 mm +/- 3.0.

CONCLUSIONS

Delivery and deployment of customized thoracic stent-grafts with use of electromagnetic tracking alone is feasible and accurate in swine. Combining endovascular electromagnetic tracking with conventional fluoroscopy may further improve accuracy and be a more realistic multimodality approach.