Intravascular catheter navigation using path planning and virtual visual feedback for oral cancer treatment

Diameters of lingual, facial, and maxillary arteries measured according to an objective protocol on 3D computed tomography angiography images

PURPOSE

Retrograde superselective intra-arterial chemoradiotherapy is a radical treatment for advanced oral cancer. The catheter tip is placed into tumor-feeding arteries-the lingual, facial, or maxillary arteries. The diameter of the tumor-feeding arteries newly bifurcated from the external carotid artery is crucial for determining the requirement of a catheter navigation system. This study aimed to measure the diameter and distribution of the tumor-feeding artery according to an objective protocol using 3D computed tomography angiography images reproducibly.

METHODS

Angiographic data of 20 noncatheterized carotid arteriesof 10 randomly selected patients were analyzed. We followed the external carotid artery to the entrance of each feeding artery to determine the center point where the artery diameter was measured. The diameter of the optimum circle measured at the adopted center point was taken as the diameter of each tumor-feeding artery.

RESULTS

The diameters (mean ± standard deviation) were 3.5 ± 0.45, 2.9 ± 0.56, and 3.5 ± 0.56 mm for the maxillary, lingual, and facial arteries, respectively. The diameters of the maxillary and facial arteries were similar (p = 0.877), whereas the diameter of the lingual artery was smaller than that of the maxillary and facial arteries (p < 0.001).

CONCLUSION

The findings of this study will be beneficial in determining the need of a new catheter navigation system and diameter of catheters to be used in the clinical practice. From the viewpoint of measurement automation and reproducibility, 3DCTA vessel measurement taken according to the proposed protocol was considered to be effective.

A pilot study on an electromagnetic tracking system using tunneling magnetoresistance (TMR) sensors applicable to a 4F catheter (1.4 mm in diameter)

PURPOSE

Tracking the position and orientation of a 4F catheter ([Formula: see text] 1.4 mm) is required in superselective intra-arterial chemotherapy (SSIAC). Tunneling magnetoresistance (TMR) sensors, which measure magnetic fields, are promising candidates because the size of the TMR sensor can be less than a few tenths of a millimeter. The purpose of this paper is to prove the feasibility of an EMT system utilizing TMR sensors as magnetometers.

METHODS

Three 1-axis TMR sensors (0.3 mm × 0.3 mm) were packaged on a flexible printed circuit board (PCB) together with an amplifier chip. The PCB was integrated into a 4F catheter. Six field generator coils driven by alternating current (AC) at different frequencies were used. Magnetic field measurement errors were evaluated to assess the effect of electromotive force (EMF) on TMR-based sensing by changing the coils' driving frequencies. The tracking error was also evaluated. As a result, the feasibility of catheter navigation utilizing the EMT system was demonstrated.

RESULTS

There was a positive correlation between the frequency and the magnetic field measurement error using the TMR sensor (R² = 0.999). With magnetic field frequencies less than 603 Hz, the average position and orientation estimation error were 10.1 mm and 2.3 degree, respectively. Under ideal conditions, the average estimation error values were 0.9 mm and 0.3 degree, respectively.

CONCLUSION

The position and orientation errors varied with frequency owing to the induced electromotive force. We should consider the effect of electromotive force on TMR sensor assemblies caused by alternating magnetic fields. An EMT system using TMR sensors was validated, although room for further improvement was identified.

A hybrid inductive learning-based and deductive reasoning-based 3-D path planning method in complex environments

Traditional path planning methods, such as sampling-based and iterative approaches, allow for optimal path’s computation in complex environments. Nonetheless, environment exploration is subject to rules which can be obtained by domain experts and could be used for improving the search. The present work aims at integrating inductive techniques that generate path candidates with deductive techniques that choose the preferred ones. In particular, an inductive learning model is trained with expert demonstrations and with rules translated into a reward function, while logic programming is used to choose the starting point according to some domain expert’s suggestions. We discuss, as use case, 3-D path planning for neurosurgical steerable needles. Results show that the proposed method computes optimal paths in terms of obstacle clearance and kinematic constraints compliance, and is able to outperform state-of-the-art approaches in terms of safety distance-from-obstacles respect, smoothness, and computational time.

Transpathology: molecular imaging-based pathology

Pathology is the medical specialty concerned with the study of the disease nature and causes, playing a key role in bridging basic researches and clinical medicine. In the course of development, pathology has significantly expanded our understanding of disease, and exerted enormous impact on the management of patients. However, challenges facing pathology, the inherent invasiveness of pathological practice and the persistent concerns on the sample representativeness, constitute its limitations. Molecular imaging is a noninvasive technique to visualize, characterize, and measure biological processes at the molecular level in living subjects. With the continuous development of equipment and probes, molecular imaging has enabled an increasingly precise evaluation of pathophysiological changes. A new pathophysiology visualization system based on molecular imaging is forming and shows the great potential to reform the pathological practice. Several improvements in "trans-," including trans-scale, transparency, and translation, would be driven by this new kind of pathological practice. Pathological changes could be evaluated in a trans-scale imaging mode; tissues could be transparentized to better present the underlying pathophysiological information; and the translational processes of basic research to the clinical practice would be better facilitated. Thus, transpathology would greatly facilitate in deciphering the pathophysiological events in a multiscale perspective, and supporting the precision medicine in the future.

Visual-electromagnetic system: A novel fusion-based monocular localization, reconstruction, and measurement for flexible ureteroscopy

BACKGROUND

During flexible ureteroscopy (FURS), surgeons may lose orientation due to intrarenal structural similarities and complex shape of the pyelocaliceal cavity. Decision-making required after initially misjudging stone size will also increase the operative time and risk of severe complications.

METHODS

A intraoperative navigation system based on electromagnetic tracking (EMT) and simultaneous localization and mapping (SLAM) was proposed to track the tip of the ureteroscope and reconstruct a dense intrarenal three-dimensional (3D) map. Furthermore, the contour lines of stones were segmented to measure the size.

RESULTS

Our system was evaluated on a kidney phantom, achieving an absolute trajectory accuracy root mean square error (RMSE) of 0.6 mm. The median error of the longitudinal and transversal measurements was 0.061 and 0.074 mm, respectively. The in vivo experiment also demonstrated the effectiveness.

CONCLUSION

The proposed system worked effectively in tracking and measurement. Further, this system can be extended to other surgical applications involving cavities, branches and intelligent robotic surgery.

Applicability of a single camera-based catheter navigation system using teeth arch as an anatomical landmark for superselective intraarterial infusion in advanced oral cancer treatment

Superselective intraarterial infusion chemoradiotherapy is a modality of oral cancer therapy in which the artery feeding the tumor is catheterized. 3D information about the carotid artery is required to enable the surgeon to judge whether to advance, retract, or rotate the catheter. For this purpose, we proposed and conducted a model experiment to assess a new method of catheterization that applies a tracking system using registration with a monocular camera using the maxillary arch as the anatomical landmark. In this method, the preoperative 3D computer tomography angiographic image of the carotid artery that the catheter will be passed through is overlaid on the 2D video image. The mean TRE was 0.96 ± 0.36 mm and 0.88 ± 0.31 mm and 1.12 ± 0.46 mm when images were registered with the anterior and posterior teeth as the landmarks, respectively; the difference was not significant (p = 0.21). This tracking system that enables markerless registration simply by taking images of the maxillary anterior teeth with a single camera was convenient and effective for catheterization. In this study, we propose the new application of this tracking system and a novel method of catheterization for superselective intraarterial infusion chemoradiotherapy for oral cancer.

Experimental investigation of a twisted string actuation for usage in active catheter

BACKGROUND

The improvement of the steerability and controllability of catheters is highly required because catheter-based interventional diagnosis and therapy have become increasingly popular. However, active catheters are often complex and expensive.

METHODS

This study attempts to control catheter tip by a twisted string actuator. Experiments are carried out to analyze the full actuation and bending characteristics of the active catheter.

RESULTS

It is indicated that the expected bending motion can be achieved by twisting the strings. Hysteresis behavior in backward and forward motion is also discussed. High repetitive positional accuracy and reverse position accuracy can be obtained when the number of rotation is low. When the number of turns is 25, the maximum tip position errors are 4, 1.8 and 1 mm in X, Y and Z directions, respectively.

CONCLUSION

It is expected that the presented method will prove useful for the application of twisted string active catheter.

Knee arthroscopic navigation using virtual-vision rendering and self-positioning technology

PURPOSE

Knee arthroscopy suffers from a lack of depth information and easy occlusion of the visual field. To solve these limitations, we propose an arthroscopic navigation system based on self-positioning technology, with the guidance of virtual-vision views. This system can work without any external tracking devices or added markers, thus increasing the working range and improving the robustness of the rotating operation.

METHODS

The fly-through view and global positioning view for surgical guidance are rendered through virtual-vision rendering in real time. The fly-through view provides surgeons with navigating the arthroscope in the internal anatomical structures using a virtual camera perspective. The global positioning view shows the posture of the arthroscope relative to the preoperative model in a transparent manner. The posture of the arthroscope is estimated from the fusion of visual and inertial data based on the visual-inertial stereo slam. A flexible calibration method that transforms the posture of the arthroscope in the physical world into the virtual-vision rendering framework is proposed for the arthroscopic navigation system with self-positioning information.

RESULTS

Quantitative experiments for evaluating self-positioning accuracy were performed. For translation, the acquired mean error was 0.41 ± 0.28 mm; for rotation, it was 0.11° ± 0.07°. The tracking range of the proposed system was approximately 1.4 times that of the traditional external optical tracking system for the rotating operation. Simulated surgical operations were performed on the phantom. The fly-through and global positing views were paired with original arthroscopic images for intuitive surgical guidance.

CONCLUSION

The proposed system provides surgeons with both fly-through and global positioning views without a dependence on the traditional external tracking systems for surgical guidance. The feasibility and robustness of the system are evaluated, and it shows promise for medical applications.

A marker-based contactless catheter-sensing method to detect surgeons' operations for catheterization training systems

It is challenging to position a catheter or a guidewire within a patient's complicated and delicate vascular structure due to the lack of intuitive visual feedback by only manipulating the proximal part of the surgical instruments. Training is therefore critical before an actual surgery because any mistake due to the surgeon's inexperience can be fatal for the patient. The catheter manipulation skills of experienced surgeons can be useful as input for training novice surgeons. However, few research groups focused on designs with consideration of the contactless catheter motion measurement, which allows obtaining expert surgeons' catheter manipulation trajectories whilst still allowing them to employ an actual catheter and apply conventional pull, push and twist of the catheter as used in bedside intravascular interventional surgeries. In this paper, a novel contactless catheter-sensing method is proposed to measure the catheter motions by detecting and tracking a passive marker with four feature-point groups. The passive marker is designed to allow simultaneously sensing the translational and rotational motions of the input catheter. Finally, the effectiveness of the proposed contactless catheter-sensing method is validated by conducting a series of comparison experiments. The accuracy and error analysis are quantified based on the absolute error, relative error, mean absolute error, and the success rate of the detection.

3D Catheter Shape Determination for Endovascular Navigation Using a Two-Step Particle Filter and Ultrasound Scanning

In endovascular catheter interventions, the determination of the three-dimensional (3D) catheter shape can increase navigation information and help reduce trauma. This study describes a shape determination method for a flexible interventional catheter using ultrasound scanning and a two-step particle filter without X-ray fluoroscopy. First, we propose a multi-feature, multi-template particle filter algorithm for accurate catheter tracking from ultrasound images. Second, we model the mechanical behavior of the catheter and apply a particle filter shape optimization algorithm to refine the results from the first step. Finally, the acquired catheter's 3D shapes are displayed together with the preoperative 3D images of the cardiac structures to provide intuitive endovascular navigation. We validated our method using ultrasound scanning of the straight and curved catheters in a water tank, and the shape determination errors were 1.44 ± 0.38 mm and 1.95 ± 0.46 mm, respectively. Further, endovascular catheter shape determination was validated in a catheter intervention experiment with a heart phantom. The error of the acquired endovascular catheter shape was 2.23 ± 0.87 mm. These results demonstrate that our two-step method is both accurate and effective. Using ultrasound scanning for shape determination of a flexible catheter will be helpful in endovascular interventions, reducing exposure to radiation and providing rich navigation information.

Video see-through augmented reality for oral and maxillofacial surgery

BACKGROUND

Oral and maxillofacial surgery has not been benefitting from image guidance techniques owing to the limitations in image registration.

METHODS

A real-time markerless image registration method is proposed by integrating a shape matching method into a 2D tracking framework. The image registration is performed by matching the patient's teeth model with intraoperative video to obtain its pose. The resulting pose is used to overlay relevant models from the same CT space on the camera video for augmented reality.

RESULTS

The proposed system was evaluated on mandible/maxilla phantoms, a volunteer and clinical data. Experimental results show that the target overlay error is about 1 mm, and the frame rate of registration update yields 3-5 frames per second with a 4 K camera.

CONCLUSIONS

The significance of this work lies in its simplicity in clinical setting and the seamless integration into the current medical procedure with satisfactory response time and overlay accuracy. Copyright © 2016 John Wiley & Sons, Ltd.

Motion-adapted catheter navigation with real-time instantiation and improved visualisation

The improvements to catheter manipulation by the use of robot-assisted catheter navigation for endovascular procedures include increased precision, stability of motion and operator comfort. However, navigation through the vasculature under fluoroscopic guidance is still challenging, mostly due to physiological motion and when tortuous vessels are involved. In this paper, we propose a motion-adaptive catheter navigation scheme based on shape modelling to compensate for these dynamic effects, permitting predictive and dynamic navigations. This allows for timed manipulations synchronised with the vascular motion. The technical contribution of the paper includes the following two aspects. Firstly, a dynamic shape modelling and real-time instantiation scheme based on sparse data obtained intra-operatively is proposed for improved visualisation of the 3D vasculature during endovascular intervention. Secondly, a reconstructed frontal view from the catheter tip using the derived dynamic model is used as an interventional aid to user guidance. To demonstrate the practical value of the proposed framework, a simulated aortic branch cannulation procedure is used with detailed user validation to demonstrate the improvement in navigation quality and efficiency.

Design and performance evaluation of a master controller for endovascular catheterization

PURPOSE

It is difficult to manipulate a flexible catheter to target a position within a patient's complicated and delicate vessels. However, few researchers focused on the controller designs with much consideration of the natural catheter manipulation skills obtained from manual catheterization. Also, the existing catheter motion measurement methods probably lead to the difficulties in designing the force feedback device. Additionally, the commercially available systems are too expensive which makes them cost prohibitive to most hospitals. This paper presents a simple and cost-effective master controller for endovascular catheterization that can allow the interventionalists to apply the conventional pull, push and twist of the catheter used in current practice.

METHODS

A catheter-sensing unit (used to measure the motion of the catheter) and a force feedback unit (used to provide a sense of resistance force) are both presented. A camera was used to allow a contactless measurement avoiding additional friction, and the force feedback in the axial direction was provided by the magnetic force generated between the permanent magnets and the powered coil.

RESULTS

Performance evaluation of the controller was evaluated by first conducting comparison experiments to quantify the accuracy of the catheter-sensing unit, and then conducting several experiments to evaluate the force feedback unit. From the experimental results, the minimum and the maximum errors of translational displacement were 0.003 mm (0.01 %) and 0.425 mm (1.06 %), respectively. The average error was 0.113 mm (0.28 %). In terms of rotational angles, the minimum and the maximum errors were 0.39°(0.33 %) and 7.2°(6 %), respectively. The average error was 3.61°(3.01 %). The force resolution was approximately 25 mN and a maximum current of 3A generated an approximately 1.5 N force.

CONCLUSION

Based on analysis of requirements and state-of-the-art computer-assisted and robot-assisted training systems for endovascular catheterization, a new master controller with force feedback interface was proposed to maintain the natural endovascular catheterization skills of the interventionalists.

Current and emerging robot-assisted endovascular catheterization technologies: a review

Endovascular techniques have been embraced as a minimally-invasive treatment approach within different disciplines of interventional radiology and cardiology. The current practice of endovascular procedures, however, is limited by a number of factors including exposure to high doses of X-ray radiation, limited 3D imaging, and lack of contact force sensing from the endovascular tools and the vascular anatomy. More recently, advances in steerable catheters and development of master/slave robots have aimed to improve these practices by removing the operator from the radiation source and increasing the precision and stability of catheter motion with added degrees-of-freedom. Despite their increased application and a growing research interest in this area, many such systems have been designed without considering the natural manipulation skills and ergonomic preferences of the operators. Existing studies on tool interactions and natural manipulation skills of the operators are limited. In this manuscript, new technical developments in different aspects of robotic endovascular intervention including catheter instrumentation, intra-operative imaging and navigation techniques, as well as master/slave based robotic catheterization platforms are reviewed. We further address emerging trends and new research opportunities towards more widespread clinical acceptance of robotically assisted endovascular technologies.

Vessel bifurcation localization based on intraoperative three-dimensional ultrasound and catheter path for image-guided catheter intervention of oral cancers

We present a method to localize intraoperative target vessel bifurcations under bones for ultrasound (US) image-guided catheter interventions. A catheter path is recorded to acquire skeletons for the target vessel bifurcations that cannot be imaged by intraoperative US. The catheter path is combined with the centerlines of the three-dimensional (3D) US image to construct a preliminary skeleton. Based on the preliminary skeleton, the orientations of target vessels are determined by registration with the preoperative image and the bifurcations were localized by computing the vessel length. An accurate intraoperative vessel skeleton is obtained for correcting the preoperative image to compensate for vessel deformation. A reality check of the proposed method was performed in a phantom experiment. Reasonable results were obtained. The in vivo experiment verified the clinical workflow of the proposed method in an in vivo environment. The accuracy of the centerline length of the vessel for localizing the target artery bifurcation was 2.4mm. These results suggest that the proposed method can allow the catheter tip to stop at the target artery bifurcations and enter into the target arteries. This method can be applied for virtual reality-enhanced image-guided catheter intervention of oral cancers.

Stereotactic endovascular aortic navigation with a novel ultrasonic-based three-dimensional localization system

BACKGROUND

Endovascular aortic procedures have been developed to treat many aortic diseases effectively. However, these procedures are also becoming increasingly complex given the development of branched or fenestrated endografts. Part of the difficulty lies in the limitations of current imaging paradigms. A more intuitive, three-dimensional (3D) mode of intraoperative imaging is desirable to accommodate the future progression of endovascular techniques. This article describes a novel endovascular catheter tracking device that uses ultrasonic signals, not ultrasound imaging. The tracking device displays real-time in vivo location on previously acquired 3D computed tomography (CT) images in an intuitive, endoluminal view. This system was tested in two swine and validated against fluoroscopy and by delivering stent grafts.

METHODS

The ultrasonic-based localization system (ULS) provides real-time location information of a modified endovascular catheter and displays this location on preoperative 3D CT images. The 9F endovascular catheter has a small ultrasonic transmitter attached to its tip to signal its location to the ULS. Subsequent endovascular deployment of an aortic stent was carried out using only the ULS to target the stent placement position in the aorta of Yorkshire swine. System accuracy was measured against concurrent angiography as well as to deployed stents in situ.

RESULTS

We successfully displayed the endovascular catheter tip location in real time along the registered CT aortic images, providing virtual endoluminal tracking. The relative accuracy of the ULS as compared with angiography for catheter movements in the abdominal aorta was found to have a mean error less than 1 mm. The ULS coordinates tracked within the lumen of the aortic image 98% of the time, as defined by the proportion of points within one radius distance of the aortic image centerline. Finally, three aortic stents were deployed using the ULS virtual image display to locate the target position in the aorta for stent deployment. Errors between target position and actual stent position ranged from -5.0 to +7.9 mm.

CONCLUSIONS

This study demonstrates the feasibility of virtual image-guided endovascular aortic navigation using a ULS. This provides a 3D platform for virtual navigation on preoperative CT scan images during endovascular procedures that could assist in stent deployment as well as minimize or eliminate the need for procedural ionizing radiation and iodinated contrast. Future work will focus on miniaturization and refinements in accuracy that will be required to translate this technology into clinical application in endovascular procedures.

Analysis of carotid artery deformation in different head and neck positions for maxillofacial catheter navigation in advanced oral cancer treatment

Background

To improve the accuracy of catheter navigation, it is important to develop a method to predict shifts of carotid artery (CA) bifurcations caused by intraoperative deformation. An important factor affecting the accuracy of electromagnetic maxillofacial catheter navigation systems is CA deformations. We aimed to assess CA deformation in different head and neck positions.

Methods

Using two sets of computed tomography angiography (CTA) images of six patients, displacements of the skull (maxillofacial segments), C1–C4 cervical vertebrae, mandible (mandibular segment), and CA along with its branches were analyzed. Segmented rigid bones around CA were considered the main causes of CA deformation. After superimposition of maxillofacial segments, C1–C4 and mandible segments were superimposed separately for displacement measurements. Five bifurcation points (vA–vE) were assessed after extracting the CA centerline. A new standardized coordinate system, regardless of patient-specific scanning positions, was employed. It was created using the principal axes of inertia of the maxillofacial bone segments of patients. Position and orientation parameters were transferred to this coordinate system. CA deformation in different head and neck positions was assessed.

Results

Absolute shifts in the center of gravity in the bone models for different segments were C1, 1.02 ± 0.9; C2, 2.18 ± 1.81; C3, 4.25 ± 3.85; C4, 5.90 ± 5.14; and mandible, 1.75 ± 2.76 mm. Shifts of CA bifurcations were vA, 5.52 ± 4.12; vB, 4.02 ± 3.27; vC, 4.39 ± 2.42; vD, 4.48 ± 1.88; and vE, 2.47 ± 1.32. Displacements, position changes, and orientation changes of C1–C4 segments as well as the displacements of all CA bifurcation points were similar in individual patients.

Conclusions

CA deformation was objectively proven as an important factor contributing to errors in maxillofacial navigation. Our study results suggest that small movements of the bones around CA can result in small CA deformations. Although patients’ faces were not fixed properly during CT scanning, C1–C4 and vA–vE displacements were similar in individual patients. We proposed a novel method for accumulation of the displacement data, and this study indicated the importance of surrounding bone displacements in predicting CA bifurcation.