No abstract

Endovascular catheterization is an intervention which offers a low risk alternative to open surgery in many patients.Today's interventions rely heavily on fluoroscopic imaging to guide interventionalists. Fluoroscopy only produces 2D visualization of the catheter and also exposes both the patient and interventionalists to harmful radiation. Different approaches have been proposed to overcome the limitations of fluoroscopy. Fiber Bragg Grating (FBG)-based shape sensing is becoming popular to reconstruct the catheter shape. Multi-core fibers with parallel optical cores are interesting as they allow 3D shape reconstruction with a single fiber. A common issue with FBG-based shape sensing is its sensitivity to variations in twist. Even small amounts of twist can significantly impact the overall shape reconstruction accuracy. This work proposes a novel approach which combines electromagnetic tracking (EMT), FBG-based shape sensing, and sparse fluoroscopic images. The method provides realtime 3D visualization of the catheter without the need of continuous fluoroscopy. A unique feature of the proposed method is the selective use of imaging for dynamic twist-compensation of the FBG sensor. The proposed sensor-fusion method improved 3D reconstruction accuracy. Real-world in-vitro experiments promising results. For a catheter with an embedded fiber length of 170 mm, the proposed approach the 3D shape with a median root-mean-square (rms) error of 0.39 mm and an interquartile range of 0.10 mm in the 2D experiment in which the catheter was bent in a plane. A median rms error of 0.54 mm and an interquartile range of 0.07 mm were achieved in the 3D experiments.

<p>In this paper, we propose a novel method to improve the shape sensing accuracy of FBG for catheter by fusing FBG-based sensed shape with sparse fluoroscopic images. The main advantage of the new proposed method compared to other methods are the limited number in fluoroscopic image used during procedure while it still maintains high precision real-time 3D visualization of the catheter. To demonstrate the performance of the proposed method 2D and 3D dynamic experiments were carried out and they shows promising results. For a catheter with an embedded fiber length of 170 mm, the proposed approach can reconstruct the 3D shape with a median root mean square error of 0.54 mm were seen in the 3D experiments compared to the traditional approach of using FBG alone of 0.86 mm.</p>

A variety of medical treatment and diagnostic procedures rely on flexible instruments such as catheters and endoscopes to navigate through tortuous and soft anatomies like the vasculature. Knowledge of the interaction forces between these flexible instruments and patient anatomy is extremely valuable. This can aid interventionalists in having improved awareness and decision-making abilities, efficient navigation, and increased procedural safety. In many applications, force interactions are inherently distributed. While knowledge of their locations and magnitudes is highly important, retrieving this information from instruments with conventional dimensions is far from trivial. Robust and reliable methods have not yet been found for this purpose. In this work, we present two new approaches to estimate the location, magnitude, and number of external point and distributed forces applied to flexible and elastic instrument bodies. Both methods employ the knowledge of the instrument’s curvature profile. The former is based on piecewise polynomial-based curvature segmentation, whereas the latter on model-based parameter estimation. The proposed methods make use of Cosserat rod theory to model the instrument and provide force estimates at rates over 30 Hz. Experiments on a Nitinol rod embedded with a multi-core fiber, inscribed with fiber Bragg gratings, illustrate the feasibility of the proposed methods with mean force error reaching 7.3% of the maximum applied force, for the point load case. Furthermore, simulations of a rod subjected to two distributed loads with varying magnitudes and locations show a mean force estimation error of 1.6% of the maximum applied force.

Nowadays, navigating therapeutic catheters takes place under 2D fluoroscopic imaging. This requires considerable training of the clinician and exposes him/her to X-ray radiation. Researchers have increasingly investigated alternative sensing techniques. In this respect, Fiber Bragg Grating (FBG)-based shape sensing is gaining popularity. This paper proposes two approaches to fuse FBG with fluoroscropy, improve the understanding of the 3-dimensional shape while reducing fluoroscopy use. This paper proposes two FBG-fluoroscopy fusion approaches that combine fluoroscopy and FBG measurements. A comparison is performed between 3D shape reconstructions based on biplane fluoroscopy, rigidly fused multi-core FBG and dynamically fused FBG shape reconstruction. To verify the performance of the different approaches experiments were performed with custom made catheter in a CathLab on 3D printed tubes with known ground truth shape. The experiments showed overall acceptable errors for the targeted application with a maximum below 2 mm. The error of shape reconstruction through biplane fluoroscopy, rigid and dynamic fusion were found to be 1.51 ± 0.04 mm, 1.77 ± 0.29 mm and 1.47 ± 0.15 mm, respectively. Thus, FBGfluoroscopy fusion offers comparable results to fluoroscopy and may substantially reduce the radiation dose through optimal acquisition frequency.