Wim-Alexander Beckers

In current clinical practice, fluoroscopy is used to track the catheter shape during endovascular navigation. To reduce radiation exposure for clinicians and patients, alternative approaches relying on electromagnetic (EM) tracking and fiber-optic shape sensing (FOSS) have been investigated. EM sensors can be fragile and sensitive to EM disturbances. FOSS alone does not provide localization which is essential for catheter navigation. In this work, a method for localizing a catheter’s shape-sensing fiber with respect to a static reference frame without relying on additional sensors is proposed. The method exploits the approximate follow-the-leader motion that typically arises during catheter insertion. The proposed approach foresees hereto a method to dynamically identify stable reference segments to be used for localization. This method explores the potential to offer both shape sensing and localization with a single shape sensing fiber. The proposed method was validated in 3D vessel mock-ups. Results demonstrate the feasibility of the approach, with tip localization errors of −0.29 $\pm$ 1.86 mm and 3.82 $\pm$ 2.66 mm along and perpendicular to the vessel centerline, respectively, achieved over insertion depths up to 800 mm. This work offers an important step toward reducing reliance on radiation-based imaging and EM sensors in catheter-based interventions.

Despite continuous advances in three-dimensional (3D) fusion imaging, two-dimensional (2D) X-ray-based fluoroscopy is still the gold standard intra-operative image guidance tool in endovascular interventions. The adoption of robotic technology offers the potential to bring intra-operative radiation exposure down to a minimum, or even eliminate it. Non-ionizing approaches, such as Intravascular Ultrasound (IVUS), are progressively explored as standalone or fluoroscopy-adjunct techniques for 3D vasculature reconstruction. We have previously demonstrated the feasibility of real-time 3D Main Vessel (MV) modeling from the fusion of IVUS and EM pose data obtained from sensors embedded at the tip of a robotic catheter. This paper proposes to advance MV modeling towards a comprehensive radiation-free 3D guidance framework by means of intra-operative Side Branch (SB) detection and modeling. Two models are proposed to approximate the geometry of SB vessel ostia: a sphere and a cylinder. An Unscented Kalman Filter (UKF) recursively estimates the state of these models considering the MV model, while the catheters navigates through the vessel. In silico and in vitro validation results show the potential clinical value of the proposed strategy for facilitating safer robotic catheter steering.

Superelastic notched tube instruments are being increasingly employed in surgical robotics. Due to their superelastic material properties, they can achieve small bending radii even for large bending angles, which makes them very interesting for minimally invasive interventions, typically dealing with confined spaces. Several works have aimed to model the behavior of such tubes in regard to the actuation force. The most extensive considers the superelastic material properties as well as the friction between the instrument and the tendon. However, no model is able to capture both the hysteresis behavior of the superelastic material as well as the hysteresis behavior induced by the friction. This text proposed a quasi-static method for modeling the behavior of nitinol notched tube instruments accounting for both material- and friction-induced hysteresis. The model is validated on four samples and compared to state of the art models. Results show an average notch position root mean square error of 1.06 mm (5.5%) and 0.46 mm (2.4%) for the method with measured parameters and optimized parameters, respectively.