Closed-Loop Control of a Magnetically-Actuated Catheter Using Two-Dimensional Ultrasound Images

Robotically-actuated catheters are being employed in endovascular interventions for their improved maneuverability and steering precision over conventional catheters. Fluoroscopy is commonly used to guide such medical devices during interventions. Motivated by the limitations and hazards associated with fluoroscopy, this study investigates the use of ultrasound images as a viable alternative for the real-time visualization of a robotic catheter. In order to validate the proposed approach, an integrated system is developed which employs a two-dimensional ultrasound-based tracking algorithm to detect and track a magnetically-actuated catheter. By using Euler-Bernoulli beam theory to describe the motion of the catheter and a closed-loop control, the magnetic field steers the robotic catheter in two-dimensional space. Experiments show that the model is able to describe the catheter deflections with a fitting error of R-2 = 0.96. Closed-loop steering experiments show a maximum positioning error of 0.46 mm. Our study demonstrates the possibility to accurately steer a magnetic catheter using two-dimensional ultrasound images.