Ultrasound (US) imaging catheters are flexible instruments that are introduced through the patient's vasculature and steered to the heart. These catheters feature an ultrasound transducer at the distal tip, which provides real-time, high frame rate 2D US images to the clinicians for procedure guidance. Steering the US imager by hand and aligning the imaging plane with a target to obtain adequate views is a challenging and time-consuming process. Therefore, many clinicians prefer to only use US catheters while performing critical tasks. To increase the utility of these high-quality imaging devices, we developed a robotic system for automatically guiding US imaging catheters within the heart.
Figure 1: US catheter manipulation robot prototype.
Accurately maneuvering the 4-DOF catheter in vivo requires a controller that is robust to a number of inaccuracies and disturbances. Two electromagnetic (EM) tracking sensors are used to resolve the configuration of the catheter tip. One sensor is placed at the tip of the bending section, proximal to the US transducer such that the US beam is not distorted. The second sensor is placed at the base of the bending section to resolve physiological disturbances from the environment and the unmodeled behavior of the catheter body.
Our robotic system enables capabilities that are not available through manual steering of the catheter. For example, by rotating the catheter about a fixed axis, 2D US images can be collected and reconstructed into a 3D or 4D volume to enable anatomical mapping and procedure guidance.
Figure 2: In vivo 3D reconstruction of an ablation catheter inserted into the right ventricle.
As part of this project, I am developing high-performance algorithms for real-time compounding of 2D US slices into 3D and 4D volumes. I make use of parallel computing, both on the CPU and the GPU, in order to ensure real-time performance. The generated volumes are then rendered using ray-casting methods, also in real-time, making use of the CUDA-OpenGL interoperability. Our work on Advanced Real-Time Visualization for Robotic Heart Surgery was recently featured on the NVIDIA Developer website.
Publications:
- A. Degirmenci, P. M. Loschak, C. M. Tschabrunn, E. Anter, and R. D. Howe, “Compensation for Unconstrained Catheter Shaft Motion in Cardiac Catheters,” IEEE International Conference on Robotics and Automation (ICRA). In Press, 2016.
- P. M. Loschak, A. Degirmenci, Y. Tenzer, C. M. Tschabrunn, E. Anter, and R. D. Howe, “A 4-DOF Robot for Positioning Ultrasound Imaging Catheters,” ASME Journal of Mechanisms and Robotics, 2015.
- P. M. Loschak, A. Degirmenci, L. J. Brattain, and R. D. Howe, “Automatic Steering of Cardiac Imaging Catheters,” Workshop on Navigation and Actuation of Flexible Instruments in Medical Applications (NAFIMA) at IROS 2015. 2015.
- P. M. Loschak, Y. Tenzer, A. Degirmenci, and R. D. Howe, “A 4-DOF Robot for Positioning Ultrasound Imaging Catheters,” Proceedings of the ASME 2015 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference (IDETC/CIE 2015). 2015.