Dexterous Robots for MRI-Guided Skull Base Surgery
Motivation: Skull base surgery is a highly complex and delicate procedure, primarily due to the need to navigate through narrow, congested areas and remove tissue around critical neurovascular structures. Traditional surgical tools have limited flexibility and dexterity, making it challenging to reach and manipulate target areas without causing collateral damage. MRI guidance during surgery can provide real-time imaging, enhancing precision and safety. However, existing robotic systems for skull base surgery often struggle with MRI compatibility and precise navigation in such confined spaces. To address these challenges, we are developing a highly dexterous, MRI-conditional robotic system specifically designed for transsphenoidal surgery, a common approach for accessing the skull base.
Project Highlights:
In this project, we first designed and developed a preliminary flexible, tendon-driven robotic system with a small diameter (approximately 3 mm) for minimally invasive skull base surgery.
Fig. 1. Endoscopic robot prototype: (a) photo consisting a steerable tip, a rigid shaft, and part of the hydraulic tendon-driven actuation system, (b) steerable tip without sleeve, (c) steerable tip with sleeve.
Fig. 2. Fabrication of the steerable tip: (a) protecting the spring backbone using a straight rigid cable; (b) putting the middle disks on; (c) - (d) adjusting the middle disks using a mold; (e) putting the top and bottom disks on; (f) attaching the tendon wires on; and (g) removing the straight cable and obtaining the steerable tip.
The robot features a two-degree-of-freedom (2-DoF) steerable tip, driven by a hydraulic tendon system, capable of navigating through narrow nasal passages and complex skull base structures. The steerable tip is composed of a superelastic nitinol spring backbone and 3D-printed disks, which together create a flexible, yet stable structure. Four tendon wires, routed through strategically placed holes in the disks, control the motion of the tip, allowing for precise and multidirectional bending. By filling the steerable tip with deionized water, the robot enhances MRI contrast, enabling intraoperative tracking that allows surgeons to adjust the robot’s position in real-time during surgery. Experimental validation has demonstrated the robot’s capability to bend and maneuver within the MRI environment, maintaining high precision without compromising MRI image quality.
Fig. 3. MRI experiment: (a) photo of the robotic system in the MRI coil and (b) schematic of the entire setup.
Fig. 4. Cropped MR images of robot in (a) straight shape, (b) slightly curved shape, and (c) sharply curved shape. On (b) and (c), blue solid curves are fitting curves, orange dash lines are reference lines parallel to water surface. (Note that images are rotated when preparing scripts.) Orange dash arrows are tangent direction at the distal ends of the fit arcs. The numbers indicate the robot bending angles.
The project introduces several key innovations, including the design, modeling, and testing of an MRI-conditional flexible endoscopic robot, a novel hydraulic tendon-driven actuation system. These features make the robot suitable for navigating through the intricate anatomy of the skull base, providing surgeons with a reliable tool for safer and more effective tumor resections. We are currently developing a second version of the robotic system featuring higher degrees of freedom, higher control accuracy, and a new tissue removal mechanism.
Refereed Conference Publications:
Boshen Qi, Hengjie Chen, Jason Langley, Behnam Badie, Xiaoping Hu, and Jun Sheng, “Towards an MRI-Compatible Flexible Endoscopic Robot for Transsphenoidal Neurosurgery,” 2023 IEEE International Symposium on Medical Robotics (ISMR 2023)