Fluid-driven robotic systems for intraoperative MRI-guided interventions

Abstract

Recent years have witnessed the rapid development and growing popularity of image-guided surgery. Magnetic resonance imaging (MRI) is well-known for its superior capability in providing non-invasive high-contrast images of soft tissues without ionizing radiation. It is also capable of monitoring the temperature changes during thermal therapies. These advantages have prompted MRI for vibrant applications ranging from biopsy, laser ablation, drug injection, to catheterization. Numerous patient trials have demonstrated the clinical values with the use of intra-operative (intra-op) MRI. However, these procedures could be still time-consuming and complicated by the lack of efficient manipulation with real-time navigation. It is timely to benefit from the recent advances in robotics for enhanced surgical manipulation and simplified workflow.

The main focus of this thesis is concerned with fluid-powered actuation and robotic manipulator designs that enable high-performance MR safe surgical manipulation under continuous intra-op MRI guidance. The use of ferromagnetic materials is forbidden in the strong magnetic field of MRI scanner. Conductive components, including electric wires and most metallic components, may generate heat by electromagnetic (EM) induction and induce image artefact/distortion. In this context, novel actuators driven by fluidic power, i.e. a customizable pneumatic stepper motor and high-fidelity master-slave hydraulic transmission, are proposed to provide intrinsically MR safe actuation. The kinematics and dynamics models have been studied, which facilitate the overall design optimization. The hydraulic transmissions have been integrated into a robotic manipulator for intra-cardiac electrophysiology (EP) catheterization. Multiple simulated clinical tasks have been carried out to validate the manipulation dexterity and efficiency. Furthermore, advanced MR-based wireless positional tracking markers have also been investigated, which can provide real-time instrument localization directly in the imaging domain. Incorporated with these wireless trackers and a novel fluid-tendon actuation mechanism, a neurosurgical robotic system has been developed to perform bilateral stereotaxy. Its compact design can be accommodated inside a standard head coil based on a single invasive anchorage. Transmission stiffness, targeting accuracy and MRI compatibility have been evaluated towards the application in deep brain stimulation (DBS). Pre-clinical trial has been conducted under the MRI to validate the proposed simplified workflow. A soft robotic manipulator powered by hydraulics has been designed for transoral laser dissection. Targeting accuracy at submillimetre level has been demonstrated in the path-following tests. MRI-guided navigation has been conducted for ex vivo tissue ablation.