Minimally Invasive Neurosurgical Robot for MRI-Guided Intratumoral Therapeutic Delivery

This paper presents the design, modeling, and feasibility study of a magnetic resonance (MR)-conditional steerable neurosurgical robot for minimally invasive intratumoral delivery of therapeutic agents. Immunotherapy is an emerging brain tumor treatment technique but faces challenges due to low trafficking with systemic infusions, particularly in the case of large tumors. To address this limitation, we have developed a novel robotic system capable of delivering therapeutic agents throughout the entire volume of the brain tumor. The robot consists of a straight, rigid outer tube and a flexible inner tube that can navigate along curved paths and articulate in 3D space. A custom-designed injection mechanism consisting of syringes and hydraulic transmission is integrated into the robotic system. A non-magnetic actuation system enables robot navigation to various locations within the tumor. Therefore, by delivering therapeutic agents to individual target locations, the overall trafficking and efficiency can be potentially improved. Characterization-based control experiments yielded a curvature control error of 2.6±1.8% and a relative tip tracking error of 4.2±3.9%, demonstrating the high accuracy of our control strategy. A phantom study demonstrated a significant improvement of the tumor coverage ratio made by the robotic needle compared to the straight needle (73% vs. 29%). An MRI-guided manipulation study showed an acceptable decrease in the signal-to-noise ratio (up to 1.41%) when the robot is manipulated in the water phantom. All these studies synergistically validated the feasibility of our new approach of robotically steerable, MRI-guided therapeutic delivery.