Design of an MR-compatible biopsy needle manipulator using pull-pull cable transmission

Abstract

Magnetic resonance (MR) compatible needle manipulators can assist physicians with the insertion of biopsy needles and needle-like therapeutic instruments directly into millimeter-size tumors, using MR images as feedback. However, magnetic resonance imaging (MRI) systems present a challenging operational environment with high magnetic fields and limited space, making the development of MR-compatible robots difficult. In this paper, we present design requirement analysis and a novel prototype design for an MRIguided biopsy needle manipulator and an MR-compatible transmission that provides sufficient driving forces for needle manipulation inside an MR scanner. The actuators of the manipulator are placed outside the MR room, which are several meters away from the scanner. A combination of a pull-pull cable-sheath and a cable-pulley transmission is used to transmit the actuator force to the manipulator. This configuration can be used to achieve MR-compatibility and leads to the ability to use conventional actuators such as DC motors, which have sufficiently high power to perform needle biopsy. We also studied the feasibility of the proposed transmission and actuation with the proposed manipulator. The accuracy and precision of the needle tip are evaluated and MRcompatibility is verified.