Abstract
To support needle placements, we developed a compact surgical manipulator system using MRI (magnetic resonance imaging)-guided navigation. The manipulator is designed for use in 430-mm high spaces and the strong magnetic field of an open-MRI. The design uses ultrasonic motors, which are located 750mm away from joints of the manipulator at the center of the MRI. The manipulator can position a puncture needle on the body and pivot around the insertion point to orient the needle. Navigation is performed using MR images of the needle held by the manipulator. While watching these navigational images, the surgeon can maneuver the manipulator to line up the needle trajectory with target, and then manually insert the needle into the target.
The effectiveness of the system was verified with an in-vivo experiment in the MRI (AIRIS-II: Hitachi Medical Corp.). No noticeable deformation in the MR images was observed, even when the manipulator was in motion. Furthermore, the MR images always showed the needle that was moved by the manipulator. This indicates that the manipulator system is accurate enough for needle placement.
