  This paper presents a method of navigating a surgical robot beyond the
resolution of magnetic resonance imaging (MRI) by using a resolution
enhancement technique enabled by high-precision piezoelectric actuation. The
surgical robot was specifically designed for injecting stem cells into the
spinal cord. This particular therapy can be performed in a shorter time by
using a MRI-compatible robotic platform than by using a manual needle
positioning platform. Imaging resolution of fiducial markers attached to the
needle guide tubing was enhanced by reconstructing a high-resolution image from
multiple images with sub-pixel movements of the robot. The parallel-plane
direct-drive needle positioning mechanism positioned the needle guide with a
high spatial precision that is two orders of magnitude higher than typical MRI
resolution up to 1 mm. Reconstructed resolution enhanced images were used to
navigate the robot precisely that would not have been possible by using
standard MRI. Experiments were conducted to verify the effectiveness of the
proposed enhanced-resolution image-guided intervention.
