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. 2016 Oct;44(10):2863-2873.
doi: 10.1007/s10439-016-1585-7. Epub 2016 Mar 16.

A Concentric Tube Continuum Robot With Piezoelectric Actuation for MRI-Guided Closed-Loop Targeting

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Free PMC article

A Concentric Tube Continuum Robot With Piezoelectric Actuation for MRI-Guided Closed-Loop Targeting

Hao Su et al. Ann Biomed Eng. .
Free PMC article

Abstract

This paper presents the design, modeling and experimental evaluation of a magnetic resonance imaging (MRI)-compatible concentric tube continuum robotic system. This system enables MRI-guided deployment of a precurved and steerable concentric tube continuum mechanism, and is suitable for clinical applications where a curved trajectory is needed. This compact 6 degree-of-freedom (DOF) robotic system is piezoelectrically-actuated, and allows simultaneous robot motion and imaging with no visually observable image artifact. The targeting accuracy is evaluated with optical tracking system and gelatin phantom under live MRI-guidance with Root Mean Square (RMS) errors of 1.94 and 2.17 mm respectively. Furthermore, we demonstrate that the robot has kinematic redundancy to reach the same target through different paths. This was evaluated in both free space and MRI-guided gelatin phantom trails, with RMS errors of 0.48 and 0.59 mm respectively. As the first of its kind, MRI-guided targeted concentric tube needle placements with ex vivo porcine liver are demonstrated with 4.64 mm RMS error through closed-loop control of the piezoelectrically-actuated robot.

Keywords: Concentric tube continuum robot; Image-guided surgery; MR-conditional.

Figures

FIGURE 1
FIGURE 1
Illustration of the 3-segment concentric tube continuum manipulator kinematics with the joint variables.
FIGURE 2
FIGURE 2
3D CAD model of the concentric tube manipulator showing Cartesian base stage, needle driver module, fiducial frame, and the 3 concentric tubes.
FIGURE 3
FIGURE 3
The coordinate system and kinematic chain is used to determine the tip location in the RAS coordinates.
FIGURE 4
FIGURE 4
The Z-frame registration fiducial (left) with corresponding cross-sectional MR image (right).
FIGURE 5
FIGURE 5
The optical tracking system for validation of concentric tube robot kinematics and assessment of free space accuracy.
FIGURE 6
FIGURE 6
Free space evaluation of the accuracy of the active cannula robot. The concentric tube robot was moved to 12 desired points (red circles) in free space and the actual position was measured by the optical tracker (blue stars).
FIGURE 7
FIGURE 7
The phantom and robot experimental setup illustrating the concentric tube continuum robot at the entrance of the 3T MRI scanner bore.
FIGURE 8
FIGURE 8
MRI-guided multiple-point targeting results inside a gelatin phantom. The concentric tube robot was closed-loop controlled to move the needle tip to 12 desired points (red circles) in gelatin phantom and the actual position was measured by analyzing acquired MR images (blue stars).
FIGURE 9
FIGURE 9
Simulation of the remote center of motion like kinematics of the concentric continuum robot. Three needle placement trajectories reach the same target point, achieved by applying different configurations of both the Cartesian base and the concentric tubes.
FIGURE 10
FIGURE 10
Overlaid camera images of three actual robot trajectories targeting the same point from multiple approach trajectories.
FIGURE 11
FIGURE 11
MR images of 3 different concentric tube robot needle insertion trajectories to the same target location in the soft gelatin phantom. Closed-loop inverse kinematics was utilized to reach the same target with different joint space configurations.
FIGURE 12
FIGURE 12
Experimental setup for ex vivo tissue evaluation. The interventional robot is inside 3T MRI scanner bore deploying concentric tubes, and the MRI console outside displaying the live MR image of the curved path.
FIGURE 13
FIGURE 13
Volumetric MR image showing a representative active cannula path inserted into a ex vivo liver by the robot inside the MRI scanner. The cannula is inserted along the I-S direction (vertical in this figure) and is shown in the coronal plane along with additional two cross-sectional planes.
FIGURE 14
FIGURE 14
Ex vivo tissue results showing three different selected targets (red spheres) and the corresponding needle trajectory and needle tip location on axial TSE T2 weighted MR images.

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