Six degrees of freedom robotic arm to guide high intensity focused ultrasound therapy for atherosclerotic plaques

Background: In the search for novel treatment options for
atherosclerosis, high intensity focused ultrasound (HIFU)
has shown promising results in terms of feasibility and
acute safety. HIFU is non-invasive and can produce precisely
located millimeter thermal lesions with little or no
damage to surrounding tissue. To ensure continuous lesion
formation within plaques, subsequent discrete HIFU shots
need to be delivered for multiple transverse planes in direction
of the target vessel. To evolve HIFU to a standard
treatment modality for atherosclerosis, precise localization
and targeting of atherosclerotic plaques is required. We
have investigated the feasibility of using the robotic arm to
guide HIFU therapy.
Methods: The HIFU transducer was attached to a six
degrees-of-freedom UR3 robot (Universal Robots). The
robot was linked to MATLAB (MathWorks) software to
allow submillimeter movement in any direction. In three
pigs (50 kg), 6–8 HIFU shots were delivered to the dorsal
wall of the femoral artery, in 25–35 transverse planes
spaced 1 mm apart. All 3D ablation positions were saved
and visualized in real-time. The 3D distance to the previous
ablation position was displayed to allow precise spacing
between subsequent ablations and ensure a continuous
lesion.
Results: We were able to accurately control HIFU
transducer motion using the robotic setup. The HIFU transducer
could be moved and rotated in all three orthogonal
directions, with respect to either the skin or the HIFU
focus.
Conclusions: The feasibility of robotic HIFU transducer
control during noninvasive HIFU surgery for atherosclerotic
plaque targeting was demonstrated, along with realtime
visualization of the ablation positions