Towards Real-time pose estimation of the Mitral Valve Robot under C-arm X-ray Fluoroscopy

Real-time Pose Tracking for a Continuum Guidewire Robot under Fluoroscopic Imaging

Atherosclerosis is a medical condition that causes buildup of plaque in the blood vessels and narrowing of the arteries. Surgeons often treat this condition through angioplasty with catheter placements. Continuum guidewire robots offer significant advantages for catheter placements due to their dexterity. Tracking these guidewire robots and their surrounding workspace under fluoroscopy in real-time can be useful for visualization and accurate control. This paper discusses algorithms and methods to track the shape and orientation of the guidewire and the surrounding workspaces of phantom vasculatures in real-time under C-arm fluoroscopy. The shape of continuum guidewires is found through a semantic segmentation architecture based on MobileNetv2 with a Tversky loss function to deal with class imbalances. This shape is refined through medial axis filtering and parametric curve fitting to quantitatively describe the guidewire's pose. Using a constant curvature assumption for the guidewire's bending segments, the parameters that describe the joint variables are estimated in real-time for a tendon-actuated COaxially Aligned STeerable (COAST) guidewire robot and tracked through its traversal of an aortic bifurcation phantom. The accuracy of the tracking is ~90% and the execution times are within 100ms, and hence this method is deemed suitable for real-time tracking.

Towards the Design and Development of a Robotic Transcatheter Delivery System for Mitral Valve Implant

Minimally-invasive surgeries using transcatheter approaches and sophisticated imaging modalities are gaining popularity to treat mitral regurgitation (MR). This paper proposes the next generation of a robotic catheter to deliver an implant onto the mitral valve (MV) through a transseptal approach. The proposed robot has an outer diameter (OD) of 5.7 mm, a rigid distal end length of 20 mm, a prismatic tube that can be advanced by 50-60 mm, and a bending joint that can easily bend 120° to reach the valve opening. The implant can be rotated 75° bidirectionally by the distal torsion joint to orient it with the MV leaflet for precise implantation. The robotic joints are modeled individually, the forward and inverse kinematics are derived, and the robot motion validation is carried out through experimentation. A modified kinematics (MK) model, Prandtl-Ishlinskii (PI) hysteresis model, and hybrid of MK and PI model are used to compensate for the catheter nonlinearities. A preliminary study is conducted to evaluate if force sensing can be used to compensate for the effects of fluid flow. Also, the implantation procedure is demonstrated in a phantom heart.