MRI Catheter Coil Steering to Reduce Heating and Image Distortion
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Solution Overview
Problem
Existing MRI-guided catheter designs face challenges with image distortion, weight, bulkiness, and heating issues due to embedded magnetic elements, limiting their effectiveness in navigating narrow vessels and ensuring safe tissue interaction.
Innovation Solution
A catheter design with a set of coils, including four side coils and an axial coil, arranged to generate controlled Lorentz forces for steering, optimized using a Cosserat model to minimize torque and current, mitigating heating through a heat-mitigated strategy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If magnetic elements are embedded in the catheter for MRI-driven actuation, then steering capability and response time are improved, but image distortion and device weight increase
Solution Approach 1:
The patent removes permanent magnets from the catheter design and replaces them with electromagnetic coils that generate magnetic fields only when activated. This extraction of permanent magnetic elements eliminates continuous image distortion while maintaining the ability to generate magnetic fields for actuation only when needed, thus resolving the contradiction between steering capability and image quality.
Solution Approach 2:
The catheter uses periodic activation of electromagnetic coils rather than continuous magnetic field generation. The coils are activated only during steering maneuvers and deactivated otherwise, creating a periodic action pattern. This approach maintains fast response time when actuation is needed while minimizing overall image distortion during non-actuation periods.
2Force
If microcoils are used for Lorentz force-based steering, then force-to-weight ratio is improved, but Joule heating effects increase
Solution Approach 1:
The patent implements dynamic control of coil activation based on real-time feedback from motion tracking and navigation systems. Coils are activated only when and where needed during the procedure, rather than continuously. This dynamic approach maintains high force-to-weight ratio during actuation while minimizing cumulative Joule heating effects by reducing overall activation time and duration.
Solution Approach 2:
The system incorporates feedback mechanisms that monitor catheter position, orientation, and thermal conditions to dynamically adjust coil activation patterns. When thermal thresholds are approached or navigation can be achieved through passive tracking, coil activation is reduced or paused, allowing thermal dissipation while maintaining navigation capability through feedback-driven control.
3Ease of operation
If active catheter design with force transmission mechanisms is used, then maneuverability is improved, but device complexity and stiffness variability increase
Solution Approach 1:
The patent replaces complex mechanical force transmission mechanisms (tendons, hydraulics, pneumatics) with a magnetic field-based actuation system. Electromagnetic coils generate Lorentz forces directly in response to external MRI gradient fields, eliminating the need for mechanical force transmission components. This substitution reduces device complexity while maintaining maneuverability through direct magnetic actuation.
Solution Approach 2:
The catheter achieves maneuverability changes by varying electrical parameters (current magnitude, pulse duration, activation pattern) rather than mechanical parameters. By changing electrical input parameters to the coils, the system can dynamically adjust force magnitude and direction without mechanical reconfiguration, simplifying the overall device architecture while maintaining ease of operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise, compact, and safe navigation within narrow vasculature by minimizing Joule heating and image distortion, enhancing maneuverability and safety in MRI environments.
Implementation Method 1
mounting microcoils on the catheter tip for Lorentz force-based catheter steering
Implementation Method 2
MRI-driven actuation can utilize imaging gradient coils user-controlled to generate spatial field gradients for steering
Implementation Method 3
microcoil-based Joule heating effects have been a major design concern
Data Source
AI summary
A catheter and a method for controlling the catheter, wherein the catheter has a tip, optionally comprising a working channel extending through the tip of the catheter, a set of coils surrounding the tip, and power wires arranged to supply the set of coils with electrical energy, wherein the set of coils comprises four side coils arranged around the tip such that a straight line standing orthogonal on a longitudinal direction of the tip crosses a center of the respective side coil.