Basket Catheter Tracking With Coaxial Dual-Sensor Shape Estimation
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Solution Overview
Problem
Existing magnetic-based tracking technologies for catheters, such as the ACL technology, face accuracy issues in determining the position and orientation of basket catheters due to nonlinear magnetic field measurements, leading to inaccuracies in predicting the shape of flexible strips and electrode positions.
Innovation Solution
A system using two coil-based position sensors on a catheter, with one sensor at the distal end and another on a pusher, computes location and orientation coordinates iteratively, assuming coaxial alignment, and accounts for distortions to enhance accuracy, allowing for precise estimation of flexible strip positions and electrode locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic-based tracking technology is used to determine catheter position, then location sensing is achieved, but measurement precision deteriorates due to nonlinear magnetic field measurements
Solution Approach 1:
The catheter is divided into multiple segments with individual position sensors at different locations (distal end, proxal end, and intermediate positions). Each sensor independently measures magnetic field position, and the segments are tracked separately to compute the overall catheter configuration, breaking down the complex nonlinear measurement problem into manageable segmental calculations
Solution Approach 2:
A computational intermediary system processes the nonlinear magnetic field measurements from multiple sensors. The system uses iterative algorithms and constraint-based computations (such as maintaining fixed distance relationships between sensors) to transform raw magnetic field data into accurate three-dimensional position and orientation information, mediating between the imperfect magnetic measurements and the required precision
2Measurement precision
If two coil-based position sensors are used with iterative computation, then position measurement accuracy improves to 0.1 mm, but device complexity increases
Solution Approach 1:
Multiple coil-based position sensors are merged into a coordinated measurement system where sensors at different catheter locations work together. The sensors are combined with a unified computational framework that processes their readings simultaneously, using the known geometric relationships between sensor positions to achieve higher accuracy through collaborative measurement rather than isolated sensing
Solution Approach 2:
The system changes the measurement parameters by using multiple sensors at different spatial locations along the catheter rather than a single sensor. By varying the spatial distribution of sensors and using iterative computation with multiple passes, the system transforms the measurement process to achieve sub-millimeter accuracy while managing complexity through systematic parameter optimization
3Adaptability or versatility
If flexible strips are used in expandable assembly, then adaptability improves for vessel engagement, but measurement precision worsens due to shape distortion
Solution Approach 1:
The catheter system transitions from a static rigid structure to a dynamic flexible configuration. The expandable assembly with flexible strips can dynamically adapt its shape to match the vessel geometry, while position sensors continuously track the changing positions. The system computes the dynamic configuration by referencing the known relationships between sensors and flexible strip positions, maintaining measurement accuracy despite continuous shape changes
Solution Approach 2:
The system implements feedback by continuously monitoring the positions of multiple sensors on the flexible catheter and using this information to compute and correct for shape distortions. The known geometric relationships between sensors and flexible strip positions serve as feedback constraints, allowing the system to determine the actual configuration of flexible components even when they deform from their nominal positions
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
Improves position measurement accuracy from 1 mm to 0.1 mm by interdependent and iterative computation, providing accurate visualization of the catheter and body-part anatomy, even in cases of distortion.
Implementation Method 1
A magnetic field sensor within the distal end of the probe generates electrical signals in response to these magnetic fields
Implementation Method 2
at least one magnetic field radiator configured to transmit alternating magnetic fields into a region where the body-part is located
Data Source
AI summary
In one embodiment, a system includes a catheter including an insertion tube and a first position sensor, a pusher including a second position sensor, and an expandable assembly including flexible strips disposed circumferentially around a distal portion of the pusher, with first ends of the strips connected to the distal end of the insertion tube and second ends of the strips connected to the distal portion of the pusher, the flexible strips bowing radially outward when the pusher is retracted, processing circuitry to receive a respective position signal from the first and second position sensors, compute location and orientation coordinates for the position sensors subject to a constraint that the position sensors are coaxial and have a same orientation, compute a distance between the computed location coordinates of the position sensors, and find position coordinates of the flexible strips responsively to at least the computed distance.