Catheter Electrode Localization via Magnetic and Impedance Fusion
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Solution Overview
Problem
Existing medical device positioning systems face challenges in accurately locating electrodes within a patient reference frame due to impedance shifts, drifts, and instability, particularly when relying primarily on impedance-based measurements, which can lead to distorted and unstable representations of catheter positions, and fail to account for patient movement and device shape changes.
Innovation Solution
A system that integrates impedance and magnetic sensor measurements to estimate the latent state of a medical device within a patient reference frame, using a composite model that predicts and updates electrode locations based on both predicted and measured responses, thereby enhancing accuracy and stability without relying on direct transformation between impedance and magnetic coordinate systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If impedance-based positioning system is used to locate multiple electrodes, then the ability to simultaneously locate a large number of sensors is improved, but measurement accuracy deteriorates due to electrical interference and impedance shifts
Solution Approach 1:
The patent combines impedance-based positioning system and magnetic field-based positioning system into a unified coordinate system through registration processes. This allows the system to simultaneously track multiple electrodes using impedance while using magnetic sensors for accurate reference point tracking, thereby maintaining both high sensor quantity capability and measurement precision.
Solution Approach 2:
The patent introduces a coordinate system registration mechanism as an intermediary that transforms impedance measurements into the magnetic field-based coordinate system. This mediator allows impedance data to be interpreted within a more stable reference frame, improving measurement accuracy while preserving the ability to track multiple sensors.
2Measurement precision
If magnetic field-based positioning system is used to improve accuracy, then measurement precision is improved, but the number of locatable sensors is reduced
Solution Approach 1:
The patent creates a unified positioning system that serves multiple functions: it can track both impedance-based electrodes and magnetic sensors within the same coordinate framework. This multi-functional approach allows the system to maintain high measurement precision for critical points using magnetic sensors while simultaneously tracking additional electrodes through impedance measurements.
3Measurement precision
If coordinate system registration is performed between impedance and magnetic systems, then measurement accuracy is improved, but system complexity increases
Solution Approach 1:
The patent performs coordinate system registration in advance by placing fiducial markers that are detectable by both impedance and magnetic systems. This preliminary action establishes the transformation relationship between the two coordinate systems before actual measurements begin, simplifying subsequent positioning operations.
Solution Approach 2:
The patent uses fiducial markers as physical copies that exist in both coordinate systems simultaneously. These markers create a bridge between impedance and magnetic coordinate frames, allowing the system to determine transformation parameters without complex real-time calculations.
4Measurement precision
If fiducial pairs are used for coordinate transformation, then electrode positioning accuracy is improved, but device complexity increases due to co-location requirements
Solution Approach 1:
The patent extracts the coordinate transformation function from the main positioning system by using separate fiducial markers. These markers handle the registration task independently, allowing the main system to focus on tracking electrodes and magnetic sensors without the complexity of real-time coordinate transformations.
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
This approach provides more accurate and stable location tracking of catheter electrodes by continuously fusing impedance and magnetic measurements, accounting for patient movement and device shape changes, and improving the overall identification of catheter positions in three-dimensional space.
Implementation Method 1
The generators provide a controlled low-strength AC magnetic field in the area of interest (i.e., an anatomical region). The detection coils produce a respective signal indicative of one or more characteristics of the sensed field.
Implementation Method 2
The system can determine P&O by applying a current across pairs of electrodes, measuring respective voltages induced at the device electrodes (i.e., with respect to the reference sensor), and then processing the measured voltages.
Data Source
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Figure 3A~3D
AI summary
Provided herein are systems and methods for use in identifying location of electrodes of a catheter within a three-dimensional space. The systems and methods initially predict locations of physical electrodes and/or physical magnetic sensors of the catheter in the three-dimensional space. Impedance and/or magnetic responses are predicted for the predicted locations. Actual measurements/responses (e.g., measured responses) are then obtained for the physical electrodes and/or physical sensors. Based on the predicted responses and the measured responses, the systems and methods generate calculated locations of electrodes and/or sensors in the three-dimensional space. The systems and method utilize information from both the predicted responses and the measured responses to produce the calculated locations, which may have an accuracy that is greater than locations produced by either the predicted responses or the measured responses.