Intra-body Probe Wall Proximity Imaging via Impedance Mapping
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Solution Overview
Problem
Current imaging methods within body cavities using intra-body devices struggle to accurately estimate the proximity of intra-body lumen walls to electrodes, particularly in minimally invasive structural heart disease interventions, due to limitations in sensing electrical fields and impedance measurements.
Innovation Solution
A method involving the generation of an electrical field by transmitting current from a first electrode to a ground electrode, measuring voltage differences between electrodes, calculating local impedance, and converting it to estimate wall proximity, with sensitivity functions applied to map the shape of the lumen walls in three-dimensional space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical field sensing and impedance measurement are used to estimate wall proximity, then imaging capability within body cavities is enabled, but measurement precision of wall distance is insufficient
Solution Approach 1:
The patent divides the measurement function into multiple specialized electrodes: a first electrode for current transmission, a second electrode for voltage sensing, and a third electrode as ground reference. This segmentation allows each electrode to be optimized for its specific function, improving the precision of impedance measurements and wall proximity estimation compared to using a single electrode for all functions.
Solution Approach 2:
The patent introduces an intermediary computational process that converts raw impedance measurements into wall proximity estimates using sensitivity functions. These sensitivity functions act as mathematical intermediaries that translate electrical measurements into accurate spatial information, resolving the difficulty of directly measuring wall distance from electrical fields.
2Measurement precision
If multiple electrodes are used for electrical field generation and sensing, then wall proximity measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent designs the multi-electrode probe where electrodes serve multiple functions: the first electrode transmits current and can also sense voltage, the second electrode senses voltage and can transmit current, and the third electrode serves as both ground reference and current path. This multi-functionality reduces the need for additional specialized components, managing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent implements self-service through automatic calibration and sensitivity function determination. The system performs self-calibration by measuring impedance at known distances during manufacturing or initial use, automatically generating the sensitivity functions needed for accurate wall proximity estimation. This eliminates the need for complex manual calibration procedures and reduces operational complexity.
3Power
If current is transmitted from first electrode to ground electrode, then electrical field generation is achieved, but current may inadvertently flow through second electrode reducing measurement accuracy
Solution Approach 1:
The patent maintains equipotentiality by carefully designing the electrical field configuration where the ground electrode is positioned to create a reference potential that minimizes unwanted current paths. The sensitivity functions are specifically calibrated to account for the geometric arrangement of electrodes, ensuring that voltage measurements at the second electrode accurately reflect the electrical field generated by the first electrode without contamination from stray current flow.
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 enables precise estimation of wall proximity and shape within body lumens, enhancing imaging accuracy for catheterization procedures by effectively using electrical fields to determine wall positions and shapes, even at close distances.
Implementation Method 1
generating an electrical field by transmitting a current from the first electrode to a ground electrode
Implementation Method 2
measuring a voltage difference of the electrical field between the first electrode and a second electrode
Implementation Method 3
calculating a measure of local impedance for a region around the first electrode, using: the voltage difference measured between the first and second electrodes and a measurement of the current between the first electrode and the ground
Data Source
AI summary
Methods and apparatuses for imaging an intra-body object. An exemplary method includes: measuring electrical measurements using electrodes of a probe hovering inside a body lumen; identifying, based on said electrical measurements, a volume encompassing the electrodes used for the measurements as a volume free of any lumen wall; and inferring, from the identified volume free of any lumen wall, a wall in the vicinity of the probe, thereby imaging at least a portion of the object.