Local Maxwell Tomography for Noninvasive Electrical Property Mapping
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Solution Overview
Problem
Current methods for noninvasive electrical property mapping of tissues and materials face challenges such as ill-conditioned inverse problems, limited spatial resolution, and inaccuracies due to the lack of access to absolute RF phase, particularly at high field strengths, which affect the accuracy of electrical property estimation and MR image quality.
Innovation Solution
The Local Maxwell Tomography (LMT) technique uses measurements of magnetic field curvature from arrays of RF transmitter and detector coils to determine electrical properties without symmetry assumptions, employing complementary information from transmit and receive sensitivity distributions to resolve ambiguities and achieve accurate mapping of conductivity and permittivity at arbitrary field strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If EPT technique uses birdcage coil design with symmetry assumptions to achieve noninvasive electrical property mapping, then the technique can circumvent limitations of surface-based inverse problems, but the assumptions fail at high field strength where field curvature is greatest, leading to errors in property estimation
Solution Approach 1:
The patent abandons the symmetric birdcage coil design and its associated symmetry assumptions. Instead, it uses arbitrary coil configurations without requiring any symmetry conditions, allowing the method to remain valid at high field strengths where field curvature breaks symmetry assumptions.
Solution Approach 2:
The patent changes the fundamental parameters of the approach by using a fully general formulation that does not rely on symmetry constraints. The method solves the complete system of equations for arbitrary coil geometries and field strengths, rather than making approximations valid only under symmetric conditions.
2Ease of operation
If surface-based electrical prospection techniques are used to map electrical properties, then noninvasive measurement is achieved, but the inverse problem is inherently ill-conditioned, leading to fundamental challenges of robustness and spatial resolution
Solution Approach 1:
The patent uses MRI-measured field amplitudes and phases as intermediary quantities that provide direct information about interior electromagnetic fields. This intermediary measurement approach bypasses the ill-conditioned surface-based inverse problem by using internal field information to constrain the solution.
Solution Approach 2:
The patent replaces the mechanical surface-based measurement system with an electromagnetic field-based approach using MRI. Instead of relying on surface potential measurements, the method uses measured interior field distributions to directly infer electrical properties, substituting one measurement paradigm for another more informative one.
3Ease of operation
If MRI is used as a probe of internal distribution of currents and magnetic fields to enable new impedance mapping techniques, then noninvasive mapping without injected currents is achieved, but MRI provides only partial information about interior currents and fields, limiting accuracy
Solution Approach 1:
The patent uses measured field amplitudes and phases from MRI as feedback to constrain the inverse problem solution. The measured quantities provide direct constraints on the interior field distributions, reducing the ambiguity and information loss inherent in partial measurements.
Solution Approach 2:
The patent makes the MRI-measured quantities serve multiple functions: they provide both the field amplitude information and the phase information needed to solve for electrical properties. The same measurement data is used to constrain both the magnitude and phase aspects of the interior field distributions.
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
LMT provides robust and accurate noncontact mapping of electrical permittivity and conductivity, eliminating errors associated with rapid field variation and allowing for electrical property mapping across a wide range of coil designs and field strengths, thereby improving the quality and reliability of MR images.
Implementation Method 1
applying a plurality of stimulations to the at least one target... generating an electromagnetic field
Implementation Method 2
receiving at least one signal from the at least one target in response to the applied stimulations
Implementation Method 3
supplying the electromagnetic-field-related quantities to a system of equations relating these quantities to a plurality of electrical property values
Data Source
AI summary
Apparatus, method, and computer-accessible medium embodiments for a noninvasive mapping of electrical properties of tissues or materials. For example, it is possible to apply a plurality of stimulations to a target. It is possible to receive at least one signal from the target in response to the applied stimulations. Further, it is possible to process the at least one signal to determine electromagnetic-field-related quantities associated with the stimulations and the target response. Also, it is possible to supply the electromagnetic-field-related quantities to a system of equations relating these quantities to a plurality of electrical property values and residual field-related unknown values of the at least one target. It is also possible to determine a solution to the system of equations, including determining at least one electrical property of the at least one target.