Electrical Properties Tomography Artefact Reduction
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Solution Overview
Problem
The Transceive Phase Assumption (TPA) in electrical properties tomography (EPT) becomes increasingly invalid with higher main static magnetic fields (B0) and larger object sizes, leading to artefacts in electrical properties maps.
Innovation Solution
A system and method for electrical properties tomography that involves acquiring magnetic resonance imaging data from an object in two positions, typically 180 degrees apart, and constructing and registering maps of electrical properties from each position to reduce artefacts and improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the Transceive Phase Assumption (TPA) is used to estimate B1 transmit field from B1 transceive phase, then the measurement process is simplified, but measurement precision deteriorates progressively with increasing main static magnetic field B0 and/or increasing object size
Solution Approach 1:
The patent segments the B1 phase measurement into two separate components: B1 transmit phase and B1 receive phase. By acquiring data at two different positions (e.g., head-first and feet-first orientations) and separating the transmit and receive phase contributions, the method eliminates the need for the TPA approximation while maintaining operational feasibility.
Solution Approach 2:
The patent introduces a spatial dimension by acquiring measurements at two different object positions/orientations. This additional spatial sampling dimension enables the separation of transmit and receive phase components, transforming the single-position measurement limitation into a multi-position measurement advantage that resolves the phase ambiguity.
2Manufacturing precision
If measurements are acquired at two different positions and maps are registered and averaged, then artefacts in electrical properties maps are reduced, but measurement time and processing complexity increase
Solution Approach 1:
The patent performs preliminary registration of the two B1 magnitude maps before averaging the electrical properties maps. By pre-aligning the anatomical structures through registration using anatomical marks or regions, the method ensures that corresponding voxels are averaged together, preventing misregistration artefacts and enabling accurate artefact reduction.
Solution Approach 2:
The patent creates a copy of the first B1 magnitude map and registers it to the second position. This registered copy is then used to guide the averaging process of the electrical properties maps, ensuring that the artefact reduction is performed on correctly aligned anatomical structures rather than raw unregistered data.
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
The proposed solution significantly reduces artefacts in electrical properties maps, enhancing the accuracy of EPT results, especially at higher magnetic field strengths and for larger objects without axial symmetry.
Implementation Method 1
electrical properties tomography (EPT) is an imaging method that uses a magnetic resonance (MR) system to non-invasively derive the spatial distribution of the conductivity σ and permittivity ε
Implementation Method 2
measurement of magnitude and phase of the radiofrequency (RF) transmit field B1
Data Source
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AI summary
Methods and systems for electric properties tomography imaging are presented. Maps of electrical properties such as conductivity and permittivity maps of an object are constructed with improved accuracy, in particular for objects having shapes with insufficient axial symmetry, thereby correcting for shortcoming caused by Transceive Phase Assumption in electric properties tomography.