Multi-Echo MR Image Reconstruction via Segmented Signal Models
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Solution Overview
Problem
Current techniques for determining magnetic resonance images with multiple spin species using chemical shift imaging multi-echo MR measurement sequences face challenges in achieving a balance between precision and speed, often resulting in either imprecise quantification due to simplifications or increased measurement time leading to movement artifacts.
Innovation Solution
A method involving the acquisition of a predetermined number of MR signals using a multi-echo MR measurement sequence, followed by the determination of two approximated MR images based on different approximative models that consider varying MR parameters, with a mean calculation to produce a final MR image, allowing for fast and precise determination of spin species content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If comprehensive signal models considering multiple MR parameters (T2*, multispectral fat) are used, then measurement precision is improved, but measurement time increases leading to movement artifacts
Solution Approach 1:
The patent segments the comprehensive signal model into multiple approximative models, each considering only a subset of MR parameters (e.g., one model considers T2* but simplifies fat spectrum, another considers multispectral fat but simplifies T2*). This allows parallel or sequential processing of simpler models to achieve comprehensive results without the full computational burden of a single comprehensive model, reducing measurement time while maintaining precision.
Solution Approach 2:
The patent applies partial action by using approximative models that consider only partial aspects of the full signal model (either T2* effects or multispectral fat, but not both in full detail simultaneously). This partial consideration of parameters in separate models allows faster processing while the combination of results achieves comprehensive accuracy.
2Measurement precision
If additional MR parameters (T2*, multispectral fat) are considered in signal analysis, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the complex signal analysis into multiple simpler approximative models, each handling a specific subset of parameters. This segmentation reduces the computational complexity of individual models while maintaining overall precision through the combination of their results.
Solution Approach 2:
The patent changes the parameter considerations across different approximative models - each model uses a simplified set of parameters compared to the comprehensive model. By varying which parameters are considered in each model, the overall system achieves comprehensive accuracy while individual models remain computationally simple.
3Measurement precision
If more MR signals are acquired to improve precision, then measurement precision is improved, but measurement time increases
Solution Approach 1:
The patent uses a predetermined number of MR signals (not necessarily the maximum needed for full precision) and processes them through multiple approximative models. This partial acquisition combined with multiple processing approaches achieves stable solutions without requiring excessive measurement time for additional signals.
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 a rapid and accurate determination of MR images with minimal movement artifacts, allowing for flexible adaptation to breathing cycles and reduced measurement time, while maintaining precision in fat and water quantification and T2* estimation.
Implementation Method 1
Such techniques make use of the effect that the resonance frequency of the nuclear spins depends on the molecular or chemical environment. This is known as a chemical shift.
Implementation Method 2
Chemical shift imaging multi-echo magnetic resonance (MR) measurement sequences
Implementation Method 3
an estimate can also be obtained for the T2* relaxation time that manifests in an echo time-dependent reduction of the signal strength
Data Source
AI summary
In a method and apparatus to determine a magnetic resonance image of an examination subject with at least two spin species by using a chemical shift imaging multi-echo MR measurement sequence, first approximated MR image is determined based on a first approximative model and of a second approximated MR image is determined based on a second approximative model, wherein the first and second approximative model respectively express an MR signal under consideration of one or more MR parameters, and wherein the first and second approximative model differ with regard to the consideration of at least one MR parameter. The MR image is determined from a mean calculation that depends on the first and second approximated MR image.