Multipoint Dixon MR Spectral Component Separation
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Solution Overview
Problem
Current magnetic resonance (MR) measurement techniques require a large number of MR signals at multiple echo times to achieve precise separation of spectral components, leading to extended measurement durations.
Innovation Solution
A method using a multipoint Dixon technique with a bipolar multi-echo MR measurement sequence at three echo times, incorporating a spectral model that accounts for relaxation rates and eddy current effects, allows for the precise determination of spectral components with reduced measurement time by alternately using positive and negative readout gradient fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a relatively complex spectral model is used to determine spectral components precisely, then measurement precision is improved, but measurement duration is extended
Solution Approach 1:
The patent applies parameter changes by modifying the spectral model to incorporate eddy current phase effects and using bipolar gradient fields. This allows the system to achieve precise spectral component determination with fewer echo times by changing the physical parameters of the measurement sequence rather than increasing the number of measurements
Solution Approach 2:
The patent replaces the traditional approach of acquiring many MR signals with a bipolar multi-echo sequence. By substituting the mechanical acquisition process with a modified spectral model that accounts for eddy current effects, the system achieves precise measurements without extending measurement duration
2Measurement precision
If multiple MR signals are acquired at different echo times to separate spectral components, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the measurement process into a bipolar multi-echo sequence with alternating gradient polarities. By dividing the gradient application into distinct positive and negative phases, the system simplifies the overall measurement complexity while maintaining precise spectral component separation
Solution Approach 2:
The patent employs periodic action through the alternating bipolar gradient fields in the multi-echo sequence. The regular alternation between positive and negative gradients creates a predictable pattern that simplifies the measurement process while enabling precise spectral decomposition
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 accurate determination of spectral components, such as fat and water, with reduced measurement duration and low signal noise, facilitating efficient clinical diagnostics.
Implementation Method 1
a predetermined spectral model of the multipoint Dixon technique includes at least the at least two spectral components with respective associated relaxation rates, a first phase due to field inhomogeneities, and a second phase due to eddy current effects
Implementation Method 2
The chemical shift between hydrogen nuclear spins in water as a first spectral component, and hydrogen nuclear spins in fatty acid chains as a second spectral component, is often used
Implementation Method 3
The different spectral components have different phase positions at the different echo times. Using this effect, it is possible to determine the different spectral components separately
Data Source
AI summary
In a method and magnetic resonance (MR) apparatus to acquire MR data from a subject, a predetermined spectral model of a multipoint Dixon technique is used that includes at least two spectral components with respective associated relaxation rates, a first phase due to field inhomogeneities; and a second phase due to eddy current effects. MR data are acquired using a bipolar multi-echo MR measurement sequence for multiple image points wherein, for each image point, the multi-echo MR measurement sequence alternately uses positive and negative readout gradient fields for the readout of MR signals of the MR data at at least three echo times. The at least two spectral components are determined based on the MR data.