MR Flow Measurement Parameter Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing MR phase contrast flow measurements suffer from significant errors due to eddy current and dephasing effects, particularly at high flow velocities or large local velocity changes, and rely on a single flow protocol for all applications, leading to varying precision in measured flow values.
Innovation Solution
A method to automatically determine optimal parameters for phase contrast flow measurements by performing pre-measurements with varying parameter sets, analyzing phase values to create a model that minimizes phase errors, including eddy current and dephasing errors, and adapting these models for arbitrary parameter sets to identify the parameter set with the smallest phase error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gradient strengths and rise times are reduced to minimize eddy currents, then eddy current errors decrease, but measurement sequence duration (echo time TE) increases
Solution Approach 1:
The patent applies parameter changes by systematically varying gradient strengths, rise times, and echo times across multiple pre-measurements to identify the optimal parameter set that minimizes phase errors while maintaining acceptable measurement duration. This is evident in the flowchart showing iterative adjustment of parameters G1, G2, TR, and TE to find the best compromise between error reduction and time efficiency.
2Measurement precision
If echo time TE is minimized to reduce intravoxel dephasing, then dephasing errors decrease, but eddy current effects increase
Solution Approach 1:
The patent resolves this contradiction by changing multiple parameters simultaneously rather than optimizing a single parameter in isolation. The method varies gradient strengths, rise times, and echo times together to find a parameter combination that balances both eddy current effects and intravoxel dephasing, achieving overall minimization of phase errors.
Solution Approach 2:
The patent employs dynamics by adaptively selecting measurement parameters based on the specific application scenario. Rather than using fixed parameters, the system dynamically adjusts gradient strengths, rise times, and echo times according to the measured flow characteristics and error analysis from pre-measurements.
3Device complexity
If a single flow protocol is used for all applications, then device complexity is reduced, but measurement precision varies across different scenarios
Solution Approach 1:
The patent implements self-service by enabling the measurement system to automatically determine and optimize its own parameters through pre-measurements and error analysis. The system performs self-characterization of eddy current effects and intravoxel dephasing, then autonomously selects the optimal parameter set without requiring user intervention or multiple pre-configured protocols.
Solution Approach 2:
The patent makes the measurement system dynamic by allowing parameters to be adapted based on the specific measurement scenario. The system transitions from static, pre-defined protocols to dynamic parameter selection based on real-time error analysis and flow characteristics.
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 optimizes the measurement sequence by minimizing both eddy current and intravoxel dephasing errors, enabling precise flow measurements across different scenarios and parameter sets, improving the accuracy and reliability of phase contrast flow measurements.
Implementation Method 1
a flow coding sequence with varied parameters is used for an MR phase contrast pre-measurement
Implementation Method 2
phase values of the pre-measurement are analyzed in order to adapt a model with which an extent of a phase error can be determined
Implementation Method 3
The two most important sources of errors are remaining eddy current effects and dephasing errors
Implementation Method 4
dephasing errors that lead to signal cancellations due to an intravoxel dephasing (due to the spin-spin interaction, for example), particularly at high flow velocities
Data Source
AI summary
In a method and a magnetic resonance system to automatically determine parameters of a phase contrast flow measurement, a phase contrast pre-measurement with a flow coding sequence is implemented in a predetermined volume segment of an examination subject, and the flow coding sequence is varied in terms of its parameters so that a pre-measurement is respectively implemented for multiple different parameter sets of the flow coding sequence. A model is automatically determined with which a dimension of a phase error can be determined for each parameter set in the flow measurement, in that phase values of the pre-measurement which is implemented with the flow coding sequence with the respective parameter set are analyzed. Those parameters of the flow measurement at which the dimension of the phase error is smallest are automatically determined.