Magnetic Resonance Control Parameter Selection
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Solution Overview
Problem
Conventional methods for determining control parameters for magnetic resonance devices are time-consuming and prone to numerical uncertainties, particularly in measuring B1 maps and optimizing excitation sequences, which can extend examination duration and complicate monitoring of SAR.
Innovation Solution
A method that selects a set of control parameters based on determining a mean flip angle using a simpler, non-spatially resolved measurement approach, reducing the solution space to predefined parameter settings, and choosing parameters that maximize or minimize signal strength, allowing for quicker adjustment and less sensitivity to measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional B1 map measurement and optimization methods are used to determine control parameters, then the excitation homogeneity is improved, but the examination time is significantly extended
Solution Approach 1:
The patent segments the parameter optimization process by dividing the control parameters into different groups (first group and second group) that can be optimized independently and sequentially. This allows the system to achieve good excitation homogeneity without requiring complete optimization of all parameters simultaneously, thereby reducing the overall measurement and optimization time.
Solution Approach 2:
The patent applies preliminary action by performing a preliminary optimization of the first group of control parameters before finalizing the complete parameter set. This preliminary optimization establishes a good initial state that reduces the complexity and time required for subsequent optimization steps, avoiding the need for time-consuming complete re-optimization.
2Manufacturing precision
If numerical optimization algorithms are used to determine control sequences, then the excitation quality is improved, but numerical uncertainties and measurement errors increase
Solution Approach 1:
The patent segments the optimization process into multiple stages with different objective functions. The first stage optimizes for excitation homogeneity using a first objective function, and the second stage refines the solution using a second objective function. This segmentation reduces numerical uncertainties by breaking down the complex optimization problem into more manageable sub-problems with fewer iterative calculations.
Solution Approach 2:
The patent implements feedback by using the results from the first optimization stage as input for the second optimization stage. The measured signal intensities and calculated flip angle distributions from the first stage provide feedback that guides the second optimization, reducing sensitivity to measurement errors and improving overall reliability.
3Manufacturing precision
If patient-specific B1 maps are measured for adjustment, then the flip angle distribution homogeneity is improved, but the measurement complexity and time are increased
Solution Approach 1:
The patent segments the parameter groups into two categories: first group parameters that have strong influence on excitation homogeneity and are optimized using patient-specific measurements, and second group parameters that are optimized using more general approaches. This segmentation reduces measurement complexity by focusing detailed patient-specific measurements only on the most critical parameters.
Solution Approach 2:
The patent applies partial action by measuring and optimizing only the most critical control parameters using patient-specific B1 maps, rather than performing complete optimization of all parameters. This partial optimization achieves sufficient excitation homogeneity while significantly reducing measurement complexity and time requirements.
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 method significantly reduces examination time, enhances the homogeneity of flip angle distribution, and increases the robustness of signal strength, making it less sensitive to physiological movements and measurement errors, while allowing for automatic operation of the magnetic resonance device.
Implementation Method 1
the spins of the layer are excited, and the decay, for example, in this excitation is observed as a signal
Implementation Method 2
the spins of resonantly excited nuclei, spatially resolved by the gradients, are tilted by a flip angle with respect to the magnetic field lines of the basic magnetic field
Data Source
AI summary
A method for determining a set of control parameters of a control sequence for a magnetic resonance device is provided. The set of control parameters is chosen from a plurality of sets of basic parameters. The method includes determining a mean flip angle for each set of basic parameters in an imaging region where an object exists using the set of basic parameters with a first measuring method. For each set of basic parameters, a signal strength of a magnetic resonance signal generated in the case of a reference flip angle of a second measuring method distinguished by a signal maximum or a signal minimum is determined, and the set of basic parameters having a signal strength that is extremal in accordance with the choice of reference flip angle is chosen as the set of control parameters.