Magnetic Resonance Control Sequence Direction Adaptation
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Solution Overview
Problem
Magnetic resonance imaging systems face challenges in reducing aliasing artifacts, particularly when a larger field of view is selected, leading to signal cancellations due to chemical shift and sensitivity to B0 inhomogeneities.
Innovation Solution
A method to determine a magnetic resonance control sequence with a first pulse arrangement acting in a spatially selective manner in one direction and a second pulse arrangement acting in an orthogonal direction, allowing for automatic adjustment of selection directions based on the viewing volume's dimensions, optimizing the excitation and refocusing processes to minimize aliasing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a larger field of view is selected to improve coverage, then the viewing volume increases, but aliasing artifacts and signal cancellations due to chemical shift increase
Solution Approach 1:
The patent dynamically determines the first and second selection directions based on the aspect ratio of the viewing volume dimensions. The control sequence determination device automatically adapts the pulse arrangement directions to the specific geometry of the imaging volume, optimizing the balance between field of view coverage and artifact reduction for each imaging scenario.
Solution Approach 2:
The patent changes the selection of spatial directions for pulse arrangements based on the aspect ratio parameter of the viewing volume. By comparing dimensions in different directions and selecting optimal directions for first and second pulse arrangements, the system adjusts critical parameters to minimize aliasing while maintaining the desired field of view.
2Device complexity
If fixed selection directions are used in pulse arrangements, then the sequence design is simplified, but sensitivity to B0 inhomogeneities and chemical shift effects increases
Solution Approach 1:
The system transitions from fixed, predetermined selection directions to dynamic, adaptive selection based on viewing volume aspect ratio. The control sequence determination device automatically selects optimal directions for first and second pulse arrangements, reducing sensitivity to B0 inhomogeneities and chemical shift effects while maintaining reasonable sequence design complexity.
3Volume of moving object
If the viewing volume dimensions are increased to improve diagnostic coverage, then more tissue is visualized, but the risk of aliasing artifacts increases
Solution Approach 1:
The patent utilizes the aspect ratio of viewing volume dimensions as a key parameter to determine optimal pulse arrangement directions. By analyzing the relative dimensions in different spatial directions and selecting appropriate first and second selection directions, the system maintains diagnostic coverage while minimizing aliasing artifacts through parameter-optimized pulse sequences.
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 reduces the risk of aliasing artifacts by optimizing the selection directions according to the viewing volume's dimensions, improving image quality by reducing sensitivity to B0 inhomogeneities and chemical shift effects.
Implementation Method 1
radio-frequency excitation signals (RF signals) are then emitted (radiated) by suitable antennas, which cause nuclear spins of specific atoms to be excited to resonance by the associated radio-frequency field (B1 field)
Implementation Method 2
A magnetic field gradient is additionally applied by a gradient system
Implementation Method 3
A magnetic field gradient is additionally applied by a gradient system
Implementation Method 4
radio-frequency excitation signals (RF signals) are then emitted (radiated) by suitable antennas, which cause nuclear spins of specific atoms to be excited to resonance by the associated radio-frequency field (B1 field). This excitation can be described as the nuclear spins being flipped (deflected) by a defined flip angle relative to the magnetic field lines of the basic magnetic field
Implementation Method 5
Upon relaxation of the nuclear spins, radio-frequency signals, known as magnetic resonance signals, are radiated that are then received (detected) by suitable reception antennas
Data Source
AI summary
In a method and device for the determination of a magnetic resonance control sequence that includes at least one first pulse arrangement that acts in a spatially selective manner in a first selection direction and a subsequent second pulse arrangement that acts in a spatially selective manner in a second selection direction, viewing volume dimension parameter values are registered that define the spatial extent of a viewing volume to be excited. The first selection direction and the second selection direction are established automatically depending on a length ratio of the spatial extent of the viewing volume to be excited in the different selection directions.