MR Scanner RF Phase Cycling and Gradient Spoiling for Coherence Path Suppression
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Solution Overview
Problem
Magnetic resonance sequences using modules, such as saturation modules, face challenges in determining coherence paths, leading to undesirable signal generation and interference in scan data due to the inability to assess sequences with changed parameters in advance.
Innovation Solution
Implementing a method where an MR data acquisition scanner operates with multiple excitation cycles, using different phases for radio-frequency pulses and applying dephasing gradients to eliminate transverse magnetization, allowing for simultaneous RF and gradient spoiling, which can be applied in any sequence, including those with modules, to suppress unwanted coherence paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If modules are used in the recording of a data record to enable flexible sequence construction, then adaptability is improved, but determination of coherence paths becomes impossible or restricted, leading to undesirable signal generation
Solution Approach 1:
The patent applies parameter changes by systematically varying the phase of radio-frequency pulses across different excitation cycles. This phase modulation transforms the coherent unwanted signals into incoherent ones, effectively suppressing interference while preserving the modular sequence structure and its adaptability.
Solution Approach 2:
The patent converts the harmful effect of coherent unwanted signals generated by modules into a beneficial outcome. By intentionally introducing phase variations, the unwanted coherent signals are transformed into random-phase signals that cancel each other out, turning the problem of signal interference into a solution for noise suppression.
2Manufacturing precision
If saturation modules are used to eliminate magnetization at defined time points, then image contrast is improved, but transverse magnetization may not be completely eliminated, leading to residual unwanted signals
Solution Approach 1:
The patent merges two spoiling techniques: RF spoiling (phase cycling of radio-frequency pulses) and gradient spoiling (application of dephasing gradients). This combination ensures that both longitudinal and transverse magnetization are effectively eliminated, preventing residual unwanted signals while maintaining the desired image contrast from saturation modules.
Solution Approach 2:
The patent employs a composite approach by integrating multiple spoiling mechanisms into a unified sequence structure. The combination of phase-modulated RF pulses and dephasing gradients creates a synergistic effect that more effectively eliminates unwanted magnetization than either method alone, while preserving the modular architecture.
3Reliability
If multiple excitation cycles are executed with phase variations in radio-frequency pulses, then unwanted coherence paths are suppressed, but sequence complexity increases
Solution Approach 1:
The patent implements periodic action through systematic phase cycling across multiple excitation cycles. The phase of radio-frequency pulses follows a predetermined periodic pattern, which ensures that unwanted coherent signals are suppressed while the overall sequence structure remains regular and manageable, avoiding excessive complexity.
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 fault-prone scan data recording by effectively eliminating undesirable signals and enhancing the reliability of MR data acquisition, enabling better image formation and data processing.
Implementation Method 1
Different phases are used in a first radio-frequency pulse, as the excitation pulse, in two successive excitation cycles.
Implementation Method 2
The computer also operates the MR scanner so as to apply (activate) at least one dephasing gradient in an excitation cycle.
Implementation Method 3
As these excited nuclear spins and relax and return to the steady-state condition, they emit further RF signals, called MR signals.
Data Source
AI summary
In a method and apparatus for generating a magnetic resonance data record, at least two excitation cycles are executed, wherein, in each excitation cycle, at least one magnetic resonance signal is recorded, using different phases with a first radio-frequency pulse in two consecutive excitation cycles, with at least one dephasing gradient being applied in an excitation cycle.