B1 Field Regulation in MRT Sequences
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Solution Overview
Problem
Magnetic resonance tomography (MRT) systems face instability issues due to timing drift and heating, which affect the B1 magnetic field, leading to changes in signal quality and image fidelity, particularly in high-loading applications like fMRI and DTI, where existing temperature stabilization and amplifier regulation methods are insufficient.
Innovation Solution
Implementing a B1 magnetic field regulation method that uses reference and calibration pulses to adjust the voltage and current of high-frequency pulses, allowing for precise calibration and adaptation of the B1 field strength throughout the MRT imaging sequence, thereby maintaining consistent signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-loading applications like fMRI and DTI are performed, then productivity and imaging capability are improved, but timing drift and heating occur causing B1 field instability
Solution Approach 1:
The patent implements a feedback mechanism where the B1 field is continuously monitored during the MRT sequence using a B1 measurement, and the measured value is fed back to adjust the voltage of subsequent RF pulses. This closed-loop control compensates for timing drift and heating effects, maintaining B1 field stability even during high-loading applications like fMRI and DTI.
Solution Approach 2:
The patent dynamically changes the voltage parameter of RF pulses based on measured B1 field values. By adjusting the voltage in real-time according to the measured B1 field strength, the system compensates for drift and heating effects, resolving the contradiction between maintaining high imaging capability and ensuring B1 field stability.
2Reliability
If temperature stabilization and amplifier regulation are used, then B1 field stability is improved, but device complexity increases
Solution Approach 1:
The patent implements a self-service mechanism where the MRT system automatically performs B1 field measurement and self-adjusts the RF pulse voltage without requiring external temperature stabilization systems or complex amplifier regulation. The system uses its own RF pulses to measure and correct B1 field variations, reducing device complexity while maintaining stability.
Solution Approach 2:
The feedback mechanism measures the actual B1 field strength and automatically adjusts subsequent RF pulses to compensate for variations. This simple feedback loop replaces complex temperature stabilization and amplifier regulation systems, achieving B1 field stability with minimal additional complexity.
3Measurement precision
If real-time B1 field measurement and adjustment are implemented, then signal quality is improved, but measurement precision requirements increase
Solution Approach 1:
The patent uses the main RF coil to serve multiple functions: it both applies the B1 field for imaging and measures the B1 field strength through the emitted signal. This multi-functionality eliminates the need for separate, highly precise measurement devices, reducing measurement precision requirements while maintaining signal quality.
Solution Approach 2:
The system uses its own RF transmission and the resulting emitted signal to measure the B1 field. This self-measurement approach leverages the existing imaging infrastructure, avoiding the need for additional precision measurement equipment and simplifying the measurement 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 approach stabilizes the B1 field, minimizing signal fluctuations and maintaining image quality by dynamically adjusting the B1 field strength based on real-time measurements, effectively addressing the instability issues caused by heating and timing drift.
Implementation Method 1
The nuclear resonance of atomic nuclei of the body 105 is excited by magnetic high-frequency excitation pulses B1(x, y, z, t) radiated into the nuclei via a high-frequency antenna
Implementation Method 2
The gradient coils 112x, 112y, 112z with which magnetic gradient fields BG(x, y, z, t) are radiated during a measurement for selective slice excitation and for local encoding of the measurement signal
Implementation Method 3
The signals emitted by the excited nuclear spins of the atomic nuclei in the object under examination are received by the body coil 108 and/or at least one local coil arrangement 106
Data Source
AI summary
A B1 magnetic field may be regulated during a magnetic resonance tomography (MRT) imaging sequence.