Magnetic Resonance Pulse Sequence Optimization for Gradient Noise Reduction
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Solution Overview
Problem
Magnetic resonance systems face challenges in minimizing noise and power consumption due to high gradient strengths and slew rates, leading to heating and helium boil-off, while maintaining image quality and short examination times.
Innovation Solution
An optimization method for pulse sequences that automatically identifies fixed and modifiable time intervals in gradient pulses, allowing for smoothing of gradient pulse shapes to reduce noise and slew rates, implemented using a pulse sequence optimization device that can be integrated into existing magnetic resonance systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high gradient strengths and slew rates are used to achieve short examination times, then productivity is improved, but noise exposure and power consumption increase
Solution Approach 1:
The patent applies dynamics by making the gradient pulse parameters adjustable and optimizable. The system allows dynamic modification of gradient pulse shapes, amplitudes, and timing to balance examination speed with noise reduction, rather than using fixed high-gradient parameters throughout the sequence
Solution Approach 2:
The patent implements parameter changes by optimizing gradient pulse parameters (amplitude, duration, shape) and RF pulse parameters (flip angle, timing) to reduce noise while maintaining examination efficiency. The system modifies these parameters based on noise criteria and sequence requirements
2Productivity
If high gradient strengths and slew rates are used to achieve short examination times, then productivity is improved, but power consumption increases
Solution Approach 1:
The system dynamically adjusts gradient pulse parameters to minimize power consumption while maintaining acceptable examination times. By optimizing the gradient waveform shapes and timing, the system reduces peak power demands and overall energy usage
Solution Approach 2:
The patent changes gradient pulse parameters (amplitude, duration, rise time) and RF pulse parameters to reduce power consumption. The optimization process specifically targets parameters that have the greatest impact on power usage while maintaining sequence effectiveness
3Productivity
If high gradient strengths and slew rates are used to achieve short examination times, then productivity is improved, but heating and helium boil-off increase
Solution Approach 1:
The system dynamically optimizes gradient pulse parameters to reduce heating effects. By adjusting the gradient waveform shapes and duty cycles, the system minimizes the thermal load on the gradient coils and superconducting magnet, reducing helium boil-off
Solution Approach 2:
The patent modifies gradient and RF pulse parameters to reduce temperature increase and helium consumption. The optimization specifically addresses parameters that generate heat, such as gradient amplitude and pulse duration, while maintaining sequence performance
4Object-generated harmful factors
If gradient pulse shapes are smoothed to reduce noise and slew rates, then noise exposure and power consumption are reduced, but examination duration may increase
Solution Approach 1:
The system dynamically balances gradient pulse smoothing with timing constraints. The optimization process adjusts the degree of smoothing applied to different gradient pulses based on their position in the sequence and their impact on examination duration, achieving a optimal compromise between noise reduction and time efficiency
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 noise exposure, lowers power consumption, and minimizes helium boil-off without extending examination duration or compromising image quality, enabling more cost-effective gradient coil design and improved system performance.
Implementation Method 1
A magnetic field gradient is additionally applied by a gradient system. Via suitable antenna devices, radio-frequency excitation signals (RF signals) are then emitted from a radio-frequency transmission system
Implementation Method 2
Eddy currents with other components of the magnetic resonance scanner (data acquisition unit)—in particular the radio-frequency shield—are one reason for this noise development
Implementation Method 3
The rapidly changing gradient fields lead to distortions and oscillations in the gradient coils and to the transfer of these energies to the housing
Implementation Method 4
In a magnetic resonance system—also called a magnetic resonance tomography system—the body to be examined is typically exposed to a relatively high basic magnetic field (for example of 1, 5, 3 or 7 Tesla) with the use of a basic field magnet system
Data Source
AI summary
In a method and a pulse sequence optimization device to determine a pulse sequence for a magnetic resonance system, a pulse sequence is selected for optimization that includes a number of radio-frequency pulses and a number of gradient pulses chronologically coordinated therewith. An automatic analysis of the pulse sequence takes place to identify fixed point/time periods in the pulse sequence that are to be left unmodified, and modifiable time intervals in the pulse sequence that may be optimized. An automatic optimization of gradient pulses in the modifiable time intervals takes place according to a predetermined optimization criterion, while keeping the length of modifiable time intervals constant.