MRI Gradient Pulse Slew Rate Optimization
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Solution Overview
Problem
Magnetic resonance imaging systems face challenges in reducing noise exposure and energy consumption while maintaining image quality, as high gradient pulse steepness leads to noise, energy demands, and image distortions, and existing solutions compromise between noise reduction, measurement time, and image quality.
Innovation Solution
A method for determining a control sequence that optimizes gradient pulse steepness and RF pulse parameters, including a spatial slice selection gradient pulse and refocusing pulses, to adapt to the hardware and examination subject, ensuring the control sequence is executable and adaptable without significant compromises in noise generation or image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high gradient pulse steepness (high slew rate) is used, then spatial encoding precision and measurement time are improved, but noise exposure and energy consumption increase
Solution Approach 1:
The patent applies different maximum slew rate limits to different gradient coils (e.g., slice selection gradient vs. phase encoding gradient) based on their specific roles and noise characteristics. This allows optimizing spatial encoding precision in less noise-sensitive directions while reducing noise in more sensitive directions, rather than applying a uniform global limit.
Solution Approach 2:
The system dynamically adjusts the maximum slew rate based on the specific pulse sequence being executed and the current measurement context. The control sequence determination device calculates optimal slew rate parameters adaptively, allowing high slew rates when needed for precision while reducing them when noise becomes problematic, rather than using fixed limits.
2Measurement precision
If high gradient pulse steepness (high slew rate) is used, then spatial encoding precision is improved, but energy consumption increases
Solution Approach 1:
The patent optimizes energy consumption by applying slew rate limits selectively to different gradient coils based on their energy consumption characteristics and operational requirements. Less energy-intensive coils can operate at higher slew rates when needed, while more energy-intensive coils operate at reduced slew rates, achieving spatial encoding precision without excessive overall energy consumption.
3Object-affected harmful factors
If low maximum slew rate is set for noise reduction, then noise exposure is reduced, but measurement time increases
Solution Approach 1:
The patent reduces measurement time by allowing higher slew rates in gradient directions where noise is less problematic (e.g., phase encoding direction) while maintaining lower slew rates in directions where noise sensitivity is higher. This selective approach preserves image quality and reduces artifacts while minimizing the overall measurement time penalty.
Solution Approach 2:
The system dynamically determines the maximum slew rate based on the specific pulse sequence parameters and measurement requirements. The control sequence determination device calculates optimal slew rate values that balance noise reduction with measurement time efficiency, adapting to different imaging protocols rather than using fixed conservative limits.
4Object-affected harmful factors
If low maximum slew rate is set for noise reduction, then noise exposure is reduced, but image quality deteriorates
Solution Approach 1:
The patent maintains image quality by applying higher slew rates in gradient directions and pulse sequence segments where the imaging is less sensitive to noise-induced artifacts, while using lower slew rates where image quality is more vulnerable. This directional and contextual optimization preserves contrast, resolution, and artifact levels while still achieving noise reduction benefits.
Solution Approach 2:
The control sequence determination device dynamically calculates optimal maximum slew rate values that maintain image quality standards while reducing noise. The system adapts slew rate parameters based on the specific imaging protocol, tissue type, and quality requirements, ensuring that noise reduction does not come at the cost of diagnostic image quality.
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
The method effectively reduces noise exposure and energy consumption while maintaining image quality by optimizing gradient pulse steepness and RF pulse parameters, ensuring the control sequence is executable and adaptable to the magnetic resonance imaging system and examination subject.
Implementation Method 1
A magnetic field gradient is additionally applied with the aid of a gradient system. Radio-frequency excitation signals (RF signals) are then emitted by suitable antenna devices via a radio-frequency transmission system, which cause nuclear spins of specific atoms to be excited to resonance
Implementation Method 2
Radio-frequency excitation signals (RF signals) are then emitted by suitable antenna devices via a radio-frequency transmission system, which cause nuclear spins of specific atoms to be excited to resonance by being deflected, by an amount known as a defined 'flip angle', relative to the magnetic field lines of the basic magnetic field
Implementation Method 3
the body to be examined is typically exposed in a scanner 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
Starting with a magnetic resonance imaging system control sequence that has a radio-frequency (RF) pulse train to control the RF transmission system and a gradient pulse train, chronologically matching the RF pulse train, to control the gradient system, the gradient pulse train including a predetermined selection gradient pulse chronologically matched to a refocusing pulse of the RF pulse train, the execution capability of the control sequence is initially established using an execution capability criterion, in particular under consideration of a refocusing flip angle of the refocusing pulse. Modification of the refocusing pulse and/or of the selection gradient pulse takes place depending on the establishment of the execution capability of the control sequence.