Amplitude Modulated Gradient Switching for Fat Saturation
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Solution Overview
Problem
Current magnetic resonance imaging techniques face challenges in achieving effective fat saturation while maintaining image quality, as reducing gradient amplitude to suppress fat signals requires longer pulse durations, which can reduce signal strength and quality.
Innovation Solution
The method involves activating a first gradient switching operation during an excitation pulse and a second gradient switching operation with opposite polarity during a refocusing pulse, with amplitude modulation during either pulse to optimize fat saturation without increasing pulse duration, using techniques like variable-rate selective excitation and amplitude modulation to ensure effective suppression of fat signals while preserving signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If gradient amplitude is reduced to suppress fat signals, then fat saturation is improved, but pulse duration increases which reduces signal strength and image quality
Solution Approach 1:
The gradient amplitude is dynamically modulated during the pulse sequence rather than being static. The amplitude is reduced during specific time intervals when fat signals are being suppressed, while maintaining higher amplitudes at other times to preserve signal strength and keep pulse duration short. This dynamic adjustment resolves the contradiction between fat suppression and maintaining image quality.
Solution Approach 2:
The gradient switching operations are applied periodically with alternating polarities during the excitation and refocusing pulses. This periodic gradient reversal creates conditions that selectively suppress fat signals while allowing water signals to maintain their strength, thereby achieving fat saturation without requiring increased pulse duration.
2Object-affected harmful factors
If gradient amplitude is reduced to suppress fat signals, then fat saturation is improved, but image quality deteriorates
Solution Approach 1:
The gradient amplitude is dynamically modulated during the pulse sequence rather than being static. The amplitude is reduced during specific time intervals when fat signals are being suppressed, while maintaining higher amplitudes at other times to preserve signal strength and keep pulse duration short. This dynamic adjustment resolves the contradiction between fat suppression and maintaining image quality.
Solution Approach 2:
Different gradient amplitudes are applied at different time points within the pulse sequence. Specifically, lower amplitudes are used during periods critical for fat suppression, while higher amplitudes are maintained during periods critical for maintaining image quality and signal strength. This localized differentiation of gradient strength achieves both fat saturation and image quality preservation.
3Manufacturing precision
If gradient switching operations are applied to achieve fat saturation, then contrast between fatty and water tissues is improved, but pulse duration increases
Solution Approach 1:
The gradient switching operations are applied periodically with alternating polarities during the excitation and refocusing pulses. This periodic gradient reversal creates conditions that selectively suppress fat signals while allowing water signals to maintain their strength, thereby achieving fat saturation without requiring increased pulse duration.
Solution Approach 2:
The gradient amplitude is dynamically modulated during the pulse sequence rather than being static. The amplitude is reduced during specific time intervals when fat signals are being suppressed, while maintaining higher amplitudes at other times to preserve signal strength and keep pulse duration short. This dynamic adjustment resolves the contradiction between fat suppression and maintaining 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
This approach enhances fat saturation while maintaining image quality by minimizing the overlap of excitation and refocusing slices of fat tissue, thus improving contrast between fatty and water tissues without compromising signal strength or duration of pulses.
Implementation Method 1
the nuclear spins of specific atoms excited in a resonant manner by these radio-frequency pulses being tilted by a defined flip angle with respect to the magnetic field lines of the basic magnetic field
Implementation Method 2
The refocusing pulse can be designed for generating a spin echo of the spins excited by the excitation pulse
Implementation Method 3
gradient switching operations are activated with the use of a gradient coil arrangement
Data Source
AI summary
In a method and magnetic resonance (MR) apparatus for acquiring MR signals of an examination object, an excitation pulse is radiated while a first gradient switching operation is activated, a refocusing pulse is radiated, a second gradient switching operation is activated with the second gradient switching operation having an opposite polarity to the first gradient switching operation. At least one of the first gradient switching operation and the second gradient switching operation has an amplitude modulation during radiation of the excitation pulse or the refocusing pulse. MR signals are acquired from nuclear spins in a body of the examination object that were excited by the excitation pulse and refocused by the refocusing pulse.