RF Preparation Pulse for Homogeneous Fat Saturation in MRI
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Solution Overview
Problem
Existing methods for fat saturation in magnetic resonance imaging (MRI) result in inhomogeneous fat signal intensity distribution when acquiring MR data in slices, particularly due to varying measurement parameters affecting the first slice differently than subsequent slices.
Innovation Solution
A method that determines the flip angle for an RF preparation pulse based on the requirement for fat signal saturation, ensuring uniform fat saturation across all slices by measuring the fat signal for different flip angles and establishing a relationship between the flip angle and resulting fat signal, allowing for optimal selection of the flip angle to achieve maximum fat saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If slice-based MR data acquisition is performed with conventional SPAIR pulse, then measurement time is reduced, but fat saturation becomes inhomogeneous across slices
Solution Approach 1:
An RF preparation pulse is applied before the SPAIR pulse to pre-condition the magnetization state. This preliminary action ensures that when slice-based acquisition is performed, the fat saturation remains homogeneous across all slices by preparing the spins in advance, thus maintaining both fast acquisition and uniform saturation.
Solution Approach 2:
The invention introduces a specific flip angle parameter for the RF preparation pulse that is determined based on the desired fat signal requirement. By optimizing this parameter, the method achieves homogeneous fat saturation across slices while maintaining efficient measurement timing.
2Manufacturing precision
If flip angle is increased to improve fat saturation, then fat signal is reduced, but measurement time increases due to need for optimization
Solution Approach 1:
The system performs an automatic determination of the optimal flip angle based on the desired fat signal requirement. This self-service approach eliminates the need for manual optimization and extensive measurement time, as the flip angle is calculated directly from the fat signal requirement and applied in the RF preparation pulse.
3Device complexity
If conventional SPAIR pulse is used without RF preparation pulse, then sequence is simpler, but fat saturation is insufficient for first slice
Solution Approach 1:
The RF preparation pulse is applied before the SPAIR pulse to pre-condition the magnetization state. This preliminary action ensures that when slice-based acquisition is performed, the fat saturation remains homogeneous across all slices by preparing the spins in advance, thus maintaining both fast acquisition and uniform saturation.
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 ensures homogeneous fat saturation across all slices, avoiding inhomogeneous intensity distribution in reconstructed MR images without increasing measurement time, particularly effective in single-shot acquisitions using the SPAIR pulse.
Implementation Method 1
an RF preparation pulse which has the flip angle is emitted
Implementation Method 2
The SPAIR pulse ('Spectrally Adiabatic Inversion Recovery') is a frequency-selective adiabatic inversion pulse that is emitted in order to invert only spins of the fat tissue
Implementation Method 3
The SPAIR pulse ('Spectrally Adiabatic Inversion Recovery') is a frequency-selective adiabatic inversion pulse that is emitted in order to invert only spins of the fat tissue
Implementation Method 4
The SPAIR pulse ('Spectrally Adiabatic Inversion Recovery') is a frequency-selective adiabatic inversion pulse
Implementation Method 5
when acquiring MR data in a predetermined volume segment of an examination object with the operation of a magnetic resonance system
Data Source
AI summary
In a method and a magnetic resonance (MR) system for fat saturation when acquiring MR data in a predetermined volume segment of an examination object (O), a flip angle is determined as a function of a predetermined requirement for a fat signal that is acquired by the magnetic resonance system in the volume segment, and an RF preparation pulse is emitted that has the determined flip angle. This is followed by emission of a SPAIR pulse, followed by acquisition of the MR data.