MRI Preparation Pulse Frequency Adjustment for Fat Saturation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic resonance imaging techniques face challenges in achieving homogeneous fat saturation and minimizing unwanted water saturation due to magnetic field inhomogeneities, especially in larger target volumes, where spatial variations in the magnetic field lead to incomplete saturation and water saturation issues.
Innovation Solution
The method involves dynamically adjusting the pulse frequency and bandwidth of preparation pulses as a function of resonance information describing the resonance frequencies of both the saturation molecule and the target molecule within contiguous partial volumes, allowing for optimal pulse parameter selection for each measured slice or slice group, and adjusting the acquisition sequence to minimize interference saturations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency-selective preparation pulses are used for fat saturation across the entire target volume, then fat saturation is achieved, but incomplete saturation and unwanted water saturation occur in regions with magnetic field inhomogeneities
Solution Approach 1:
The patent applies local quality by adjusting the pulse frequency of preparation pulses based on the spatial position within the target volume. Different regions with different magnetic field inhomogeneities receive customized pulse frequencies optimized for their local conditions, rather than using a single uniform frequency for the entire volume. This resolves the contradiction by making the saturation effective locally in each region without causing unwanted water saturation in other regions.
Solution Approach 2:
The patent implements dynamics by dynamically adjusting the pulse frequency parameter of preparation pulses as a function of the measured slice position or anatomical region. The frequency is not fixed but varies adaptively across different spatial locations to compensate for magnetic field inhomogeneities, thereby maintaining reliable fat saturation while avoiding water saturation in inhomogeneous regions.
2Volume of moving object
If the target volume is increased to cover larger anatomical regions, then more comprehensive imaging is achieved, but spatial variations in magnetic field increase causing severe saturation problems
Solution Approach 1:
The patent resolves this contradiction by applying local quality through position-dependent pulse frequency adjustment. Each local region within the enlarged target volume receives a customized frequency tailored to its specific magnetic field conditions, allowing comprehensive coverage while maintaining uniform saturation reliability across all regions despite spatial variations in the magnetic field.
Solution Approach 2:
The patent applies segmentation by dividing the large target volume into multiple measured slices or anatomical regions, each processed with locally optimized pulse parameters. This segmentation allows the system to handle large volumes by treating each subset independently with region-specific frequency adjustment, thereby maintaining saturation uniformity across the entire extended volume.
3Device complexity
If fixed pulse frequency is used for preparation pulses, then simple implementation is maintained, but homogeneous fat saturation cannot be achieved across different anatomical regions
Solution Approach 1:
The patent resolves this contradiction by transitioning from a static fixed frequency approach to a dynamic position-dependent frequency adjustment. The pulse frequency automatically adapts to the local magnetic field conditions based on the measured slice position or anatomical region, achieving homogeneous fat saturation across different regions while adding only minimal computational complexity for determining and applying the position-dependent frequencies.
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 results in more homogeneous fat saturation and improved image quality by accurately considering the relative relationships between resonance frequency spectra, reducing unwanted water saturation and enhancing the overall quality of magnetic resonance data.
Implementation Method 1
Such fat saturation techniques mostly exploit the fact that the resonance frequencies of fat and water are slightly different, this being known as chemical shift
Implementation Method 2
a preparation pulse, which can also be called a saturation pulse, is emitted, and excites only the spin of the type of molecule whose signal is to be suppressed, such that the magnetization thereof is saturated
Data Source
AI summary
In a method and apparatus for acquiring magnetic resonance data from a slice package composed of multiple measured slices as a target volume by executing a measuring sequence, prior to each scan of one of the measured slices, the measuring sequence includes a preparation pulse associated with the measured slice for signal suppression of a type of saturation molecule. This said preparation pulse acts on the entire target volume, and a pulse parameter of the preparation pulse is chosen for a measured slice group, composed of at least one measured slice, as a function of resonance information on the contiguous partial volume covered by the measured slice group. The pulse frequency and/or the pulse bandwidth are chosen as pulse parameters as a function of resonance information describing at least the resonance frequencies of the type of saturation molecule and a type of target molecule, the magnetic resonance data of which is to be acquired, in the contiguous partial volume of the target volume that covers the measured slice group.