Magnetic Resonance Fingerprinting Fat Peak Weight Calibration
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Solution Overview
Problem
In quantitative magnetic resonance imaging, the modulation of fat peaks due to T1 and T2 relaxation and J coupling effects in fatty acids leads to errors in water-fat separation, particularly when using conventional Dixon reconstructions with assumed fat peak weights, which are not accurate for magnetic resonance fingerprinting pulse sequences.
Innovation Solution
The use of fat peak weights measured or pre-calibrated specifically for the magnetic resonance fingerprinting pulse sequence, combined with k-space data acquisition and reconstruction techniques such as MRF, model-based reconstructions, or neural networks, to accurately separate water and fat signals, accounting for variations in fat spectrum due to dephasing and relaxation effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional Dixon reconstruction with assumed fat peak weights is used, then the reconstruction process is simple and fast, but the accuracy of water-fat separation deteriorates due to modulation effects from T1 and T2 relaxation and J coupling
Solution Approach 1:
The patent applies preliminary action by pre-calculating fat peak weights specifically for the MRF pulse sequence before the actual water-fat separation process. This pre-computed fat spectrum information is then used during reconstruction to accurately account for modulation effects from T1 and T2 relaxation and J coupling, thereby improving separation accuracy without adding computational burden during the main reconstruction process
Solution Approach 2:
The patent changes the parameter of fat peak weights from conventional assumed values to sequence-specific pre-computed values. By adjusting this parameter to match the actual MRF pulse sequence characteristics, the method resolves the inaccuracy caused by using generic fat spectrum assumptions, thereby improving water-fat separation precision while maintaining reconstruction efficiency
2Measurement precision
If fat peak weights are pre-calibrated for the specific pulse sequence, then water-fat separation accuracy is improved, but the complexity of the reconstruction process increases
Solution Approach 1:
The patent resolves the complexity issue by performing the computationally intensive fat peak weight calculation as a preliminary step before the actual MRF reconstruction. This pre-computation approach separates the complex calibration process from the routine reconstruction process, allowing accurate sequence-specific fat weights to be used without burdening the real-time reconstruction workflow
Solution Approach 2:
The patent uses copying by creating a reference fat spectrum model that is specific to the MRF pulse sequence. This pre-computed fat spectrum copy is then reused during water-fat separation, avoiding the need to recalculate complex modulation effects during each reconstruction, thereby maintaining accuracy while reducing computational complexity during actual operation
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 improves the accuracy of quantitative magnetic resonance images by tailoring fat peak weights to the specific pulse sequence, reducing errors associated with conventional assumptions and enhancing the precision of water-fat separation in the presence of fat-containing tissues.
Implementation Method 1
a magnetic resonance fingerprinting pulse sequence that is configured for encoding chemical shifts. A magnetic resonance fingerprinting pulse sequence configured for encoding chemical shifts could comprise the acquisition of the k-space data at various echo times
Implementation Method 2
the modulation of the various fat peaks in the magnetic resonance spectrum due to T1 and T2 relaxation and J coupling effects
Implementation Method 3
the modulation of the various fat peaks in the magnetic resonance spectrum due to T1 and T2 relaxation and J coupling effects
Implementation Method 4
the magnetization flip angle train used during the acquisition of k-space data can cause the J-couplings between the various protons within the fatty acids to interact
Data Source
AI summary
A medical system including a memory storing machine executable instructions is disclosed. The medical system also includes a computational system. The execution of the machine executable instructions causes the computational system to receive k-space data descriptive of a region of interest of a subject. The k-space data are acquired using a magnetic resonance fingerprinting pulse sequence configured for encoding chemical shifts. The execution of the machine executable instructions also causes the computational system to receive fat peak weights descriptive of a magnetic resonance fat spectrum. The fat peak weights are matched to a pulse train of the magnetic resonance fingerprinting pulse sequence. The execution of the machine executable instructions also causes the computational system to reconstruct a quantitative magnetic resonance image from the k-space data and the fat peak weights.