Spectroscopic Magnetic Resonance Fingerprinting for Phosphorus-31 Metabolite Quantification
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Solution Overview
Problem
Conventional 31P magnetization transfer (MT)-MRS methods face limitations due to long data acquisition times and low signal-to-noise ratios (SNR), which restrict their utility in evaluating ATP synthesis and other metabolic processes, especially in pathological conditions where T1 values of phosphocreatine (PCr) may not remain constant.
Innovation Solution
The implementation of spectroscopic magnetic resonance fingerprinting (MRF) using a series of varied sequence blocks to acquire signal evolutions from a subject, comparing these to an MRF dictionary to characterize metabolites and determine parameters such as T1 relaxation times and chemical exchange rates, allowing for faster and more flexible pulse sequence design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional 31P MT-MRS methods are used to measure metabolite concentrations, then chemical specificity is achieved, but data acquisition time becomes excessively long
Solution Approach 1:
The patent segments the measurement process into multiple spectral acquisitions with different saturation transfer conditions. Instead of acquiring a single long spectrum, multiple shorter spectra are acquired with varying saturation pulses applied to different metabolite resonances, enabling parallel measurement of multiple metabolite parameters through pattern recognition algorithms
Solution Approach 2:
The patent employs periodic saturation pulses applied at different frequencies and durations in a systematic sequence. These periodic actions create distinct signal modulation patterns for different metabolites, which are then decoded through spectral analysis to simultaneously determine multiple metabolite concentrations and exchange rates
2Productivity
If the number of acquired spectra is reduced to shorten acquisition time, then productivity improves, but signal-to-noise ratio deteriorates
Solution Approach 1:
The patent performs preliminary signal averaging and noise filtering on individual spectral components before combining them into the final metabolite quantification. By pre-processing the signal to enhance the signal-to-noise ratio of individual spectral peaks, the method enables accurate metabolite measurement even with reduced numbers of acquisitions
Solution Approach 2:
The patent uses iterative optimization where initial metabolite estimates are refined through feedback from the spectral patterns. The system adjusts saturation pulse parameters and acquisition sequences based on preliminary results, optimizing the signal-to-noise ratio while maintaining shortened acquisition times
3Device complexity
If T1 value of PCr is fixed to reduce unknown parameters, then device complexity decreases, but measurement precision worsens in pathological conditions
Solution Approach 1:
The patent transitions from static T1 value assumptions to dynamic T1 measurement. By incorporating T1 estimation into the spectral analysis framework using the acquired saturation transfer patterns, the system adaptively determines T1 values specific to each subject and pathological condition, eliminating the need for fixed T1 assumptions while maintaining parameter tractability
Solution Approach 2:
The patent changes the measurement approach from directly measuring T1 to measuring T1-dependent spectral patterns. By observing how metabolite signal intensities change with varying saturation transfer conditions, the system indirectly determines T1 values as part of the metabolite quantification process, allowing T1 to vary with pathological conditions without increasing measurement complexity
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
MRF enables faster acquisition times while maintaining accurate quantification of metabolic parameters, improving the diagnosis of metabolic disorders by providing unique signal evolution patterns associated with tissue properties like T1 and T2 relaxation times, perfusion, and diffusion, thus overcoming the limitations of conventional MT-MRS.
Implementation Method 1
a magnet system configured to generate a polarizing magnetic field about at least a portion of a subject
Implementation Method 2
a magnetic gradient system including a plurality of magnetic gradient coils configured to apply at least one magnetic gradient field to the polarizing magnetic field
Implementation Method 3
a radio frequency (RF) system configured to apply an RF field to the subject and to receive magnetic resonance signals from the subject
Data Source
AI summary
The present disclosure relates to a method for performing phosphorous-31 spectroscopic magnetic resonance fingerprinting (MRF). The method comprises performing a pulse sequence using a series of varied sequence blocks to a volume in a subject where the volume contains phosphate metabolites. A series of signal evolutions are acquired from the volume in the subject to form MRF data. The MRF data is then compared to simulated MRF signal to determine parameters associated with phosphate metabolites and the chemical exchange rates between these metabolites. These parameters and exchange rates can be used in diagnosing a metabolic disorder in a subject.