Magnetic Resonance Fingerprinting Acquisition Optimization
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Solution Overview
Problem
Magnetic resonance fingerprinting (MRF) techniques face challenges in accurately estimating quantitative parameters in the presence of inhomogeneous static magnetic fields and RF transmit fields, which limits their effectiveness and increases the cost and complexity of MRI systems.
Innovation Solution
The method optimizes acquisition parameters to generate signal evolutions that maximize discrimination between magnetic resonance patterns in a reduced number of repetition time periods, using a dictionary database with flip angle homogeneity values to estimate quantitative parameters and RF coil transmission profiles, allowing for accurate MRF even in inhomogeneous fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MRF techniques are used with standard acquisition parameters, then quantitative parameter estimation can be performed, but accuracy deteriorates in the presence of inhomogeneous magnetic fields
Solution Approach 1:
The patent optimizes acquisition parameters including flip angle, repetition time, echo time, and sampling patterns to maximize discrimination between magnetic resonance signal patterns. This parameter optimization enables accurate quantitative parameter estimation even in the presence of inhomogeneous magnetic fields by tailoring the acquisition sequence to the specific field conditions.
Solution Approach 2:
The patent uses a dictionary of pre-computed signal templates that model expected magnetic resonance signal evolutions under various conditions. By comparing acquired signals against this dictionary of reference patterns, the system can accurately estimate quantitative parameters despite field inhomogeneities, effectively using the dictionary as a reference copy for comparison.
2Measurement precision
If more repetition time periods are used to improve signal discrimination, then parameter estimation accuracy improves, but scan time increases
Solution Approach 1:
The patent optimizes the number and values of repetition time periods used in the acquisition sequence. By carefully selecting the optimal number of TR periods and their specific duration values, the method achieves sufficient signal pattern discrimination for accurate parameter estimation while minimizing the total scan time required.
Solution Approach 2:
The patent determines the minimum necessary number of repetition time periods required to achieve adequate signal discrimination. Rather than using excessive numbers of TR periods, the optimized sequence uses just enough repetitions to achieve the required measurement precision, thereby reducing unnecessary scan time while maintaining adequate accuracy.
3Measurement precision
If highly homogeneous magnetic field hardware is used to ensure accurate MRF, then measurement precision improves, but device cost and complexity increase
Solution Approach 1:
The patent converts the previously harmful effect of magnetic field inhomogeneity into a manageable parameter by optimizing the acquisition sequence specifically for inhomogeneous conditions. Rather than requiring expensive homogeneous field hardware, the method embraces field variations and uses optimized parameters to achieve accurate measurements, effectively turning the hardware limitation into an acceptable operating condition.
Solution Approach 2:
The patent changes the acquisition parameters to compensate for hardware limitations. By optimizing flip angles, repetition times, and sampling patterns, the method achieves accurate quantitative parameter estimation without requiring highly homogeneous magnetic field hardware, thereby reducing device cost and complexity while maintaining measurement precision.
4Productivity
If acquisition parameters are optimized to reduce number of TR periods, then scan time decreases, but signal discrimination capability may worsen
Solution Approach 1:
The patent performs comprehensive optimization of all acquisition parameters including flip angle, repetition time duration, echo time, and sampling patterns simultaneously. This multi-parameter optimization ensures that even with a reduced number of TR periods, the signal patterns maintain sufficient discrimination capability for accurate parameter estimation, balancing scan efficiency with measurement precision.
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 enables accurate quantitative MRI in the presence of inhomogeneous magnetic fields, reducing the need for highly homogeneous hardware, lowering costs, and enabling the development of lightweight, portable imaging devices while maintaining signal-to-noise ratio and reducing scan time.
Implementation Method 1
Magnetic resonance fingerprinting (MRF) is an imaging technique that enables quantitative mapping of tissue or other material properties based on random or pseudorandom measurements of the subject or object being imaged
Implementation Method 2
Examples of acquisition parameters that can be varied include flip angle, radio frequency (RF) pulse phase, TR, echo time (TE), and sampling patterns
Data Source
AI summary
Systems and methods for magnetic resonance fingerprinting (“MRF”) using highly differentiated trajectories that optimize differentiation between magnetic resonance signal patterns as a function of relaxation time(s) and static magnetic field homogeneity are described. Using the optimized acquisition parameters, MRF can be performed in the presence of inhomogeneous magnetic fields. Flip angle homogeneity can also be incorporated into the dictionary matching process to simultaneously estimate quantitative parameters of the subject and radio frequency coil transmission homogeneity profiles.