MRI Tensor Field Mapping Without Fourier Reconstruction
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Solution Overview
Problem
Characterization of physical properties of a sample using non-invasive techniques like MRI is time-consuming, costly, and user-unfriendly due to long scan times and the confining environment of the magnet bore, which degrades the user experience and reduces throughput.
Innovation Solution
A system that applies an external magnetic field and RF pulse sequence, measures magnetization components, calculates predicted magnetization using a forward model, and iteratively modifies parameters until the difference between measured and predicted magnetization is minimized, without performing Fourier transforms, to determine parameters like density and relaxation times concurrently with measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional MRI scanning methods are used, then accurate physical parameter characterization is achieved, but scan time is excessively long and throughput is reduced
Solution Approach 1:
The system performs preliminary actions by applying multiple different RF pulse sequences and measuring multiple magnetization components before the main parameter calculation. This preliminary data collection enables concurrent determination of multiple parameters (T1, T2, proton density) without requiring sequential scanning, thereby reducing total scan time while maintaining measurement precision
Solution Approach 2:
The invention changes measurement parameters by acquiring multiple magnetization components (Mx, My, Mz) using different RF pulse sequences with varying flip angles and timing. This multi-parameter measurement approach allows the system to solve for multiple tissue parameters simultaneously through iterative optimization, achieving accurate characterization without extending scan time
2Measurement precision
If multiple measurements are performed for accurate parameter determination, then measurement precision improves, but the number of measurements increases scan time
Solution Approach 1:
The system maintains continuity of useful action by performing all necessary measurements and parameter calculations during a single continuous scanning session. The iterative optimization process continuously refines parameter estimates using accumulating measurement data without requiring pause or repositioning, maximizing productivity while ensuring precise parameter determination through multiple measurements
3Measurement precision
If conventional scanning protocols are used, then comprehensive tissue characterization is achieved, but user experience deteriorates due to long duration in magnet bore
Solution Approach 1:
The system performs preliminary data acquisition using efficient pulse sequences that capture essential magnetization information quickly. This preliminary action enables the majority of tissue characterization to be completed in reduced time, with iterative refinement occurring concurrently, thereby maintaining comprehensive characterization while significantly improving user experience by minimizing time in the magnet bore
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 reduces scan time, improves throughput, enhances user experience by minimizing time in the magnet bore, and increases the accuracy of scans, thereby reducing costs and errors.
Implementation Method 1
magnetic properties can be studied using magnetic resonance or MR (which is often referred to as 'nuclear magnetic resonance' or NMR), a physical phenomenon in which nuclei in a magnetic field absorb and re-emit electromagnetic radiation
Implementation Method 2
nuclei in a magnetic field absorb and re-emit electromagnetic radiation
Implementation Method 3
These nuclear spins may precess or rotate around the direction of the external magnetic field at an angular frequency (which is sometimes referred to as the 'Larmor frequency')
Implementation Method 4
the resulting dynamic response of the nuclear spins (such as the time-varying total magnetization) can provide information about the physical and material properties of a sample
Data Source
AI summary
During operation, a system may apply an external magnetic field and an RF pulse sequence to a sample. Then, the system may measure at least a component of a magnetization associated with the sample, such as MR signals of one or more types of nuclei in the sample. Moreover, the system may calculate at least a predicted component of the magnetization for voxels associated with the sample based on the measured component of the magnetization, a forward model, the external magnetic field and the RF pulse sequence. Next, the system may solve an inverse problem by iteratively modifying the parameters associated with the voxels in the forward model until a difference between the predicted component of the magnetization and the measured component of the magnetization is less than a predefined value. Note that the calculations may be performed concurrently with the measurements and may not involve performing a Fourier transform.