MRI B1 Shimming Using Patient-Specific Projection Mapping
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Solution Overview
Problem
Current B1 field mapping methods in MRI are impractically lengthy, leading to prolonged scan times and potential misdiagnosis due to non-uniform RF excitation caused by dielectric properties of the human body under high B0 fields.
Innovation Solution
A patient-specific B1 field shimming method using 1D projection data acquisition to determine optimal shimming parameters {A, φ} based on patient anatomy, reducing scan time to approximately one second by utilizing projection data instead of Cartesian encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional B1 mapping approaches are used to achieve uniform B1 field distribution, then B1 field homogeneity is improved, but scan time is significantly prolonged
Solution Approach 1:
The patent extracts only the essential information needed for B1 shimming by acquiring data along one or more projections rather than performing complete B1 mapping. This selective extraction of critical information maintains shimming effectiveness while dramatically reducing the measurement time from tens of seconds to approximately one second.
Solution Approach 2:
Instead of performing full B1 mapping coverage, the patent uses partial action by acquiring projection data along limited orientations. This partial measurement approach provides sufficient information for determining shimming parameters without the time cost of complete mapping, achieving the desired B1 homogeneity with reduced scan time.
2Manufacturing precision
If higher static magnetic field strengths (3T and above) are used to improve image resolution, then spatial and contrast resolution are enhanced, but RF field non-uniformity increases due to complex RF behavior and dielectric properties
Solution Approach 1:
The patent implements feedback by acquiring actual B1 projection data from the patient and using this measured information to determine patient-specific shimming parameters. This feedback loop allows the system to compensate for the complex RF behavior and dielectric effects that cause non-uniformity at high field strengths, ensuring reliable B1 homogeneity while maintaining the resolution benefits of 3T and above scanners.
3Manufacturing precision
If patient-specific B1 shimming is performed using conventional methods, then B1 field uniformity is improved, but the complexity of the procedure increases
Solution Approach 1:
The patent changes the measurement parameters from complete spatial mapping to projection-based sampling along specific orientations. This parameter change simplifies the acquisition procedure while maintaining the ability to determine patient-specific shimming parameters, reducing procedural complexity without sacrificing B1 field uniformity improvement.
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
Achieves rapid and accurate B1 field homogenization, improving MRI image quality and reducing the risk of misdiagnosis by minimizing dielectric artifacts, while maintaining clinical information integrity.
Implementation Method 1
RF pulses generated by an RF transmitter cause perturbations to the local magnetic field, and RF signals emitted by the nuclear spins are detected by an RF receiver
Implementation Method 2
RF pulses generated by an RF transmitter cause perturbations to the local magnetic field
Implementation Method 3
the dielectric properties of the human body can cause local perturbations to the B1 fields, resulting in non-uniform excitation
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(d)
Figure 3
AI summary
A shimming method according to an embodiment is a shimming method (400) for performing patient-specific Bl field shimming in a magnetic resonance imaging system. The method (400) includes obtaining (410) patient information of a patient to be imaged by the magnetic resonance imaging system. The method (400) further includes determining (420) an orientation of a projection based on the obtained patient information. The method (400) also includes acquiring (430) Bl projection data, using the magnetic resonance imaging system, along the determined orientation of the projection. In addition, the method (400) includes determining (440) a set of Bl shimming parameters based on the acquired Bl projection data.