Nonlinear Spatial Encoding Gradients for Accelerated MRI
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Solution Overview
Problem
Conventional magnetic resonance imaging (MRI) techniques require long scan times due to inefficient use of orthogonal gradients, leading to reduced image resolution and increased costs with the use of multiple receive coils, which fail to effectively address the underlying encoding problem.
Innovation Solution
The use of complementary nonlinear magnetic gradient fields that are solutions to the Laplace equation, designed to optimize spatial encoding with receiver coil sensitivity profiles, allowing for efficient data acquisition and image reconstruction with fewer distortions and higher acceleration factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional orthogonal linear gradients are used in MRI, then the imaging process can be completed with standard procedures, but the scan times become relatively long
Solution Approach 1:
The patent changes the parameters of the gradient fields from conventional orthogonal linear gradients to nonlinear gradient fields that are complementary to receiver coil sensitivity profiles. This parameter change enables more efficient spatial encoding, allowing for reduced scan times while maintaining image quality through optimized gradient shapes rather than simply increasing gradient strength or number of coils
Solution Approach 2:
The patent introduces dynamic optimization by adjusting gradient shapes to be complementary to the specific receiver coil sensitivity profiles being used. This dynamic adaptation of gradient parameters to the receiver configuration enables efficient use of available hardware resources and optimizes the encoding process for each specific imaging setup
2Loss of time
If multiple receive coils are used to reduce scan time, then parallel imaging can be achieved, but the costs increase and image resolution may be reduced
Solution Approach 1:
The patent makes the gradient fields serve multiple functions by designing them to be complementary to receiver coil sensitivity profiles, simultaneously achieving efficient spatial encoding and optimized use of parallel imaging capabilities. This multi-functional approach allows the gradient system to compensate for the limitations of multiple coils, maintaining image resolution while enabling accelerated scanning
Solution Approach 2:
By changing from standard orthogonal gradients to nonlinear complementary gradients, the system optimizes the encoding efficiency to match the receiver coil configuration, allowing fewer coils to achieve the same imaging quality or enabling better resolution with the same number of coils through improved spatial encoding
3Quantity of substance
If conventional parallel imaging methods use orthogonal gradients, then data can be collected with multiple coils, but the information gathering from coil sensitivities becomes inefficient
Solution Approach 1:
The patent changes the gradient field parameters to be nonlinear and complementary to receiver coil sensitivity profiles, maximizing the information extracted from each coil's sensitivity distribution. This optimized parameter selection ensures that the gradient encoding and coil sensitivity profiles work together efficiently to gather maximum spatial information from the available receiver coils
Solution Approach 2:
The patent creates a complementary relationship between gradient fields and receiver coil sensitivity profiles, where the gradient pattern is designed to mirror or complement the spatial distribution of coil sensitivities. This copying of spatial relationships optimizes the encoding process by ensuring that regions with high coil sensitivity are efficiently encoded by corresponding gradient patterns
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 times, enables higher quality image acquisition in less time, and achieves maximum acceleration with minimal views, providing artifact-free images by leveraging the flexibility of gradient shapes to complement receiver coil performance.
Implementation Method 1
The Larmor frequency of a proton is proportional to the strength of the magnetic field. Consequently, if the applied magnetic field is generated with a known spatial gradient, then the Larmor frequency of protons will also have a known spatial localization.
Implementation Method 2
If the frequency of the RF pulse matches the Larmor frequency of protons in the volume, the pulse may induce a spin-flip transition of the protons from an aligned state to a higher-energy anti-aligned state.
Implementation Method 3
Magnetic resonance imaging (MRI) is a medical imaging technique based on the phenomenon of nuclear magnetic resonance (NMR).
Implementation Method 4
If the frequency of the RF pulse matches the Larmor frequency of protons in the volume, the pulse may induce a spin-flip transition of the protons from an aligned state to a higher-energy anti-aligned state.
Implementation Method 5
When the protons relax after the pulse, they will then emit RF signals at the Larmor frequency which can be detected with receiver coils.
Data Source
AI summary
In a method of magnetic resonance imaging, a set of nonlinear, mutually orthogonal magnetic gradient encoding fields are sequentially and separately generated in an imaging region [100]. Using multiple receiver coils having nonuniform sensitivity profiles, echo data representing signal intensities in the imaging region is sequentially acquired as the magnetic gradient encoding fields are sequentially generated [102]. A reconstructed image of the imaging region is computed from the acquired echo data [104], and the reconstructed image is then be stored and/or displayed on a display monitor [106].