Open Field-Cycling MRI with Nonlinear Encoding for Compact Imaging
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Solution Overview
Problem
Conventional MRI systems are limited by the need for a spatially uniform main magnetic field, which constrains design opportunities, are expensive, and are not suitable for claustrophobic patients or obese individuals, requiring expert analysis that can be subjective.
Innovation Solution
MRI systems using a field-cycling magnet that cycles between non-uniform B0 fields, non-planar radiofrequency coils, and DC gradients for non-linear spatial encoding, allowing for customizable and compact designs that can image specific anatomies with high sensitivity and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a spatially uniform main magnetic field is used in conventional MRI systems, then imaging quality is maintained, but the system becomes large, expensive, and unsuitable for claustrophobic or obese patients
Solution Approach 1:
The patent changes the fundamental parameter of the magnetic field from uniform to non-uniform, and from static to time-varying (field-cycling between different field strengths). This allows the system to achieve adequate imaging quality without requiring the large, expensive superconducting magnets that produce uniform fields, thereby resolving the contradiction between imaging quality and device complexity
Solution Approach 2:
Instead of using a uniform field and adding gradients to create spatial encoding, the patent inverts the approach by using inherently non-uniform fields and achieving spatial encoding through field-cycling and specialized gradient techniques. This inversion allows compact system design while maintaining imaging capability
2Reliability
If superconducting magnets with uniform fields are built, then MRI imaging capability is achieved, but manufacture and operational cost becomes very high
Solution Approach 1:
The patent replaces expensive, complex superconducting magnets with simpler, cheaper resistive electromagnets that can be rapidly cycled. These less durable but much cheaper magnets enable MRI imaging capability without the high manufacture and operational costs of superconducting systems, resolving the contradiction between reliability and ease of manufacture
Solution Approach 2:
The patent employs periodic field-cycling between different magnetic field strengths to achieve both magnetization and imaging in a time-varying manner. This periodic action allows the use of cheaper resistive magnets instead of expensive superconducting magnets, reducing manufacture and operational costs while maintaining imaging capability
3Measurement precision
If conventional closed MRI design is used, then uniform field requirement is met, but accessibility for claustrophobic patients and medical interventions is limited
Solution Approach 1:
The patent inverts the conventional approach by abandoning the closed magnet design and uniform field requirement, using open magnet configurations with non-uniform fields instead. This inversion enables patient accessibility and medical intervention while achieving imaging capability through alternative physical principles
Solution Approach 2:
By changing the magnetic field parameter from uniform to non-uniform and implementing field-cycling, the patent enables the use of open magnet designs that provide patient accessibility and facilitate medical interventions, resolving the contradiction between field uniformity and ease of operation
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
Enables compact, cost-effective MRI systems that can be used in various settings, including doctor's offices, with improved imaging capabilities for claustrophobic and obese patients, and facilitates AI-assisted diagnosis.
Implementation Method 1
a first component containing an open, field-cycling magnet configured to produce and cycle between a first non-uniform B0 and a second non-uniform B0
Implementation Method 2
radiofrequency (RF) coils with non-planar configuration, a non-horizontal configuration, or both, geometrically configured to receive signal from spins precessing perpendicularly to the non-uniform B0 magnetic field
Data Source
AI summary
Described herein are compact MRI systems having (i) an open, field-cycling magnet configured to produce and cycle between a first and second non-uniform B0 different from the first non-uniform B0, and (ii) a second component configured to produce a nonlinear spatial encoding gradient. Importantly, the open, field-cycling magnet and the spatial encoding gradients are customized to a specific imaging application. In particular, the second component contains one or several nonlinear DC gradient coils for spatial encoding. It also contains one or several a radiofrequency coils geometrically configured to have a non-planar configuration. Lastly, both the RF coils and DC encoding gradients are tailored specifically to the first non-uniform B0 magnetic field, the second non-uniform B0 magnetic field, or both. Artificial intelligence models trained to read imaging data can be incorporated as a component of the MRI systems. Also described are methods of using the disclosed MRI systems.