Magnetic Field Modulation for MRT Imaging Speed
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Solution Overview
Problem
Conventional MRT imaging techniques are time-consuming and face limitations in clinical applications due to the need for rapid switching of strong linear gradients, which can affect the object being imaged, and require complex field shaping for non-unidirectional spatial encoding.
Innovation Solution
The method employs a static magnetic field with a spatially restricted, time-varying magnetic modulation field applied during the readout period, providing locally specific frequency modulation to the MR signals, allowing for additional spatial encoding without the need for sharp delimitations between sections, and utilizing this modulation for accelerated imaging and improved signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If strong linear gradients are rapidly switched for spatial encoding, then imaging speed is improved, but the object being imaged is affected by altering magnetic fields
Solution Approach 1:
The patent changes the parameter of magnetic field gradients from strong linear gradients to weak non-unidirectional gradients. This allows spatial encoding to be achieved without the harmful effects of rapidly switching strong fields, thus resolving the contradiction between imaging speed and object safety
Solution Approach 2:
The patent replaces the conventional gradient switching mechanism with a magnetic field modulation approach using localized coils. Instead of mechanically switching strong gradients, the system uses modulated magnetic fields from multiple localized sources to achieve spatial encoding, eliminating the harmful rapid field changes
2Object-affected harmful factors
If non-unidirectional non-bijective spatial encoding magnetic fields are used, then the need for strong gradient switching is avoided, but complex field shaping is required
Solution Approach 1:
The patent divides the magnetic field generation into multiple localized coils distributed throughout the imaging volume. Each coil generates a simple modulation field, and the combined effect achieves the desired non-unidirectional encoding. This segmentation avoids the need for each individual coil to create complex field patterns
Solution Approach 2:
The patent uses identical localized coils for both excitation and signal reception functions. These same coils also generate the modulation fields for spatial encoding. This multi-functionality reduces device complexity by eliminating the need for separate gradient coil systems
3Productivity
If parallel imaging with multiple RF receive coils is used, then imaging speed is accelerated, but the local sensitivity profile requires complex coil arrangements
Solution Approach 1:
The patent merges the functions of spatial encoding and signal reception into a single set of localized coils. Instead of having separate gradient coils and receive coils, the same coils perform both functions, simplifying the overall system architecture while maintaining parallel imaging capabilities
Solution Approach 2:
The patent introduces temporal modulation to the magnetic fields generated by localized coils. By dynamically modulating the field strength and frequency of individual coils during the imaging sequence, the system achieves both spatial encoding and parallel imaging functionality without requiring complex static coil arrangements
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 faster MR imaging with improved signal-to-noise ratio and reduced complexity in creating local gradient fields, allowing for accelerated data acquisition and enhanced image reconstruction quality.
Implementation Method 1
a locally specific frequency modulation of magnetization is created by applying a magnetic modulation field to the object
Implementation Method 2
a spatially restricted, time-varying magnetic modulation field... providing locally specific frequency modulation to the MR signals
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~5D
AI summary
A method of magnetic resonance (MR) tomography imaging an object 1 comprises arranging the object in a static magnetic field, subjecting the object to at least one radiofrequency pulse and magnetic field gradients for creating spatially encoded MR signals, acquiring MR signals, and reconstructing an object image utilizing the spatial encoding of the MR signals, wherein, during the acquiring step, the MR signals are subjected to a locally specific frequency modulation by means of at least one spatially restricted, time-varying magnetic modulation field with a component parallel to the static magnetic field, and the step of reconstructing the object image further utilizes the frequency modulation for obtaining spatial information from the spatially encoded MR signals. An MR imaging device 100 includes an MR scanner 110 with a magnetic field modulation source device 114 for creating a spatially restricted, time-varying magnetic modulation field, a control device 120 and a reconstruction device 130 for reconstructing the object image by utilizing a frequency modulation of collected MR signals for obtaining spatial image information.