3D Radial MRE Pulse Sequence for Dynamic Tissue Stiffness Imaging
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Solution Overview
Problem
Current Magnetic Resonance Elastography (MRE) techniques struggle to generate high spatial and temporal resolution images of dynamic tissue stiffness, particularly in applications involving muscle activation, cardiac imaging, and functional brain imaging, due to limitations in capturing dynamic stiffness changes and motion artifacts.
Innovation Solution
A method using a magnetic resonance imaging (MRI) system that acquires data while providing a vibratory stimulus to induce motion within the tissue. The data is sampled using a pulse sequence that radially rotates planes about a phase encoding axis and includes motion encoding gradients to encode motion into the image phase, followed by iterative image reconstruction to generate mechanical property maps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MRE pulse sequences are used to acquire static tissue stiffness images, then spatial resolution can be maintained, but temporal resolution deteriorates due to inability to capture dynamic stiffness changes
Solution Approach 1:
The k-space sampling is divided into multiple radial planes that are rotated and sampled separately. Each radial plane captures a portion of the k-space data, and by acquiring multiple such planes sequentially, the system achieves both high spatial resolution (through complete k-space coverage) and improved temporal resolution (through accelerated acquisition). The segmentation of k-space into radial segments enables parallel processing and faster reconstruction.
Solution Approach 2:
The pulse sequence employs periodic radial rotation of sampling planes around the phase encoding axis, where each plane is sampled at regular intervals. This periodic sampling strategy allows for efficient k-space coverage while maintaining temporal resolution, as the repeating pattern enables predictable and optimized data acquisition cycles that can be reconstructed dynamically.
2Loss of time
If faster imaging sequences are used to improve temporal resolution, then dynamic stiffness changes can be captured, but spatial resolution deteriorates due to reduced sampling density
Solution Approach 1:
The patent transitions from conventional 2D Cartesian k-space sampling to 3D radial k-space sampling. By adding the radial dimension and rotating sampling planes through 3D space, the system achieves more efficient k-space coverage. This dimensional change allows for accelerated acquisition (improved temporal resolution) while maintaining or even enhancing spatial resolution through the geometric advantages of radial sampling patterns.
Solution Approach 2:
The system performs preliminary radial sampling of multiple k-space planes before final image reconstruction. By pre-acquiring and storing the radially sampled data from multiple planes, the system prepares the complete dataset needed for high-resolution reconstruction, enabling both fast temporal sampling and high spatial fidelity without compromising either parameter during the actual imaging process.
3Measurement precision
If radial sampling of multiple k-space planes is performed, then both spatial and temporal resolution improve, but device complexity increases due to sophisticated pulse sequence requirements
Solution Approach 1:
The radial sampling pulse sequence is designed to be multi-functional, serving both high-resolution spatial encoding and accelerated temporal sampling within a single unified framework. The same radial rotation mechanism and sampling strategy simultaneously achieve complete k-space coverage for spatial resolution and rapid data acquisition for temporal resolution, eliminating the need for separate specialized sequences and reducing overall system complexity.
Solution Approach 2:
The patent replaces complex mechanical multi-coil array systems with a more streamlined radial sampling approach. By using sophisticated k-space sampling trajectories and iterative reconstruction algorithms, the system achieves high-resolution dynamic imaging without requiring complex hardware configurations, thereby reducing device complexity while maintaining or improving imaging performance.
4Loss of information
If motion encoding gradients are applied to each echo planar readout, then motion within tissue is encoded into image phase, but data acquisition complexity increases
Solution Approach 1:
The motion encoding gradients are merged with the radial sampling pulse sequence structure. Instead of treating motion encoding as a separate complex process, the gradients are integrated into the radial readout framework, where the same pulse sequence elements that perform spatial encoding also perform motion encoding. This merging reduces overall system complexity while maintaining accurate motion capture capabilities.
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 the generation of high-resolution, dynamic mechanical property maps that effectively capture tissue stiffness changes over time, reducing motion artifacts and expanding the applicability of MRE in dynamic imaging applications.
Implementation Method 1
a vibratory stimulus is provided to the subject in order to induce motion within a tissue of the subject
Implementation Method 2
motion encoding gradients that are generated before each echo planar readout in order to encode the motion within the tissue into an image phase of the data
Data Source
AI summary
Described here are systems and methods for a robust magnetic resonance elastography (“MRE”) imaging platform for rapid dynamic 3D MRE imaging. The imaging platform includes an MRE pulse sequence and advanced image reconstruction framework that work synergistically in order to greatly expand the domains where MRE can be deployed successfully.