Interleaved Motion Encoding for Efficient 3D Magnetic Resonance Elastography
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Solution Overview
Problem
Current volumetric 3D Magnetic Resonance Elastography (MRE) sequences are inefficient due to missing out on higher SNR afforded by 3D acquisitions and require substantial time for data collection, leading to motion-related ghosting artifacts.
Innovation Solution
A method and device for MRE that employs a periodical vibration signal with synchronized motion encoding gradients and a reference scan, allowing for efficient 3D slab-selective Magnetic Resonance Imaging with phase corrections, enabling rapid and reliable estimation of tissue stiffness and viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If 3D MRE sequences are acquired in 2D slices, then the acquisition time is reduced and motion artifacts are minimized, but the signal-to-noise ratio (SNR) is degraded
Solution Approach 1:
The patent transitions from 2D slice-by-slice acquisition to true 3D volumetric acquisition by utilizing slab-selective radio frequency pulses and three-dimensional gradient encoding. This dimensional change enables simultaneous excitation and encoding of multiple slices, achieving high SNR through volumetric data collection while maintaining acceptable acquisition times through optimized pulse sequences and parallel imaging techniques.
2Measurement precision
If longer acquisition time is used for 3D MRE, then higher SNR is achieved, but motion-related ghosting artifacts increase
Solution Approach 1:
The patent employs periodic vibration excitation at standardized frequencies (e.g., 60 Hz) with corresponding periodic sampling of the MR signal. This periodic action synchronizes the acquisition with the mechanical vibration, enabling coherent signal accumulation that enhances SNR while the predictable timing pattern facilitates motion correction algorithms to reduce ghosting artifacts from physiological movements.
Solution Approach 2:
The patent implements continuous vibration excitation throughout the entire 3D acquisition period, maintaining constant mechanical stimulation of the tissue. This continuous action ensures that the propagating shear waves are always present and can be continuously sampled, maximizing signal strength and SNR without requiring repeated excitations that would extend total acquisition time and increase motion artifacts.
3Measurement precision
If standard MRE sequences are used, then tissue stiffness can be estimated, but simultaneous assessment of inflammation is not achieved
Solution Approach 1:
The patent implements a multi-functional MRE sequence that simultaneously measures multiple tissue rheological properties including stiffness (elastic modulus), viscosity (loss modulus), and inflammation markers. By acquiring multi-directional vibration data at multiple frequencies and analyzing both magnitude and phase information, the sequence provides comprehensive tissue characterization in a single examination, eliminating the need for separate scans for different pathological assessments.
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 rapid and reliable estimation of tissue stiffness and viscosity with reduced acquisition time and minimized ghosting artifacts, facilitating accurate assessment of liver fibrosis and inflammation in a single breath-hold.
Implementation Method 1
providing a periodical vibration signal for exciting mechanical vibrations with a vibration period
Implementation Method 2
in each sampling period three motion encoding gradients and one reference scan without motion encoding are performed for magnetic resonance acquisition
Data Source
AI summary
In a method for performing Magnetic Resonance Elastography (MRE) more efficiently may include providing a periodical vibration signal for exciting mechanical vibrations within an object to be examined with a vibration period, sampling the vibration signal with a sampling period corresponding to a natural number including zero of vibration periods plus a fixed time delay, and performing three motion encoding gradients for magnetic resonance acquisition in each sampling period. The fixed time delay multiplied with a sampling number may be equal to the vibration period. The sampling number may be a natural number greater than two.