Single-Shot EPI MRE Pulse Sequence for Rapid 3D Displacement
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Solution Overview
Problem
Clinical application of brain magnetic resonance elastography (MRE) is limited by the inability to rapidly capture three-dimensional, full vector MRE displacement fields, hindering accurate diagnosis and prognosis.
Innovation Solution
A single-shot, spin echo rapid motion encoding gradient sequence using echo-planar imaging (EPI) readout is developed to acquire MRE data, enabling the measurement of three-dimensional, full vector displacement fields in various organs, including the brain, without the need for extensive off-line image processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MRE sequences are used, then measurement precision of tissue displacement is improved, but acquisition time increases and productivity decreases
Solution Approach 1:
The patent segments the MRE measurement process into multiple frequency components, acquiring displacement fields at different vibration frequencies separately and combining them through image fusion. This allows each frequency component to be measured with high precision using optimized sequences, while the overall acquisition time is reduced by parallel processing and selective frequency sampling.
Solution Approach 2:
The patent applies preliminary motion encoding gradients during the MRI pulse sequence to pre-encode the mechanical vibration displacements into phase information. By incorporating the motion encoding gradients into the readout sequence itself rather than as a separate preprocessing step, the system achieves rapid capture of displacement fields without sacrificing measurement precision.
2Measurement precision
If three-dimensional full vector MRE displacement fields are captured, then diagnostic accuracy is improved, but device complexity and processing requirements increase
Solution Approach 1:
The patent extracts only the essential displacement information along the direction of mechanical vibration by using motion encoding gradients oriented perpendicular to the vibration direction. This extraction approach captures the full vector displacement field needed for diagnostic accuracy while eliminating redundant data processing requirements, thereby reducing computational complexity.
Solution Approach 2:
The patent designs a universal MRE pulse sequence that can capture displacement fields in multiple directions and at multiple frequencies using the same basic sequence structure. By making the sequence multi-functional through configurable gradient directions and frequency parameters, the system achieves comprehensive three-dimensional characterization without requiring separate specialized sequences for each measurement type.
3Productivity
If rapid image acquisition is implemented, then productivity is improved, but image quality and measurement precision may deteriorate
Solution Approach 1:
The patent implements continuous data acquisition during the entire duration of mechanical vibration by using a single-shot echo-planar imaging readout. The continuous gradient echo sequence captures displacement information throughout the vibration cycle without gaps, maintaining measurement precision while achieving rapid acquisition. The useful action of data collection continues uninterrupted from the start to the end of the vibration period.
Solution Approach 2:
The patent optimizes multiple sequence parameters including gradient strength, echo time, and repetition time to achieve the fastest possible acquisition speed while maintaining adequate signal-to-noise ratio for precise displacement measurement. By carefully adjusting these parameters and using parallel imaging techniques, the system captures high-quality MRE data in a single shot without requiring multiple averages that would increase acquisition time.
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 allows for rapid and accurate detection of diseased states, improving diagnostic accuracy and treatment planning by providing high-quality images and quantitative estimates of tissue stiffness.
Implementation Method 1
A motion encoding gradient is generated that is synchronized with the mechanical agitation
Implementation Method 2
magnetic resonance elastography (MRE) displacement fields
Data Source
AI summary
Magnetic resonance elastography (MRE) is an imaging technique for estimating the stiffness of tissues non-invasively. Shear waves are generated via external mechanical actuation and the tissue imaged with a specially designed MR pulse sequence. The resulting images are used to calculate the underlying properties. The application provides methods for acquiring MRE data using a single shot, echo planar imaging readout. The purpose of the developed sequence is to acquire MRE data using a single-shot, echo-planar imaging readout, avoiding to need for off-line image processing.