3D Spiral-In-Out MRI Encoding With Echo Reordering and Gradient Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Cartesian MRI data acquisition is inefficient in terms of k-space coverage, particularly at low-field systems, leading to prolonged scan times due to lower signal-to-noise ratio and the need for multiple signal averages to maintain image quality.
Innovation Solution
A method utilizing spiral-in-out encoding trajectories with variable flip angle RF series, spoiler gradient waveforms, and echo reordering, combined with gradient compensation and parallel imaging, to enhance k-space coverage and reduce scan time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Cartesian sampling is used for 3D MRI data acquisition, then image quality can be maintained with sufficient signal-to-noise ratio, but scan time becomes excessively long due to inefficient k-space coverage
Solution Approach 1:
The patent replaces conventional Cartesian (linear) k-space sampling trajectories with spiral trajectories that rotate and wind through k-space in a curved path. This spiral encoding approach allows more efficient coverage of k-space compared to linear Cartesian sampling, reducing scan time while maintaining image quality through optimized signal acquisition along the spiral path
2Device complexity
If low-field MRI systems are used to reduce cost and increase accessibility, then hardware complexity decreases, but signal-to-noise ratio deteriorates requiring multiple signal averages that double scan time
Solution Approach 1:
The patent implements continuous spiral-in-out trajectories that efficiently sample k-space without the need for repeated signal averages. The variable flip angle scheme maintains consistent signal levels throughout the echo train, enabling continuous data acquisition that eliminates the time penalty associated with multiple averages required in conventional low-field Cartesian imaging
3Measurement precision
If high-isotropic spatial resolution is prescribed to improve diagnostic accuracy, then measurement precision increases, but k-space coverage efficiency decreases leading to longer scan times
Solution Approach 1:
The spiral trajectories provide superior k-space coverage efficiency compared to Cartesian grids, especially for high-resolution 3D imaging. The rotating spiral path allows more uniform and efficient sampling of high-frequency k-space regions, enabling high-isotropic spatial resolution to be achieved with shorter scan times than conventional Cartesian sampling
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
The method significantly reduces scan time and improves image quality by efficiently covering k-space, maintaining signal integrity, and correcting for concomitant gradient effects, even at low-field strengths.
Implementation Method 1
magnetic resonance imaging (MRI) data
Implementation Method 2
applying a spoiler gradient waveform along the spoiler gradient direction
Data Source
AI summary
Acquiring 3D MRI data using spiral-in-out encoding trajectories includes calculating a variable flip angle RF series for use as refocusing pulses, wherein the RF series includes a plurality of refocusing RF pulses. A spoiler gradient waveform is applied along the spoiler gradient direction, wherein the computer alternately adds and subtracts partition encoding waveforms to the spoiler gradient waveform. The method reads MRI data from each encoding step during an MRI sequence. The MRI sequence inserts a spiral-in gradient before a first refocusing RF pulse from the RF sequence, overlaps a pre-winder lobe for the encoding trajectory with the spoiler gradient waveform having the partition encoding waveforms added therein, and overlaps a rewinder lobe for the encoding trajectory with the spoiler gradient waveform having the partition encoding waveforms subtracted there from.