Spiral-Ring MRI Diffusion Imaging With Magnitude Stabilizers
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Solution Overview
Problem
Conventional Cartesian sampling in MRI data acquisition is time-consuming due to inefficient k-space coverage, especially in low-field systems, which results in a lower signal-to-noise ratio and increased scan time, necessitating multiple signal averages to maintain clinically acceptable image quality.
Innovation Solution
A computer-implemented method using a diffusion preparation software component and a spiral ring echo readout software component, which applies diffusion gradients, magnitude stabilizer gradients, rephasing gradients, and dephasing gradients to acquire MRI data efficiently, reducing artifacts and improving image quality through spiral-ring trajectories and magnitude stabilizers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Cartesian sampling is used for MRI data acquisition, then complete k-space coverage is achieved, but scan time becomes excessively long
Solution Approach 1:
The patent applies spiral-ring trajectories instead of conventional Cartesian sampling lines. The spiral rings efficiently cover k-space by following curved paths that prioritize central k-space regions first, then progressively sample peripheral regions. This curved sampling approach reduces scan time while maintaining adequate k-space coverage for diagnostic image quality.
2Reliability
If multiple signal averages are applied in low-field systems, then image quality is maintained, but total scan time increases at least double
Solution Approach 1:
The single-shot acquisition method acquires all necessary diffusion-weighted images continuously in one shot without requiring multiple signal averages. The spiral-ring trajectory enables complete k-space sampling for all diffusion directions and b-values within a single continuous acquisition window, eliminating the need for repeated scans and signal averaging that would otherwise be necessary in low-field systems.
3Manufacturing precision
If high-isotropic spatial resolution is prescribed, then detailed anatomical information is obtained, but k-space coverage efficiency decreases
Solution Approach 1:
The spiral-ring trajectories are specifically designed to efficiently sample k-space at high resolutions. The curved paths allow denser sampling in the central k-space region which corresponds to fine anatomical details, while progressively sampling peripheral regions for overall image structure. This enables high-isotropic spatial resolution without the inefficiency of conventional Cartesian sampling.
4Loss of time
If single-shot acquisition is used, then scan time is reduced, but image quality may deteriorate due to lower signal-to-noise ratio
Solution Approach 1:
The spiral-ring trajectory concentrates sampling density in central k-space regions during the single-shot acquisition, which corresponds to low spatial frequencies containing the majority of signal energy. This prioritized sampling strategy maximizes signal-to-noise ratio for the most important image information within the constrained single-shot time window, maintaining diagnostic image quality despite the reduced 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
The method significantly reduces scan time and improves image quality by minimizing artifacts and maintaining clinically acceptable image quality with reduced signal-to-noise ratio, especially in low-field systems, while maintaining geometric fidelity and providing accurate diffusion-weighted images.
Implementation Method 1
applying at least a first diffusion gradient and a last diffusion gradient along a selected direction
Implementation Method 2
applying a magnitude stabilizer gradient, along said selected direction, after the last diffusion gradient
Implementation Method 3
applying a rephasing gradient along said selected direction after a refocusing RF pulse
Implementation Method 4
applying a dephasing gradient along said selected direction prior to a subsequent refocusing RF pulse
Data Source
AI summary
Acquiring magnetic resonance imaging (MRI) data includes steps of using a computer to implement software program steps in a diffusion preparation software component and a spiral ring echo readout software component. The method implements the diffusion preparation software component by (i) applying at least a first diffusion gradient and a last diffusion gradient along a selected direction; and (ii) applying a magnitude stabilizer gradient, along said selected direction, after the last diffusion gradient. The method implements the spiral ring echo readout software component by (i) applying a rephasing gradient along said selected direction after a refocusing RF pulse; (ii) applying a dephasing gradient along said selected direction prior to a subsequent refocusing RF pulse; and (iii) acquiring spiral ring echo readout data between the refocusing RF pulse and the subsequent refocusing RF pulse.