Radial k-space sampling for diffusion weighted MRI
Solution Overview
Problem
Current magnetic resonance imaging (MRI) techniques face challenges in reducing image acquisition time while minimizing motion artifacts and efficiently measuring diffusion, particularly in generating diffusion-weighted images.
Innovation Solution
The use of a radial k-space sampling method with diffusion gradient magnetic fields applied at varying angles and directions to form a radial k-space, allowing for the reconstruction of diffusion-weighted images using the Filtered Back Projection method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Cartesian k-space sampling is used for diffusion-weighted imaging, then complete diffusion information can be acquired, but image acquisition time is prolonged and motion artifacts increase
Solution Approach 1:
The patent segments the k-space sampling into multiple radial trajectories, where each trajectory acquires diffusion information along a specific direction. By dividing the complete k-space into multiple radial passes with different diffusion gradient directions, the system can acquire comprehensive diffusion information more efficiently than conventional Cartesian sampling, reducing total acquisition time while maintaining measurement accuracy.
Solution Approach 2:
The patent employs dynamic adjustment of diffusion gradient directions across multiple radial trajectories. Instead of using fixed gradient directions as in conventional methods, the system dynamically varies the diffusion gradient orientation to match each radial trajectory's sampling direction, enabling efficient acquisition of diffusion information in multiple directions without proportionally increasing scan time.
2Measurement precision
If multiple diffusion directions are acquired to improve diffusion measurement accuracy, then measurement precision improves, but acquisition time increases
Solution Approach 1:
The patent merges the acquisition of multiple diffusion directions with radial k-space sampling by aligning diffusion gradient directions with radial sampling angles. This combination allows simultaneous collection of spatial encoding information and diffusion direction information in a single scan, achieving multi-directional diffusion measurement without proportionally increasing acquisition time compared to conventional sequential multi-directional sampling.
Solution Approach 2:
The patent maintains continuous data acquisition throughout the radial sampling process, continuously collecting diffusion information across all directions without interruption. This continuous sampling approach ensures that diffusion information from multiple directions is acquired efficiently in a single uninterrupted scan, improving both measurement accuracy and imaging speed.
3Reliability
If longer acquisition time is used to reduce motion artifacts, then image quality improves, but productivity decreases
Solution Approach 1:
The patent employs radial (curved) sampling trajectories instead of straight Cartesian lines to traverse k-space. This radial approach naturally concentrates sampling density at the center of k-space where motion-related signal variations have greatest impact, providing motion artifact suppression while maintaining efficient acquisition. The curved radial paths enable faster coverage of critical k-space regions compared to conventional linear 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
This approach reduces image acquisition time and enables precise measurement of diffusion, facilitating faster and more accurate calculation of Apparent Diffusion Coefficient (ADC) maps.
Implementation Method 1
a gradient coil unit configured to form diffusion gradient magnetic fields
Implementation Method 2
Magnetic Resonance Imaging (MRI) refers to acquiring an image of the density and the physicochemical characteristics of body tissues based on the characteristics of an atomic nucleus by generating a nuclear magnetic resonance phenomenon
Data Source
AI summary
A magnetic resonance imaging apparatus and a diffusion-weighted image acquiring method form a radial k-space through a radial sampling and acquire a diffusion-weighted image from the radial k-space, with the diffusion-weighted image acquiring including receiving an echo signal generated from the subject, and forming a k-space having a plurality of sampling lines by sampling the echo signal that is received, wherein the directions of the diffusion gradient magnetic fields applied at the time of forming the sampling lines that compose the k-space to cross each other at two adjacent sampling lines.