MRI Multi-Contrast Acquisition via Echo Signal Segmentation
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Solution Overview
Problem
In MRI imaging using the radial sampling method, multi-echo sequences face challenges in maintaining image contrast due to the mixing of echo signals with different echo times near the center of the K-space, leading to deteriorated contrast and increased imaging time or reduced signal-to-noise ratio.
Innovation Solution
The method involves dividing echo signal groups into partial groups and reconstructing images with different contrasts using these partial groups, allowing for simultaneous acquisition of multiple contrast images without extending imaging time, while maintaining minimal echo signals and optimizing echo time distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If echo signals with different echo times are mixed near the center of the K-space in radial sampling method, then imaging time is reduced, but image contrast deteriorates
Solution Approach 1:
The patent divides the K-space into multiple regions (center region and peripheral regions) and applies different processing strategies to each. Echo signals are selectively assigned to different K-space regions based on their echo times, with early echo signals placed in the center region and later echo signals placed in peripheral regions. This segmentation allows the patent to maintain fast imaging through radial sampling while preserving image contrast by preventing mixing of different echo time signals in the contrast-critical center region.
2Reliability
If the number of echo signals is minimized to maintain signal-to-noise ratio, then the ability to acquire multiple contrast images is reduced
Solution Approach 1:
The patent segments the echo signal group into multiple partial echo signal groups based on echo time characteristics. Each partial group can be independently used to reconstruct images with different contrasts. This allows the patent to maintain a minimal total number of echo signals for optimal signal-to-noise ratio while still enabling multi-contrast acquisition by strategically assigning different subsets of echoes to different contrast images.
Solution Approach 2:
Different regions of the echo signal group are assigned different qualities or purposes based on their echo times. Early echo signals with higher signal intensity are allocated to specific contrast images requiring higher SNR, while later echo signals are allocated to other contrast images. This local quality differentiation allows optimal use of each echo signal while achieving multiple contrasts.
3Reliability
If echo signals are sampled radially to reduce body-movement artifacts, then robustness to body movement is improved, but image contrast deteriorates due to signal mixing
Solution Approach 1:
The patent maintains the radial sampling trajectory for robustness to body movement but segments the K-space into center and peripheral regions. By preventing mixing of different echo time signals in the center region through selective assignment, the patent preserves both the motion robustness of radial sampling and the image contrast that would otherwise be degraded by signal mixing.
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 improves image contrast and reduces imaging time by enabling the simultaneous acquisition of multiple contrast images with distinct contrasts, maintaining signal quality and spatial resolution.
Implementation Method 1
magnetic resonance imaging (hereinafter referred to as MRI) apparatus that obtains a tomographic image of an examination region in an object to be examined using nuclear magnetic resonance (hereinafter referred to as NMR) phenomenon
Data Source
AI summary
The contrast of an image obtained by using a multi-echo sequence with hybrid-radial sampling is improved by dividing echo signal groups of one or more blocks measured by executing the imaging using the multi-echo sequence, into a plurality of partial echo signal groups, each of which is used to reconstruct an image with different contrast from each other.