Spin-Echo MRI Slice Excitation for Blood Flow Artifact Reduction
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Solution Overview
Problem
Existing MRI techniques using spin echo pulse sequences suffer from increased blood flow artifacts due to blood flowing into the imaging plane, which is not effectively addressed by existing flow compensation methods.
Innovation Solution
The excitation width of the 90° pulse is extended to the downstream side of the imaging plane, aligning with the direction of blood flow, and the 180° pulse is applied within the same range, while adjusting the excitation profile to minimize blood magnetization in the imaging plane and subsequent cross sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the excitation width of the 90° pulse is extended to both sides of the imaging plane, then the flow artifact in the next cross section is reduced, but the flow artifact in the current imaging plane increases due to blood with extra magnetization flowing into the imaging plane
Solution Approach 1:
The patent applies asymmetry by extending the excitation width of the 90° pulse asymmetrically - to the downstream side only, rather than equally to both sides. This asymmetric extension ensures that blood with extra magnetization is excited in the downstream region, preventing it from flowing into the imaging plane and causing artifacts, while avoiding the harmful effect of exciting upstream blood that would increase flow artifacts in the current imaging plane.
Solution Approach 2:
The patent applies local quality by making the excitation profile non-uniform - the excitation width is extended specifically in the downstream direction where blood flow would cause problems, while maintaining normal excitation in the upstream direction. This localized adjustment of excitation parameters targets the specific problem area (downstream blood flow) without adversely affecting the imaging plane quality.
2Reliability
If the excitation width is extended to prevent blood flow interference, then image quality in subsequent cross sections improves, but magnetization from excited regions does not contribute to forming images of the imaging plane
Solution Approach 1:
The asymmetric extension of excitation width to the downstream side only ensures that the imaging plane receives appropriate magnetization for image formation, while the downstream region receives the extended excitation to prevent blood flow interference in subsequent imaging. This asymmetric design resolves the contradiction by directing the extended excitation away from the imaging plane.
Solution Approach 2:
The local quality principle is applied by maintaining standard excitation parameters in the imaging plane region to ensure proper image formation, while extending excitation only in the downstream direction where it is needed to prevent blood flow artifacts. This localized differentiation ensures both image quality and artifact reduction.
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 significantly reduces blood flow artifacts across multiple cross sections, ensuring clearer imaging results by minimizing the generation of spin echoes from blood flowing into the imaging plane.
Implementation Method 1
nuclear magnetic resonance signals generated from an examination subject caused by nuclear magnetic resonance are collected to create an image of the examination subject
Implementation Method 2
gradient magnetic field pulses for adding position information to the nuclear magnetic resonance signals
Data Source
AI summary
Preventing blood flow artifacts from being increased in an imaging plane allows reduction of the blood flow artifacts in the cross section subsequently excited. In the imaging using a spin-echo (SE) pulse sequence, an excitation width of a 90° pulse is extended from an imaging plane to one side. This one side indicates a downstream side of the blood flow with respect to a vessel of interest. In imaging multiple slices, the order of measuring the multiple imaging slices is set along the direction in which the width is extended.