MRI K-space Blade Phase Encoding Order for Artifact Reduction
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Solution Overview
Problem
Magnetic resonance imaging (MRI) systems face issues with shading and blurring artifacts in reconstructed images due to conventional k-space data acquisition methods, which can lead to misdiagnosis and reduced image quality.
Innovation Solution
The method involves acquiring k-space data using a Periodically Rotated Overlapping Parallel Lines with Enhanced Reconstruction (PROPELLER) sampling scheme, where the phase encoding order of adjacent blades is reversed, and each blade is sampled with an asymmetric phase encoding order to reduce shading and blurring artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional k-space data acquisition methods are used, then image acquisition is straightforward, but shading and blurring artifacts occur in reconstructed images
Solution Approach 1:
The patent applies asymmetry by using different phase encoding directions for different blades in the PROPELLER sampling scheme. Specifically, odd-numbered blades use one phase encoding direction while even-numbered blades use the opposite phase encoding direction, creating an asymmetric sampling pattern that eliminates shading and blurring artifacts in the reconstructed MRI images
Solution Approach 2:
The patent implements periodic action through the rotational acquisition of multiple blades around the k-space center. The phase encoding direction alternates periodically between adjacent blades, creating a systematic periodic sampling pattern that covers the entire k-space while maintaining consistent signal magnitude across different regions
2Measurement precision
If signal magnitude fluctuations are not minimized, then acquisition process is simple, but image sharpness and accuracy are reduced
Solution Approach 1:
The patent uses asymmetric phase encoding orders for different blades to minimize signal magnitude fluctuations. By alternating the phase encoding direction between odd and even blades, the method creates an asymmetric sampling pattern that distributes signal magnitudes more uniformly across the imaging slice, thereby improving image sharpness and accuracy without requiring complex additional hardware
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 shading and blurring artifacts in MRI images, improving image sharpness and accuracy by minimizing signal magnitude fluctuations across the imaging slice, especially at tissue boundaries.
Implementation Method 1
the nuclear spins associated with the hydrogen nuclei in tissue water become polarized, wherein the magnetic moments associated with these spins become preferentially aligned along the direction of the magnetic field B0, resulting in a small net tissue magnetization along that axis
Implementation Method 2
The hydrogen nuclei are excited by a radio frequency signal at or near the resonance frequency of the hydrogen nuclei, which add energy to the nuclear spin system
Implementation Method 3
As the nuclear spins relax back to their rest energy state, they release the absorbed energy in the form of an RF signal
Data Source
AI summary
Various methods and systems are provided for acquiring a plurality blades of k-space data for magnetic resonance (MR) data acquisition. The plurality blades are arranged in a rotational manner around a center of the k-space. Each of the blades includes a plurality of parallel phase encoding lines indexed sequentially along a phase encoding direction of the blade. The phase encoding lines of each blade are sampled according to an asymmetric phase encoding order. The blade phase encoding orders of at least two adjacent blades are opposite to each other. This results in reducing shading and blurring artifacts in MRI images.