K-Space Density Distribution for MR Image Artifact Reduction
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Solution Overview
Problem
Existing MR image reconstruction methods using compressed sensing undersampling result in artifacts due to uniform k-space density, which complicates echo time compliance and image quality.
Innovation Solution
The method involves acquiring MR data with multiple echo trains, where k-space is divided into two halves with different densities, allowing for pseudo-random distribution of k-space lines, ensuring the k-space center is scanned at a predetermined echo time, and using iterative methods for reconstruction without phase correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If uniform density k-space sampling is used in compressed sensing, then the reconstruction algorithm can be simplified, but artifacts occur in the reconstructed MR image
Solution Approach 1:
The patent applies local quality by differentiating the sampling density across different regions of k-space. Specifically, the first k-space half (from center to edge in one direction) uses a first density while the second k-space half uses a second density, creating non-uniform sampling patterns that reduce artifacts while maintaining reconstruction feasibility
2Productivity
If k-space is undersampled to reduce acquisition time, then productivity increases, but echo time compliance becomes difficult to maintain
Solution Approach 1:
The patent segments k-space into multiple regions (first k-space half and second k-space half) with different sampling densities. This segmentation allows the k-space center to be sampled at the required echo time while other regions use reduced sampling densities, maintaining both echo time compliance and acquisition speed
3Object-generated harmful factors
If random k-space sampling is used to reduce artifacts, then image quality improves, but the echo time condition cannot be satisfied
Solution Approach 1:
The patent introduces asymmetry in k-space sampling by assigning different densities to different k-space halves. The first k-space half has a first density while the second k-space half has a second density, creating an asymmetric sampling pattern that satisfies echo time requirements while reducing artifacts through non-uniform distribution
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 artifacts in MR image reconstruction, enables uniform k-space scanning, and complies with echo time conditions, improving image quality and reducing computational time.
Implementation Method 1
a magnetic resonance system (5) for radiating an RF excitation pulse to excite nuclear spins in a two-dimensional or three-dimensional volume segment of a subject O)
Implementation Method 2
a gradient field system (3) for generating gradient fields
Data Source
AI summary
In a method to operate a magnetic resonance (MR) system to acquire MR data, an RF excitation pulse is radiated followed by repeated, chronologically sequential implementation of the following steps in order to respectively acquire the MR data of an echo train. A refocusing pulse is radiated, a phase coding gradient is activated, and an additional magnetic field gradient for spatial coding is activated in a direction that is orthogonal to the direction of the phase coding gradient in order to read out the MR data of a k-space line. A k-space line in the k-space center is acquired at a predetermined echo time. A first half of k-space is acquired by entering data into k-space lines of the respective echo train, the data being acquired before the echo time. A second half of k-space is acquired by entering data into k-space lines of the respective echo train, this data having been acquired after the echo time. The k-space lines in the first half of k-space have a first density while the k-space lines in the second half of k-space have a second density that differs from the first density.