Decentralized K-Space Acquisition for MRI Artifact Reduction
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Solution Overview
Problem
Magnetic resonance data acquisition artifacts occur when examination subjects extend into the edge regions of the tunnel opening, leading to incorrect spatial coding of signals and increased measurement time, particularly in sagittal acquisitions like the lumbar spinal column, due to decreased gradient fields.
Innovation Solution
Acquiring magnetic resonance data multiple times from a selected partial region in k-space, with this region decentralized relative to the center of k-space, using techniques like three-dimensional turbo spin echo sequences and SPACE sequences to reduce artifacts and measurement time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entirety of k-space is scanned repeatedly to avoid artifacts, then artifact reduction is achieved, but measurement time increases by up to 40%
Solution Approach 1:
The patent divides k-space into multiple regions (first region, second region, third region) and applies different scanning strategies to each region. The first and third regions are scanned once, while the second region is scanned multiple times to reduce artifacts. This segmentation allows artifact reduction in critical areas without requiring repeated scanning of the entire k-space, thereby limiting measurement time increase.
Solution Approach 2:
The patent applies different quality levels of scanning to different regions of k-space. The second region, which corresponds to specific anatomical structures (e.g., lumbar spinal column), receives enhanced scanning with multiple passes to achieve higher artifact reduction quality. Other regions receive standard single-pass scanning, optimizing the overall measurement time while maintaining high quality where most needed.
2Measurement precision
If gradient fields are increased to improve spatial coding accuracy, then signal coding precision improves, but the system becomes more sensitive to edge region artifacts
Solution Approach 1:
The patent employs asymmetric scanning patterns where the second region is scanned multiple times with different phase-encoding directions. This asymmetric approach allows the system to average out gradient field variations and edge region artifacts that would be problematic with symmetric scanning, thereby maintaining spatial coding accuracy while reducing sensitivity to edge artifacts.
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 effectively reduces artifacts from edge regions and maintains efficient data acquisition, as the measurement time increase is minimized, allowing for high-resolution images in shorter periods.
Implementation Method 1
the examination subject in a tunnel opening of a magnetic resonance apparatus is positioned in a strong, static, homogeneous basic magnetic field (also called a B0 field) with a field strength of 0.2 to 7 Tesla or more, such that nuclear spins in the subject orient along the basic magnetic field
Implementation Method 2
Radio-frequency (RF) excitation pulses and possible refocusing pulses are radiated into the examination subject to trigger magnetic resonance signals
Implementation Method 3
Rapidly switched (activated) magnetic gradient fields are superimposed on the basic magnetic field for spatial coding of the magnetic resonance data (measurement data)
Data Source
AI summary
In a method and magnetic resonance system for the acquisition of magnetic resonance data in a selected region of an examination subject, magnetic resonance data are acquired more than once using a magnetic resonance system, magnetic resonance data are acquired more than once from a selected partial region the portion of k-space filled with data corresponding to the selected region of the subject, and the multiply acquired magnetic resonance data are processed into a data set, the aforementioned partial region is selected so as to be located decentrally in k-space, meaning that it is asymmetrical relative to the center of k-space.