K-space trajectory correction for MR imaging artifacts
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Solution Overview
Problem
Current RESOLVE sequence measurements in magnetic resonance systems suffer from ringing artifacts due to discrepancies in gradient moments, requiring complex and time-consuming calibration measurements to adjust echo spacing and gradient orientations, which are not flexible and cannot compensate for system changes or subject-specific fluctuations.
Innovation Solution
A method that corrects k-space trajectories using frequency-dependent parameters characterizing the gradient unit, such as gradient impulse response functions, to adjust the planned k-space trajectory, thereby avoiding artifacts with minimal computational overhead and allowing for flexible correction across different frequency components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If complex calibration measurements are performed to adjust echo spacing and gradient orientations, then artifact reduction is achieved, but measurement time and system complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating correction values for k-space trajectories based on expected gradient deviations before actual measurement. This allows the system to compensate for gradient moment discrepancies without performing time-consuming calibration measurements during the imaging process, thus reducing artifact while saving time.
Solution Approach 2:
The patent creates a corrected model of the k-space trajectory that copies and adjusts the original trajectory parameters. By calculating corrected gradient moments and using these to define adjusted k-space trajectories, the system generates artifact-free images without requiring physical calibration measurements, effectively replacing complex measurement procedures with computational corrections.
2Object-affected harmful factors
If fixed calibration procedures are used to correct gradient moments, then artifact reduction is achieved, but flexibility to accommodate system changes and subject-specific variations is lost
Solution Approach 1:
The patent implements dynamics by making the k-space trajectory correction adaptive rather than fixed. The system calculates corrected gradient moments that can be adjusted based on actual measurement conditions and applies these dynamically during the imaging process. This allows the correction parameters to adapt to system changes and subject-specific variations while maintaining artifact reduction.
Solution Approach 2:
The patent applies parameter changes by modifying the k-space trajectory parameters (gradient moments, echo spacing) based on calculated correction values. The system changes the trajectory parameters dynamically to compensate for gradient deviations, allowing flexible adaptation to different imaging conditions, coil configurations, and subject variations while maintaining image quality.
3Manufacturing precision
If precise gradient moment matching is performed to avoid artifacts, then image quality improves, but computational complexity and processing time increase
Solution Approach 1:
The patent extracts the correction calculation from complex iterative optimization procedures and implements it as a direct computational approach. By calculating the difference between desired and actual gradient moments and applying straightforward corrections to the k-space trajectory parameters, the system achieves precise trajectory matching with reduced computational complexity.
Solution Approach 2:
The patent replaces complex mechanical calibration procedures with computational corrections. Instead of physically adjusting gradient hardware to achieve precise moment matching, the system uses mathematical calculations to determine corrected gradient moments and applies these computationally, substituting mechanical adjustment complexity with simpler computational processing.
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 simplifies the correction of k-space trajectories, reducing computational burden and enabling flexible artifact avoidance in RESOLVE measurements, improving image quality without the need for extensive calibration, and accommodating system and subject-specific variations.
Implementation Method 1
Rapidly switched magnetic gradient fields, called gradients for short, are superimposed on the basic magnetic field for the purpose of spatially encoding the measurement data
Implementation Method 2
radiofrequency excitation pulses (RF pulses) are radiated into the examination subject, the triggered nuclear spin resonances are measured as signals
Implementation Method 3
the examination subject is positioned for this purpose in a magnetic resonance device in a comparatively strong, static, homogeneous basic magnetic field, also referred to as the B0 field
Data Source
AI summary
In a method for acquiring measurement data using a magnetic resonance (MR) system having a gradient unit, frequency-dependent parameters characterizing the gradient unit of the MR system are accessed (e.g. loaded from a memory), a k-space trajectory of a RESOLVE (Readout Segmentation Of Long Variable Echo trains) sequence planned for a MR measurement is accessed, MR measurement data is acquired based on the planned k-space trajectory and reconstructing image data from the MR measurement data, and an electronic signal is provided that represents the reconstructed image data as an output of the MR system. The k-space trajectory may have a frequency component in at least one direction. The planned k-space trajectory may be corrected based on at least one frequency component of the planned k-space trajectory and the frequency-dependent parameters.