MR Image Reconstruction With Asymmetric k-Space Phase Correction
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Solution Overview
Problem
Existing image reconstruction methods from asymmetrically scanned k-space data in magnetic resonance tomography suffer from blurring and ringing artifacts, particularly when the partial Fourier factor is close to 50%, and do not produce sharp images with minimal artifacts.
Innovation Solution
A method and apparatus that utilize an iterative k-space reconstruction combined with an image reconstruction method, employing a phase image and asymmetrical weighting filters to reconstruct images from asymmetrically acquired k-space data, addressing both symmetrical and asymmetrical parts of the data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If Homodyne/Margosian reconstruction is used for asymmetrically scanned k-space data, then acquisition time is reduced, but image quality deteriorates with blurring artifacts
Solution Approach 1:
The patent applies preliminary phase correction by reconstructing a low-resolution phase image from the central symmetric k-space data before the main image reconstruction. This preliminary phase information is then used to correct the phase in the final image reconstruction, preventing blurring artifacts while maintaining the benefits of partial Fourier acquisition
Solution Approach 2:
The patent modifies the reconstruction parameters by using asymmetric weighting filters that adaptively weight different regions of the k-space data. The weighting scheme changes based on the partial Fourier factor and the specific acquisition pattern, optimizing the balance between using available data and minimizing artifacts
2Manufacturing precision
If POCS iterative method is used for asymmetrically scanned k-space data, then image reconstruction is achieved, but ringing artifacts increase
Solution Approach 1:
The patent introduces an intermediary phase correction step that acts as a mediator between the raw asymmetric k-space data and the final image reconstruction. By using the low-resolution phase image as an intermediary, the method avoids the direct artifacts generated by POCS while still achieving accurate image reconstruction
Solution Approach 2:
The patent performs preliminary phase correction before the main reconstruction process, which prevents the formation of ringing artifacts rather than attempting to remove them afterward. This preliminary action modifies the data in a way that avoids the harmful artifacts in the first place
3Duration of action of moving object
If partial Fourier acquisition is used to shorten echo train length, then capture time is reduced, but blurring artifacts strengthen
Solution Approach 1:
The patent dynamically adjusts reconstruction parameters based on the partial Fourier factor. When the partial Fourier factor is close to 50%, the method applies stronger phase correction and uses asymmetric weighting that compensates for the reduced data, maintaining image sharpness despite the shortened echo train
Solution Approach 2:
The patent employs asymmetric weighting filters that are specifically designed for asymmetric k-space sampling. The weighting scheme is asymmetric in the same way the data acquisition is asymmetric, which properly balances the contribution of different k-space regions and prevents blurring that would occur with symmetric weighting
Data Source
AI summary
A method for reconstructing MR tomography images from asymmetrically acquired k-space raw data, with symmetrical and asymmetrical parts, may include reconstructing a phase image from the symmetrical k-space data, applying an iterative k-space reconstruction starting with a base image, and forming a working space via k-space transform. A weighting filter may be applied, assigning zero weight where no raw data exists, lower weight to symmetrical data, and non-zero weight to other data. A complex intermediate image is generated by image space transform of weighted k-space data, phase-corrected with the phase image, and the final result image is obtained as the real part of the phase-corrected intermediate image.