Phase-Corrected Multi-Coil MRI Reconstruction
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Solution Overview
Problem
Conventional magnetic resonance imaging systems using multiple coils face challenges in preserving phase information, particularly with low signal-to-noise ratios, and often result in phase singularities and artifacts like 'dark point artifacts' due to phase offsets from receiver circuit errors.
Innovation Solution
A method is developed to determine and correct coil-specific base phases for each pixel in magnetic resonance images, using pre-measurements and autocorrelation or correlation functions to associate region-specific base phases with each coil, thereby correcting phase information and preventing phase singularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If phase-dependent image generation methods (LC or ACC) are used to preserve phase information, then phase information is preserved, but phase singularities occur under specific circumstances
Solution Approach 1:
The patent applies preliminary action by determining coil-specific base phases through pre-measurements before the actual image acquisition. These base phases are stored and used to correct phase information in subsequent imaging, preventing phase singularities from occurring during the main measurement process.
Solution Approach 2:
The patent implements feedback by using the determined base phases to correct coil-specific pixel phases during image reconstruction. The corrected phase information is then used to generate the final phase-dependent image, creating a closed-loop system that eliminates phase singularities.
2Measurement precision
If multiple coils are used to acquire MR data sets, then image quality improves, but phase offsets from receiver circuit errors cause phase singularities
Solution Approach 1:
The patent extracts the harmful phase offsets from the coil signals by determining coil-specific base phases through pre-measurements. These base phases represent the phase offsets introduced by receiver circuits, and they are separated from the actual signal phase information to enable independent correction.
Solution Approach 2:
The patent introduces base phases as an intermediary element that mediates between the raw coil signals and the final phase-dependent image. These base phases serve as correction factors that compensate for receiver circuit errors without affecting the underlying phase information of the examined object.
3Measurement precision
If sum of squares technique is used for coil combination, then good magnitude images are achieved with high signal-to-noise ratio, but phase information is lost
Solution Approach 1:
The patent segments the coil combination process into separate magnitude and phase handling. Magnitude information from multiple coils is combined using the sum of squares technique to achieve high signal-to-noise ratio, while phase information is preserved through separate correction using base phases, allowing both magnitude quality and phase preservation to coexist.
Data Source
AI summary
In a method and magnetic resonance system to determine a magnetic resonance (MR) image of an examination subject, wherein multiple coil-specific MR data sets that are acquired by multiple coils are used for the MR image. Each pixel of the MR image is determined from at least two coil-specific MR data sets of different coils (6-10), and each pixel has a pixel magnitude and a pixel phase. Multiple coil-specific base phases are determined that are respectively associated with one of the multiple coils. For each pixel multiple coil-specific pixel, magnitudes and multiple pixel phases are determined. A coil-specific pixel magnitude and a coil-specific pixel phase are respectively determined from a coil-specific MR data set of one of the multiple coils (7-10). The coil-specific pixel phases with the corresponding, coil-specific base phase, and the multiple coil-specific pixel magnitudes and the multiple coil-specific pixel phases are combined into the pixel magnitude and the pixel phase of the pixel.