Virtual Coil Array Phase Calibration for MRI Nyquist Artifacts
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Solution Overview
Problem
Magnetic Resonance Imaging (MRI) systems face challenges in achieving high image quality due to phase errors in odd and even echo data, leading to Nyquist artifacts in the final MRI images, caused by imperfections in the hardware and readout gradient directions.
Innovation Solution
The method involves obtaining and processing odd and even echo data sets from a receiving coil array using parallel magnetic resonance imaging techniques like SENSE and GRAPPA, determining phase information, and constructing a virtual coil array to perform parallel reconstruction, thereby calibrating phase differences and reducing artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If parallel magnetic resonance imaging is performed separately on odd and even echo data sets, then phase information can be accurately determined, but the processing complexity increases
Solution Approach 1:
The patent divides the imaging data into separate odd echo and even echo data sets, and performs parallel magnetic resonance imaging processing independently on each data set. This segmentation allows for accurate determination of phase information for each echo type while managing processing complexity through systematic separation of the processing steps.
2Reliability
If a virtual coil array with increased number of coil channels is constructed, then image quality and signal-to-noise ratio improve, but the computational burden increases
Solution Approach 1:
The patent constructs a virtual coil array by mapping odd and even echo data sets to virtual coil channels, effectively creating additional coil elements without physical hardware. This copying approach increases the effective number of coil channels to improve image quality and signal-to-noise ratio while managing computational resources through virtual rather than physical expansion.
3Manufacturing precision
If phase calibration is performed using separate odd and even echo processing, then Nyquist artifacts are reduced, but the reconstruction time increases
Solution Approach 1:
The patent performs parallel magnetic resonance imaging processing on odd and even echo data sets in advance to determine their respective phase information before final image reconstruction. This preliminary action enables accurate phase calibration that reduces Nyquist artifacts, while the structured approach allows for efficient implementation that manages reconstruction time.
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 improves the signal-to-noise ratio and reduces artifacts in the final MRI images, enhancing image quality by effectively handling phase errors and increasing the effective number of coil channels, thus decreasing the geometric factor and improving image clarity.
Implementation Method 1
hydrogen protons in a human body are excited by a radio-frequency excitation based on a magnetic resonance phenomenon
Implementation Method 2
a magnetic resonance signal with position information is received by using a receiving coil
Data Source
AI summary
Methods, devices, systems and apparatus for magnetic resonance imaging are provided. In an example, a method includes: obtaining M imaging data sets collected by a receiving coil array including N coil channels under M radio-frequency excitations, determining odd echo phase information and even echo phase information for each of the imaging data sets, mapping M odd echo data sets and M even echo data sets of the imaging data sets as a virtual imaging data set for a virtual coil array that includes N×M×2 virtual coil channels, and performing parallel magnetic resonance imaging based on the odd echo phase information and the even echo phase information of each of the imaging data sets, the virtual imaging data set and parallel reconstruction reference data.