Magnetic Resonance Spectroscopic Image Phase Correction
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Solution Overview
Problem
Magnetic resonance spectroscopic imaging (MRSI) faces challenges in achieving high accuracy and short processing time due to low signal-to-noise ratio (SNR) and spatial non-uniformity in phase distribution when using multi-array coils (MAC), which affects phase correction accuracy and increases computational load.
Innovation Solution
A method involving pixel-by-pixel phase correction using non-water-suppressed image signals with high SNR, followed by MAC summation and phase correction in the spectrum-axis direction, with weighting coefficients calculated from SNR values to improve SNR and reduce processing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If water-suppressed measurement is performed to obtain metabolite signals, then metabolite signal extraction is enabled, but signal-to-noise ratio becomes low
Solution Approach 1:
The patent applies preliminary phase correction using non-water-suppressed measurement data before performing water-suppressed measurement and MAC summation. This preliminary action establishes accurate phase reference information that guides subsequent processing, enabling metabolite signal extraction while maintaining high signal-to-noise ratio through optimized coil combination.
2Manufacturing precision
If phase correction is performed on low SNR spectrum signals, then spectral phase alignment is achieved, but phase correction accuracy is reduced
Solution Approach 1:
The patent introduces non-water-suppressed measurement data as an intermediary with high signal-to-noise ratio to determine phase correction parameters. This intermediary provides reliable phase information that is then applied to correct the water-suppressed measurement data, enabling accurate phase alignment without directly processing low SNR signals.
Solution Approach 2:
Phase correction parameters are calculated in advance using high SNR non-water-suppressed data before processing the water-suppressed measurement data. This preliminary calculation of phase parameters ensures accurate phase correction is applied to the metabolite signals, overcoming the low SNR condition.
3Productivity
If MAC summation is performed without phase correction to reduce computation time, then processing speed is improved, but spatial non-uniformity degrades image quality
Solution Approach 1:
The patent performs preliminary phase correction on individual coil images before MAC summation using phase parameters derived from non-water-suppressed data. This preliminary phase alignment ensures that when coils are summed, spatial non-uniformity is minimized while maintaining processing efficiency, as the correction is based on pre-calculated parameters rather than iterative optimization.
4Reliability
If conventional MAC summation methods are used, then coil signals are combined, but spatial non-uniformity in phase distribution reduces accuracy
Solution Approach 1:
The patent applies local phase correction to each coil's signal using spatially-varying phase parameters determined from non-water-suppressed measurement data. This local quality adjustment ensures that each coil's contribution to the MAC summation is phase-aligned at each spatial location, eliminating spatial non-uniformity while maintaining effective signal combination.
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 enables high-accuracy, rapid generation of magnetic resonance spectroscopic images with MAC summation, even with spatial non-uniformity, by leveraging high SNR data for phase correction and optimizing computational efficiency.
Implementation Method 1
irradiates a radiofrequency magnetic field at specific frequency to a subject placed in a static magnetic field, so as to excite nuclear magnetization of each nucleus of hydrogen
Implementation Method 2
excite nuclear magnetization of each nucleus of hydrogen or the like contained in the subject and to detect a magnetic resonance signal generated from the subject
Data Source
AI summary
An object of the invention is to obtain a magnetic resonance spectroscopic image to which the MAC summation is applied with high accuracy and in short time, even though a phase characteristic distribution of the MAC has a spatial non-uniformity, in the MRSI measurement using a magnetic resonance imaging apparatus provided with a MAC. Using a non-water-suppressed image signal with high SNR, obtained in the non-water-suppressed measurement (a reference measurement) without water suppression, a correction value for correcting the phase distortion for the MAC summation is calculated on each pixel in each coil. After correcting a phase on each pixel in each coil of a main-scan image signal measured under suppressing water (water-suppressed image signal) using the corrective value, signal adding operation (summation) is performed. Then, a phase correction in a spectrum-axis is to be performed on the summed spectrum signal.