MRI Phase Correction Using Pixel-Wise Reference Subtraction
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Solution Overview
Problem
Current MRI methods face challenges in accurately combining phase images from multiple receiver coils due to phase offsets, often requiring additional volume coils or coarse estimations, which can introduce noise and reduce image quality, especially at high magnetic field strengths.
Innovation Solution
A method that acquires a reference image and a target image with phase values, subtracts the reference phase values from the target phase values pixel-by-pixel to correct for phase offsets, and combines these images using specific mathematical operations to produce offset-compensated phase and magnitude images, eliminating the need for additional volume coils and enhancing signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional volume coils or body coils are used for phase referencing, then phase offset correction can be achieved, but device complexity increases and acquisition time increases
Solution Approach 1:
Each receiver coil performs its own phase referencing by using itself as the reference for other coils. The method eliminates the need for separate body coils or volume reference coils by having each coil contribute to the phase correction of the entire coil array through mutual referencing.
Solution Approach 2:
Receiver coils serve dual functions: they act as both the reference coil and the measured coil in the phase correction process. This multi-functionality eliminates the need for dedicated reference coils, reducing device complexity while maintaining correction accuracy.
2Measurement precision
If additional volume coils or body coils are used for phase referencing, then phase offset correction can be achieved, but acquisition time increases
Solution Approach 1:
The phase referencing process is merged with the standard multi-coil imaging acquisition. All coils acquire data simultaneously during the same excitation cycle, and phase correction is performed through computational processing rather than requiring separate reference scans, thereby eliminating additional acquisition time.
Solution Approach 2:
The system performs phase correction using data already acquired during normal imaging operations, without requiring separate reference scans or additional acquisition time. Each coil's data is used to correct phase offsets in real-time through post-processing.
3Reliability
If phase values are used from multiple receiver coils, then signal-to-noise ratio can be improved, but phase offset errors accumulate and reduce image quality
Solution Approach 1:
The method implements a feedback mechanism where phase offset information derived from one coil is used to correct phase values in other coils. This iterative correction process continuously refines phase accuracy across the entire coil array, ensuring that phase values remain precise even when combining data from multiple coils for improved signal-to-noise ratio.
Solution Approach 2:
A computational phase correction algorithm acts as an intermediary between raw phase data from multiple coils and the final combined image. This intermediary process calculates and applies phase offset corrections systematically, preventing error accumulation while preserving the signal-to-noise ratio benefits of multi-coil data 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 method provides accurate, phase-offset-compensated images that can be easily combined, improving the signal-to-noise ratio and reducing acquisition time, while maintaining contrast and detail in MRI images, especially at high magnetic field strengths.
Implementation Method 1
Excited by an electro-magnetic radio-frequency pulse from a transmitter coil the nuclei resonating at this frequency deflect and then gradually relax towards the static field while emitting detectable electro-magnetic radiation, which can be captured as an 'echo' at a certain time after excitation (the 'echo time') by a receiver coil
Implementation Method 2
For aligning the magnetic spin of the nuclei, mostly of protons in water molecules in the body tissue, the patient is placed inside a powerful static magnetic field
Implementation Method 3
the nuclei resonating at this frequency deflect and then gradually relax towards the static field while emitting detectable electro-magnetic radiation
Data Source
Figure 1~3
Figure 2
Figure 4a~4d
AI summary
The present invention relates to a method for Magnetic Resonance Imaging to depict an object by an image (SK,p) having pixels representing volume element of the object, comprising: immobilising the object and acquiring (4) a reference image (SR,p) at a first echo time (TER) immediately following an excitation (6), wherein said reference image (SR,p) is complex-valued, with a reference magnitude value (mR,p) and a reference phase value (ϑR,p) for each pixel; acquiring (7) a target image (ST,p) of the object with said receiver coil at a pre-selected second echo time (TET), wherein said target image (ST,p) is complex-valued, with a target magnitude value (mT,p) and a target phase value (ϑT,p) for each pixel; subtracting (10), pixel by pixel, the reference phase value (ϑR,p) from the target phase value (ϑT,p) to obtain (10) a corrected phase value (ϑK,p) for each pixel; and obtaining said image (SK,p) from said target magnitude values (mT,p) and said corrected phase values (ϑK,p).