MRI Water-Fat Separation via Phase Correction Decimation
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Solution Overview
Problem
The existing MRI techniques, such as the TRW-S algorithm, often erroneously estimate the effect of static magnetic field non-uniformity, leading to 'swap' events where water and fat components are incorrectly identified in images, causing errors in image generation.
Innovation Solution
An advanced MRI apparatus and image processing method that performs decimation processing on phase correction data to generate lower-resolution phase correction data, based on component ratios and MR signals, to accurately estimate the true phase and reduce errors in water and fat image separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the TRW-S algorithm is used to estimate the effect of static magnetic field non-uniformity, then the estimation accuracy is improved, but swap events between water and fat regions still occur causing image errors
Solution Approach 1:
The patent divides the image processing into multiple stages: first generating initial water and fat images using the TRW-S algorithm, then performing swap detection by comparing signal intensities, and finally correcting identified swap regions. This segmentation of the processing workflow allows the system to leverage the TRW-S algorithm's estimation accuracy while adding a safety mechanism to prevent reliability issues from swap events.
Solution Approach 2:
The patent implements a feedback mechanism where the system detects swap events by comparing signal intensities in corresponding regions of water and fat images, then uses this detection information to correct the images. The feedback loop continuously monitors and adjusts the images to eliminate swap errors, thereby maintaining both the estimation accuracy benefit and the reliability requirement.
2Measurement precision
If high-resolution phase correction data is used, then the precision of magnetic field non-uniformity estimation is improved, but processing time and computational complexity increase
Solution Approach 1:
The patent applies decimation processing to reduce the resolution of phase correction data to a level that is sufficient for accurate swap detection and correction, rather than processing the full high-resolution data. This partial action approach maintains the precision needed for the critical swap detection function while significantly reducing the overall processing time and computational burden.
Solution Approach 2:
The patent segments the processing by applying decimation only to the phase correction data used for swap detection, while preserving full resolution for the final image output. This selective resolution reduction allows the system to minimize processing time for the computational-intensive swap detection step without compromising the quality of the final medical images.
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 effectively suppresses swap events between water and fat regions, enabling more accurate estimation and separation of water and fat components in MRI images, thereby improving image quality.
Implementation Method 1
An MRI apparatus is an imaging apparatus which magnetically excites nuclear spin of an object placed in a static magnetic field with a radio frequency (RF) having the Larmor frequency and reconstructs an image based on the magnetic resonance (MR) signals emitted from the object due to the excitation
Implementation Method 2
The phase of each pixel value of the first image and the second image is affected by non-uniformity of a static magnetic field
Data Source
AI summary
In one embodiment, an MRI apparatus includes: a scanner for acquiring MR signals from an imaging region in which substances having different magnetic resonance frequencies are included; and processing circuitry. The processing circuitry is configured to: calculate phase correction data, which includes information on phase rotation amount due to non-uniformity of a static magnetic field, from MR signals; generate an image by using the phase correction data and the MR signals such that a signal from at least one of the substances in the imaging region is suppressed in the image; and perform decimation processing on first phase correction data to generate second phase correction data, based on information related to a component ratio of the plurality of substances in the imaging region and a plurality of MR signals, wherein resolution of the second phase correction data is lower than the first phase correction data.