MRI Homodyne Filter Phase Correction Asymmetric K-Space

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Solution Overview

Problem

Conventional asymmetric Fourier imaging (AFI) methods for magnetic resonance imaging (MRI) often result in artifacts due to phase errors, particularly when estimating phase distributions, leading to reduced accuracy in image reconstruction from asymmetrically sampled k-space data, while increasing data processing time.

Innovation Solution

A magnetic resonance imaging apparatus and method that includes phase correction and filter processing to generate image data from asymmetrically sampled k-space data, utilizing a homodyne filter with adjustable gain and phase distribution estimation across the entire frequency range to minimize phase correction errors and optimize data processing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If phase correction is performed using conventional AFI methods on asymmetrically sampled k-space data, then image reconstruction is achieved, but phase errors cause artifacts and reduced accuracy

Engineering Contradiction:

Improveimage accuracyVSAvoidphase errors and artifacts

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a homodyne filter as an intermediary component between the asymmetrically sampled k-space data and the phase correction process. This filter processes the k-space data before phase correction, enabling more accurate phase estimation and reducing artifacts caused by conventional direct phase correction methods

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies preliminary filtering and phase estimation actions before the main phase correction step. By pre-processing the k-space data with a homodyne filter and estimating phase distribution in advance, the method prepares the data in a state that minimizes phase errors during subsequent reconstruction

Inventive Principle:

Principle #10Preliminary action

2Productivity

If conventional AFI methods are used for phase correction, then processing is faster, but image accuracy is reduced due to phase errors

Engineering Contradiction:

Improvedata processing speedVSAvoidimage accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent changes key processing parameters by introducing a homodyne filter with adjustable characteristics and modifying the phase correction approach to work with asymmetrically sampled data. These parameter changes enable accurate phase correction while maintaining processing efficiency suitable for clinical applications

Inventive Principle:

Principle #35Parameter changes

3Loss of time

If asymmetric sampling is used in k-space, then data acquisition time is reduced, but phase correction errors increase leading to artifacts

Engineering Contradiction:

Improvedata acquisition timeVSAvoidphase correction errors and artifacts

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The homodyne filter serves as an intermediary that bridges the gap between asymmetric sampling and accurate phase correction. It processes the asymmetrically sampled data to create a foundation that enables accurate phase estimation without requiring symmetric sampling, thus reducing acquisition time while minimizing artifacts

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies local quality enhancement by using a homodyne filter that selectively processes different regions of k-space data with appropriate weighting. This localized processing approach maintains accuracy in critical regions while tolerating asymmetry in other regions, reducing overall phase errors

Inventive Principle:

Principle #3Local quality

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

The solution enhances image accuracy equivalent to symmetrically sampled data while minimizing the increase in data processing time, reducing phase correction errors and artifacts, and improving image quality.

Implementation Method 1

MRI is an imaging method which excites nuclear spin of an object set in a static magnetic field with a RF (radio frequency) signal having the Larmor frequency magnetically and reconstruct an image based on NMR (nuclear magnetic resonance) signals generated due to the excitation

Methodology Applied

Scientific EffectLarmor frequency:

Implementation Method 2

reconstruct an image based on NMR (nuclear magnetic resonance) signals generated due to the excitation

Methodology Applied

Scientific EffectNuclear magnetic resonance:

Implementation Method 3

In the Margosian method, a homodyne filter as a window function is applied to asymmetrically sampled k-space data

Methodology Applied

Scientific EffectHomodyne detection: Homodyne Detection

Data Source

PatentUS8648599B2Magnetic resonance imaging apparatus and magnetic resonance imaging method

Publication Date: 2014.02.11 TOSHIBA MEDICAL SYST CORP

AI summary

According to one embodiment, a magnetic resonance imaging apparatus includes an imaging unit and data processing condition setting unit. The imaging unit is configured to acquire magnetic resonance data corresponding to a sampling region asymmetric in a wave number direction in k-space from an object to generate image data based on the magnetic resonance data by data processing including phase correction and filter processing for obtaining a complex conjugate. The data processing condition setting unit is configured to set a condition for the data processing according to an imaging condition influencing a phase distribution used for the phase correction or the phase distribution.