MRI Parallel Imaging with Outer Volume Suppression
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Solution Overview
Problem
Magnetic resonance imaging techniques, such as parallel imaging and zoomed methods, suffer from convolution artifacts and noise amplification due to inherent errors in reconstruction and imperfect saturation or excitation, limiting their application, especially in high acceleration factors and specific imaging methods like fMRI and spine imaging.
Innovation Solution
Combining a zoomed technique with parallel imaging to reduce or suppress artifacts caused by reconstruction errors and imperfect saturation or excitation, allowing for improved image quality and higher acceleration factors by using small local coils and multi-channel transmission methods for local excitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If parallel imaging is used to accelerate data acquisition, then the time required for obtaining image data is reduced, but convolution artifacts arise in the image
Solution Approach 1:
The patent applies preliminary action by using outer volume suppression (OVS) saturation pulses emitted in advance before the actual data acquisition. These saturation pulses preemptively suppress signals from outer regions that would otherwise cause convolution artifacts, allowing parallel imaging to proceed with higher acceleration factors while maintaining image quality.
Solution Approach 2:
The patent implements preliminary anti-action by introducing saturation pulses that counteract the harmful effect of convolution artifacts before they can occur during data acquisition. The saturation pulses create a preemptive suppression of unwanted signals, effectively neutralizing the artifact formation mechanism in advance.
2Productivity
If high acceleration factors are used in parallel imaging, then data acquisition is further accelerated, but image disruptions and artifacts increase
Solution Approach 1:
The patent uses preliminary saturation pulses to prepare the spin state before high-speed data acquisition. By suppressing outer region signals in advance, the system enables higher acceleration factors without the usual image disruptions, maintaining reliability even at elevated imaging speeds.
Solution Approach 2:
The saturation pulses act as an intermediary mechanism between the acceleration requirement and image quality requirement. They mediate the conflict by suppressing the harmful interactions between accelerated data acquisition and artifact formation, allowing high productivity to coexist with high reliability.
3Productivity
If zoomed method is used to reduce field of view, then data acquisition is accelerated, but convolution artifacts occur due to imperfect saturation or excitation
Solution Approach 1:
The patent applies preliminary saturation pulses before the zoomed data acquisition to suppress signals from outer regions. This preemptive action ensures that when the reduced FOV data is acquired at high speed, convolution artifacts are minimized because the outer region signals have already been suppressed.
Solution Approach 2:
The patent applies local quality by using location-specific saturation pulses tailored to different regions. The saturation pulses are applied selectively to outer regions while preserving the desired signal in the central region of interest, creating different signal characteristics in different spatial locations to optimize both acceleration and artifact suppression.
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
Significantly reduces image artifacts and enables the use of higher acceleration factors, improving image quality and making parallel imaging more viable for applications previously restricted by artifact issues.
Implementation Method 1
magnetic resonance imaging technique... use of multiple data acquisition (RF) coils, that each acquire, either simultaneously or substantially simultaneously, a set of magnetic resonance data
Implementation Method 2
The respective data sets acquired by the multiple coils are combined in an appropriate manner using information about the individual coils, such as their location or sensitivity
Implementation Method 3
either the signals from the outer regions are suppressed with saturation pulses emitted in advance (known as the 'outer volume suppression' or 'OVS' method)
Implementation Method 4
A gradient coil system (3) is composed of a number of windings... for generation of linear gradient field in the respective directions of the Cartesian coordinate system
Implementation Method 5
A basic field magnet (1) generates a temporally-constant strong magnetic field for polarization or alignment of the nuclear spins... A radio-frequency antenna (4) converts the radio-frequency pulses emitted by a radio-frequency power amplifier into an alternating magnetic field
Data Source
AI summary
In a magnetic resonance imaging method and apparatus, magnetic resonance data are acquired (an examination subject) using a zoomed method, and reconstruction of the image of the examination subject is undertaken using a parallel imaging reconstruction method.