Magnetic Resonance Imaging Compensation Gradient for Interference
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Solution Overview
Problem
Magnetic interference fields caused by objects with different magnetic susceptibility than surrounding tissue can disrupt magnetic resonance imaging, leading to signal loss and artifacts in the vicinity of these objects.
Innovation Solution
A magnetic resonance imaging method that involves a sequence with multiple repetition intervals and the activation of a magnetic compensation gradient opposed to the interference field, ensuring correct refocusing of nuclear spins and reducing artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic resonance imaging is performed in the vicinity of an interference object with different magnetic susceptibility, then imaging capability is maintained, but magnetic interference fields cause signal loss and image artifacts
Solution Approach 1:
The patent applies preliminary anti-action by calculating the magnetic susceptibility of the interference object before imaging and pre-defining compensation gradients that oppose the expected magnetic interference field. These compensation gradients are integrated into the imaging sequence in advance, creating a counteracting magnetic field that prevents signal loss and artifacts before they occur during actual imaging.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the magnetic field parameters through compensation gradients. The system modifies the gradient strength and direction parameters in real-time based on the calculated magnetic susceptibility of the interference object, transforming the imaging conditions to compensate for the interference and maintain reliable imaging capability.
2Manufacturing precision
If a magnetic compensation gradient is activated to oppose the magnetic interference field, then image artifacts are reduced, but the imaging sequence complexity increases
Solution Approach 1:
The patent applies preliminary action by performing a preliminary calculation of the interference object's magnetic susceptibility before the actual imaging sequence. Based on this preliminary information, the compensation gradients are pre-configured and integrated into the imaging sequence, allowing the system to reduce artifacts without requiring complex real-time adjustments during imaging.
Solution Approach 2:
The patent introduces an intermediary calculation step that determines the magnetic susceptibility of the interference object. This intermediary information serves as a bridge between the interference object and the imaging sequence, allowing the system to generate appropriate compensation gradients without directly increasing the complexity of the core imaging sequence itself.
3Reliability
If refocusing of nuclear spins is performed at the end of each repetition interval, then signal coherence is maintained, but the imaging sequence duration increases
Solution Approach 1:
The patent implements periodic action by refocusing nuclear spins at the end of each repetition interval in a rhythmic, periodic manner. This periodic refocusing maintains signal coherence throughout the imaging sequence while optimizing the timing to minimize the overall sequence duration, balancing coherence maintenance with time efficiency.
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 allows for effective magnetic resonance imaging near interference objects by compensating the interference field, resulting in artifact-reduced image data and accurate representation of tissue in the vicinity of the object.
Implementation Method 1
An interference object may be present in an examination region of a magnetic resonance recording. This interference object is characterized by having a magnetic susceptibility that differs from the magnetic susceptibility of tissue surrounding the interference object. This interference object therefore can lead to magnetic interference fields
Implementation Method 2
magnetic resonance raw data are acquired from the examination region by execution of a magnetic resonance sequence having multiple repetition intervals with refocusing of nuclear spins in the examination region at the end of each repetition interval
Implementation Method 3
Radio-frequency pulses, in particular excitation pulses, are then emitted by a radio-frequency antenna unit via suitable antennas, and this leads to the nuclear spins (spins) of specific atoms excited in a resonant manner by these radio-frequency pulses being tilted by a defined flip angle with respect to the magnetic field lines of the basic magnetic field
Data Source
AI summary
To enable improved magnetic resonance imaging in the vicinity of an interference object that produces a magnetic interference field in an examination region, in a method and apparatus for magnetic resonance imaging of the examination region magnetic resonance raw data are acquired from the examination region by execution of a magnetic resonance sequence having multiple repetition intervals and refocusing of spins in the examination region at the end of each repetition interval repetition intervals. During at least part of the duration of the acquisition of the magnetic resonance raw data, a magnetic compensation gradient is activated that is opposed to the magnetic interference field.