MR Signal Correction via Iterative Phase Amplitude Modulation
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Solution Overview
Problem
Current magnetic resonance (MR) examination methods face challenges in achieving high-quality MR signals due to the presence of a transmission signal component in the reception signal, which is difficult to suppress, limiting the quality of measurement data and preventing simultaneous transmission and reception of MR signals.
Innovation Solution
A method that generates a correction signal matching the transmission signal, modulated by phase and amplitude, is used to iteratively correct the response signal, effectively suppressing the transmission signal component through a signal combiner, potentially achieving up to 100 dB suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a transmitted signal is radiated into the test object and a response signal is recorded simultaneously, then measurement time is reduced and acquisition efficiency is improved, but the received signal contains a transmitted signal component that impairs its quality
Solution Approach 1:
The invention uses the transmitted signal itself as the correction signal, converting the harmful transmitted signal component into a beneficial reference for cancellation. By using the same signal source that causes interference as the basis for correction, the system transforms the problem of signal contamination into an opportunity for precise subtraction, achieving over 100 dB suppression of the transmitted signal component.
Solution Approach 2:
The invention dynamically adjusts parameters including phase and amplitude of the correction signal to match the transmitted signal characteristics. By continuously optimizing these parameters during the measurement process, the system adapts to changing conditions and maintains effective cancellation of the transmitted signal component while preserving the response signal quality.
2Measurement precision
If complete decoupling of transmitting and receiving coils is implemented, then transmitted signal component in received signal is reduced, but device complexity increases
Solution Approach 1:
The invention introduces a correction signal as an intermediary element that mediates between the transmitted and received signals. This correction signal acts as a reference that enables mathematical cancellation of the transmitted signal component without requiring physical separation or complex decoupling structures between coils, thereby simplifying the hardware design while maintaining signal quality.
Solution Approach 2:
The invention replaces complex mechanical or geometric decoupling mechanisms with a signal processing approach. Instead of using intricate coil arrangements or physical barriers to prevent interference, the system uses digital signal correction and subtraction methods to eliminate the transmitted signal component, transitioning from a hardware-based solution to a software-based solution.
3Measurement precision
If geometric decoupling and digital signal cancellation are applied, then transmitted signal component is reduced by about 70 dB, but further reduction to 100 dB is unattainable with current methods
Solution Approach 1:
The invention implements a feedback mechanism where the transmitted signal serves as a reference that is continuously compared with the received signal. The system uses this feedback information to dynamically adjust and optimize the correction signal, enabling iterative refinement of the cancellation process and achieving suppression levels exceeding 100 dB that were previously unattainable.
Solution Approach 2:
The invention performs preliminary characterization of the transmitted signal before it contaminates the response signal measurement. By establishing a reference model of the transmitted signal in advance and using it to pre-correct the received signal, the system eliminates the need for complex post-processing and achieves superior cancellation performance with reduced computational complexity.
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 enables high-quality MR examination by significantly reducing the transmission signal component, allowing for high-quality measurement data and enabling new applications such as unpulsed sequences, increased acquisition efficiency, and measurement of MR signals with ultra-short T2 times.
Implementation Method 1
a transmit signal, typically defining an RF signal, is irradiated into the test object and a response signal, which is emitted by the test object in reaction to the transmit signal
Implementation Method 2
To generate magnetization within a test object, the test object can be placed in a primary magnetic field
Data Source
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AI summary
A method for magnetic resonance imaging of a test object is described, wherein a measurement sequence is used in which the magnetic resonance response to the transmitted signal is measured during transmission. It is proposed to generate a correction signal corresponding to the transmitted signal and to use it to correct the response signal. For this purpose, the correction signal is modulated by a phase value and an amplitude value. The phase value and the amplitude value are automatically and iteratively adjusted using an optimization procedure based on the current state value of the measurement signal to optimally correct the response signal. Furthermore, a high-frequency unit (1) is described with which the method according to the invention can be carried out.