Active Noise Suppression in MRI Receivers

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Solution Overview

Problem

Magnetic resonance tomography scanners require costly shielding cabins to suppress both emissions and interferences, which increases operational costs and does not effectively minimize interference signals at the receive antenna.

Innovation Solution

A noise suppressor system with sensors and a noise suppression controller that captures interference signals, determines a noise suppression signal, and emits it via controllable radio frequency amplifiers and transmit antennas to cancel out interference at the receive antenna, optimizing amplification, phase shift, and frequency response based on signal propagation geometry.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If costly shielding cabins are installed around the magnetic resonance scanner, then emissions and interferences are reduced, but operational costs increase and interference signals at the receive antenna are not effectively minimized

Engineering Contradiction:

Improveinterference signals at receive antennaVSAvoidshielding cabin structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The harmful interference signals are extracted and identified separately from the useful magnetic resonance signals using sensors positioned to detect only the interference components. This allows the interference to be suppressed independently without requiring comprehensive shielding of the entire scanner environment.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The detected interference signals are converted into beneficial noise suppression signals through phase inversion and amplification. The same interference that harms the reception is transformed into a corrective signal that actively cancels the interference at the receive antenna, turning a harmful factor into a useful tool for suppression.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Object-generated harmful factors

If shielding cabins are installed to reduce emissions, then emission limits are complied with, but operational costs increase

Engineering Contradiction:

Improveradio frequency emissionsVSAvoidoperational costs

Core Design Contradiction:

Object-generated harmful factorsVSLoss of energy

Solution Approach 1:

The system performs self-regulation of emissions by detecting interference signals and generating compensating signals that reduce the overall emission footprint. The scanner actively manages its own electromagnetic environment through feedback control, eliminating the need for external shielding infrastructure and associated operational costs.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If local coils are used to improve signal-to-noise ratio, then reception sensitivity is improved, but susceptibility to interference signals increases

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidinterference signal susceptibility

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

Additional sensors are introduced as intermediary elements that detect interference signals before they reach the receive antenna. These sensors act as mediators that capture the interference component separately, allowing it to be suppressed through signal processing without affecting the useful magnetic resonance signals received by the local coils.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system implements a feedback mechanism where detected interference signals are processed and fed back as noise suppression signals that are combined with the received signals. This closed-loop control continuously adjusts the suppression signals to match the actual interference conditions, maintaining optimal signal-to-noise ratio while counteracting interference.

Inventive Principle:

Principle #23Feedback

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

Reduces interference signals at the receive antenna without significantly affecting the magnetic resonance signal, thereby minimizing the need for costly shielding and improving signal-to-noise ratio, while reducing radiation into the environment.

Implementation Method 1

the noise suppression controller is configured to determine a noise suppression signal such that an effect of the interference signal is reduced at the receive antenna

Methodology Applied

Scientific EffectDestructive interference: Interference

Implementation Method 2

The controllable radio frequency amplifier is configured to amplify an input signal as a function of settings, in particular an amplification, a phase shift, and/or a frequency response

Methodology Applied

Scientific EffectSignal amplification: Magnetic Amplifier

Data Source

PatentUS11709215B2Device and method for active local suppression of reception in magnetic resonance recordings

Publication Date: 2023.07.25 SIEMENS HEALTHINEERS AG

AI summary

A magnetic resonance tomography scanner with a noise suppressor for suppressing interferences of reception and a method for operation of the magnetic resonance tomography scanner are provided. The noise suppressor receives an interference signal with a sensor, determines a noise suppression signal with a noise suppression controller, and sends the noise suppression signal using a controllable radio frequency amplifier via a transmit antenna, so that the interference signal on a receive antenna of the magnetic resonance tomography scanner is reduced.