ECG Signal Processing Apparatus for MRI Noise Suppression
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Solution Overview
Problem
Conventional adaptive filters fail to adequately remove noise from ECG signals acquired during MRI procedures, leading to instability in detecting the R-wave due to magnetic fields and RF pulses, often removing cardiac action potentials excessively.
Innovation Solution
An ECG signal processing apparatus that uses an adaptive filter with noise estimation and removal functions, employing gradient magnetic field signals to estimate and subtract noise from ECG signals, particularly during imaging periods, while storing reference parameters from non-imaging periods to maintain cardiac action potential integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional adaptive filter is used to remove noise from ECG signals during MRI imaging, then noise removal capability is improved, but cardiac action potential is excessively removed and detection stability deteriorates
Solution Approach 1:
The patent segments the ECG signal processing into distinct phases: acquiring signals during non-imaging periods for reference parameter storage, and processing signals during imaging periods using stored reference parameters. This temporal segmentation allows the system to differentiate between noise characteristics and cardiac action potential characteristics, enabling selective noise removal without excessive distortion of cardiac signals.
Solution Approach 2:
The patent performs preliminary action by acquiring ECG signals and storing reference parameters during non-imaging periods before the actual imaging begins. These reference parameters characterize the normal cardiac action potential and are used during imaging periods to guide noise removal, ensuring that cardiac signals are preserved while noise is eliminated.
2Measurement precision
If noise estimation from gradient magnetic field control signal is improved, then noise removal effectiveness is improved, but false removal of cardiac action potential increases
Solution Approach 1:
The patent applies local quality by using different reference parameters for different temporal segments of the ECG signal. Reference parameters stored during non-imaging periods (when noise is minimal) are selectively applied during imaging periods, allowing precise noise estimation and removal only where needed, while preserving cardiac action potential information in other segments.
Solution Approach 2:
The patent implements feedback by continuously comparing current ECG signal characteristics with stored reference parameters during imaging periods. This feedback mechanism allows the system to adjust noise removal operations in real-time, removing noise that matches the reference noise pattern while preserving cardiac action potential patterns that differ from the reference noise characteristics.
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
Effectively suppresses noise caused by MRI procedures, allowing stable detection and extraction of cardiac action potentials, ensuring reliable synchronization signals for MRI imaging.
Implementation Method 1
Magnetic flux density around an electrocardiograph and its electrodes temporally changes, which generates induced electromotive force, and the induced electromotive force is mixed into an ECG signal as noise
Data Source
AI summary
In one embodiment, an ECG signal processing apparatus is configured to be connected with an electrocardiograph and an MRI apparatus and includes memory circuitry and processing circuitry configured to (a) store a parameter of an ECG signal as a first parameter in the memory circuitry, the ECG signal being acquired from the electrocardiograph operating in combination with the MRI apparatus in a period during which a gradient pulse is not applied by the MRI apparatus, (b) implement an adaptive filter for estimating noise mixed into the ECG signal due to the gradient pulse, by using the first parameter stored in the memory circuitry and a gradient magnetic field signal acquired from the MRI apparatus in a period during which the gradient pulse is applied, and (c) remove the noise mixed into the ECG signal in the period during which the gradient pulse is applied, by using estimated noise.