Cardiac and Respiratory MRI Gating Using Combined Wavelet Sub-Band Decomposition and Adaptive Filtering

Abi-Abdallah, D.; Drochon, Agnès; Robin, Vincent; Fokapu, Odette

doi:10.1007/s10439-007-9285-y

Cited by 19 publications

(17 citation statements)

References 14 publications

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“…In this study we examine the MHD effect on several ECG signals recorded on different subjects while exposed to a 1.5 Tesla static magnet and assess the major alterations imposed on the signal. We also review a previously elaborated real time R peak detection algorithm [1] and test its capacity of extracting correct triggers from these MHD contaminated signals.…”

Section: Alterations In Human Ecg Due To the Magnetohydrodynamic Effementioning

confidence: 99%

Alterations in human ECG due to the MagnetoHydroDynamic effect: A method for accurate R peak detection in the presence of high MHD artifacts

Abi-Abdallah

Robin

Drochon

et al. 2007

2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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Blood flow in high static magnetic fields induces elevated voltages that contaminate the ECG signal which is recorded simultaneously during MRI scans for synchronization purposes. This is known as the magnetohydrodynamic (MHD) effect, it increases the amplitude of the T wave, thus hindering correct R peak detection. In this paper, we inspect the MHD induced alterations of human ECG signals recorded in a 1.5 Tesla steady magnetic field and establish a primary characterization of the induced changes using time and frequency domain analysis. We also reexamine our previously developed real time algorithm for MRI cardiac gating and determine that, with a minor modification, this algorithm is capable of achieving perfect detection even in the presence of strong MHD artifacts.

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Section: Alterations In Human Ecg Due To the Magnetohydrodynamic Effementioning

confidence: 99%

Alterations in human ECG due to the MagnetoHydroDynamic effect: A method for accurate R peak detection in the presence of high MHD artifacts

Abi-Abdallah

Robin

Drochon

et al. 2007

2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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“…Thus, many techniques have been developed to reduce the effects of these signals. For example, gradient artifacts can be reduced with algorithms based on adaptive filter techniques [33], Bayesian filters [34], and independent component analysis [35]. For a more thorough evaluation of the improvement in QRS detection provided by the presented method to reduce V MHD , the ECG recordings may need to be preprocessed to reduce the effects of gradient artifacts.…”

Section: Discussionmentioning

confidence: 99%

ECG Electrode Placements for Magnetohydrodynamic Voltage Suppression

2018

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This study aims to investigate a set of electrocardiogram (ECG) electrode lead locations to improve the quality of four-lead ECG signals acquired during magnetic resonance imaging (MRI). This was achieved by identifying electrode placements that minimized the amount of induced magnetohydrodynamic voltages (V MHD ) in the ECG signals. Reducing V MHD can improve the accuracy of QRS complex detection in ECG as well as heartbeat synchronization between MRI and ECG during the acquisition of cardiac cine. A vector model based on thoracic geometry was developed to predict induced V MHD and to optimize four-lead ECG electrode placement for the purposes of improved MRI gating. Four human subjects were recruited for vector model establishment (Group 1), and five human subjects were recruited for validation of V MHD reduction in the proposed four-lead ECG (Group 2). The vector model was established using 12-lead ECG data recorded from Group 1 of four healthy subjects at 3 Tesla, and a gradient descent optimization routine was utilized to predict optimal four-lead ECG placement based on V MHD vector alignment. The optimized four-lead ECG was then validated in Group 2 of five healthy subjects by comparing the standard and proposed lead placements. A 43.41% reduction in V MHD was observed in ECGs using the proposed electrode placement, and the QRS complex was preserved. A V MHD -minimized electrode placement for four-lead ECG gating was presented and shown to reduce induced magnetohydrodynamic (MHD) signals, potentially allowing for improved cardiac MRI physiological monitoring.

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“…An alternative to the LTI framework is the adaptive filter, which can be designed to have minimal delay. One type of adaptive filter is the recursive least squares filter, which can be used to filter ECG signal but requires knowledge of desired output (31). Another type of adaptive filter is the Kalman filter, which models the signal as a linear dynamical system and optimally estimates the current state of the system from both the previous time step estimate as well as the current incomplete noisy measurement.…”

Section: Discussionmentioning

confidence: 99%

Kalman filtering for real‐time navigator processing

Spincemaille

Nguyen

Prince

et al. 2008

Magnetic Resonance in Med

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Navigator echoes are used in high-resolution cardiac MRI for tracking physiological motion to suppress motion artifacts. Alternatives to the conventional diaphragm navigator such as the cardiac fat navigator and the k-space center signal (self-navigator) were developed to monitor heart motion directly. These navigator data can be noisy or may contain undesirable frequency components. Real-time filtering of navigator data without delay, as opposed to the previously used retrospective frequency band filtering , is required for effective prospective navigator gating. One of the commonly used real-time filtering techniques is the Kalman filter, which adaptively estimates motion and suppresses measurement noise by using Bayesian statistics and a motion model. The Kalman filter is investigated in this work to filter noise and distinguish cardiac and respiratory components in navigator data. Preliminary imaging data demonstrate the feasibility of real-time Kalman filtering for prospective respiratory self-gating in CINE cardiac MRI. Magn Reson Med 60:158-168, 2008. An important approach to suppressing motion artifacts in MRI is the navigator method (1), which measures physiological motion directly from MR signal (navigator) and synchronizes image data acquisition with the physiological motion. For example, the diaphragm navigator, which images a column of tissue through the right diaphragm (2), has been successfully used for respiratory motion artifact suppression in high-resolution coronary MRA (3-5). Navigators that more directly measure cardiac motion have been developed in recent years for cardiac MRI. The cardiac fat navigator (6) tracks the motion of the heart by using a spatial-spectral excitation of the epicardial fat. The concept of self-gating based on the motion induced variation of the k-space center signal has been introduced as a "wireless" alternative to ECG gating (7,8) and has, more recently, been performed for respiratory gating using either a small subset of imaging projections (9) or an additional sampling of the center of k-space within each TR (10,11). These new navigators may have more complex signal behavior than the diaphragm navigator, which tracks a sharp diaphragm edge. For the newer navigators, additional processing may be required to filter out noise and separate cardiac and respiratory components for cardiac MRI applications. For k-space-center based self-gating, the k-space center signal has a complex dependence on the slice position, orientation, thickness, and field-of-view, and on local and global physiological motion within the excited imaging volume. Filtering of this k-space center signal is required to extract the right motion parameter for motion gating. Most current cardiac MRI methods that use cardiac and/or respiratory self-gating are retrospective techniques that require multiple acquisitions followed by a sorting of the entire over-scanned dataset offline. Self-gating signals are processed using frequency filters, which are inherently slow and unsuitable for real-time proces...

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Cardiac and Respiratory MRI Gating Using Combined Wavelet Sub-Band Decomposition and Adaptive Filtering

Cited by 19 publications

References 14 publications

Alterations in human ECG due to the MagnetoHydroDynamic effect: A method for accurate R peak detection in the presence of high MHD artifacts

Alterations in human ECG due to the MagnetoHydroDynamic effect: A method for accurate R peak detection in the presence of high MHD artifacts

ECG Electrode Placements for Magnetohydrodynamic Voltage Suppression

Kalman filtering for real‐time navigator processing

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