Independent component analysis-based artefact reduction: application to the electrocardiogram for improved magnetic resonance imaging triggering

Abstract

Electrocardiogram (ECG) is required during magnetic resonance (MR) examination for monitoring patients under anaesthesia or with heart diseases and for synchronizing image acquisition with heart activity (triggering). Accurate and fast QRS detection is therefore desirable, but this task is complicated by artefacts related to the complex MR environment (high magnetic field, radio-frequency pulses and fast switching magnetic gradients). Specific signal processing has been proposed, whether using specific MR QRS detectors or ECG denoising methods. Most state-of-the-art techniques use a connection to the MR system for achieving their task, which is a major drawback since access to the MR system is often restricted. This paper introduces a new method for on-line ECG signal enhancement, called ICARE, which takes advantage of using multi-lead ECG and does not require any connection to the MR system. It is based on independent component analysis (ICA) and applied in real time. This algorithm yields accurate QRS detection for efficient triggering.

ECG-based gating in ultra high field cardiovascular magnetic resonance using an independent component analysis approach

“…A similar ICA-based method was utilized previously for the suppression of gradient artefacts from 3-lead ECG signals acquired during MRI [21]. These gradient induced artefacts exhibit temporal variations due to different MRI sequences, slice locations and orientations.…”

“…The resulting IC ${\hat{s}}_{\text{k,ECG}}$ is a linear combination of the original ECG leads. Based on these linear combinations, the gradient artefacts in ${\hat{s}}_{\text{k,ECG}}$ will still respect the linear time invariant assumption needed for the application of previously published methods for suppressing the gradient artefacts [21,34,35]. …”

“…In ECG signal processing, ICA was used for many applications such as the extraction of the foetal ECG, for artefact removal or for the extraction of atrial activity [18-20]. In CMR, ICA was used to reduce the gradient artefacts from 3-lead ECG signals [21]. In this work, ICA is applied to 12-lead ECG signals recorded inside a 7 T MR scanner.…”

Capteur ECG intelligent pour la synchronisation des séquences en IRM et le monitorage des patients

“…Comme l'information des gradients de champ magnétique de l'IRM n'est pas toujours accessible, nous avons mis au point une méthode basée sur la séparation des sources ECG-artéfacts (ICA) [18] (méthode Icare). Une détection QRS par ondelette (méthode Drone) [19] (Fig.…”

Left-Ventricular Mechanical Activation and Aortic-Arch Orientation Recovered from Magneto-Hydrodynamic Voltages Observed in 12-Lead ECGs Obtained Inside MRIs: A Feasibility Study

“…Traditional methods for cardiac MRI gating treat the MHD signal as an artifact and attempt to remove it from the real ECG (5,6). Methods of QRS complex detection in the presence of high-field MRI include Vectorcardiogram-based (VCG) approaches (7,8), signal pre-processing (9), independent component analysis (10,11), and cross-correlation based methods (12). …”