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Restauration et analyse de l'électrocardiogramme acquis pendant les examens d'imagerie par résonance magnétique :

Abstract : The electrocardiogram (ECG) is used in magnetic resonance imaging (MRI) for patient monitoring and for synchronization of the MR images. The environment of MRI (magnetic field, magnetic field gradients and radiofrequency waves) complicates the acquisition of the ECG and needs specific developments. In the first part, the thesis analyses the interferences of the MRI on the ECG and vice versa. This part concludes with a physical model of the interferences between MRI and ECG. Thanks to this model an ECG sensor that is better adapted to the MRI environment has been constructed. In the second part, artefact suppression superposing the ECG signal by software is discussed. A mathematical model is proposed as base for the artefact suppression. The linear and time invariant model (LTI) of the gradient artefact generation is verified and validated. The test methods for the verification of restoration algorithms of the ECG are defined. For offline restoration, the method by FFT, by cross-power spectrum, Wiener filtering and least squares are studied. In the third part, a second category of algorithms is tested in case of online restoration. The LMS and RLS filters and their subtypes are analysed. In the summary, the Wiener filter is used for easier manual annotation of artefacted ECG. The LMS filter as well as a QRS detection and beat classification module are applied to a annotated ECG database in order to show the real-time suppression efficiency of the artefacts due to magnetic field gradient artefacts
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https://hal.univ-lorraine.fr/tel-01752521
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Roger Abächerli. Restauration et analyse de l'électrocardiogramme acquis pendant les examens d'imagerie par résonance magnétique :. Autre. Institut National Polytechnique de Lorraine, 2005. Français. ⟨NNT : 2005INPL114N⟩. ⟨tel-01752521⟩

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