ECG Electrode Placements for Magnetohydrodynamic Voltage Suppression and improving Cardiac Gating in high-field MRI
KeywordsCardiac Magnetic Resonance Electrode Placement Cardiac Gating Cardiac Electrical Activity Severe Motion Artefact
The accuracy of Electrocardiogram (ECG) gating for synchronization of MR scanner image acquisition and cardiac electrical activity is of great importance for acquiring high-quality Cardiac Magnetic Resonance (CMR) images free of motion artefacts. The distortion of ECG traces by Magnetohydrodynamic Voltages (VMHD) induced by interaction between the MRI static magnetic field (B0) and rapid left-ventricular blood ejection during systole can lead to false and/or intermittent QRS complex detection and images with severe motion artefacts . We hypothesized that an optimized electrode placement for the reduction of induced VMHD could be derived based on a thoracic model to increase the accuracy of QRS complex detection.
A 43.41% reduction in VMHD during the S-T segment (Figure 1f) was observed in ECGs using the MHD-suppressed placement relative to the conventional placement, while preserving the QRS complex (Figure 1e), resulting in an average increase in the Se and +P rate of 14.22% and 15.48%, respectively (Figure 1e-g). Rpeak amplitude inside the MRI in the MHD-suppressed placement had <5% deviation from the standard placement outside of the MRI (Figure 1e). As compared to the conventional electrode placement (Figure 1c-d), MHD suppression may result from decreased visibility of the aorta through the lungs at the MHD-suppressed placement.
Electrode placement recommendations were computed and validated in a 3T MRI, illustrating an increased accuracy in QRS complex detection using the MHD-suppressed placement.
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