12-lead ECG in a 1.5 Tesla MRI: Separation of real ECG and MHD voltages with adaptive filtering for gating and non-invasive cardiac output
© Tse et al; licensee BioMed Central Ltd. 2010
Published: 21 January 2010
The Magneto-Hydro-Dynamic (MHD) effect arises when conductive blood flows in the MRI magnetic field (B0). MHD generates a voltage which distorts the real electrocardiogram (ECGreal), especially during the S-T segment where flow from the left ventricle (LV) into the aorta contributes to a large MHD voltage . A dominant QRS and undistorted S-T segment are important for MRI gating and physiological monitoring for ischemia during cardiac imaging/interventions .
We hypothesized that adaptive filtering could separate between MHD and ECGreal, and that the MHD signal could non-invasively estimate cardiac output.
The filtering procedure separates the ECGreal and MHD signals in 12-lead ECGs acquired within the MRI. The QRS complex becomes dominant, as required for good MRI gating, while preserving S-T segment fidelity for physiological monitoring during imaging/interventions. MHD signals allow for non-invasive monitoring of beat-to-beat cardiac output.