This study aims to provide reliable patient monitoring inside the MRI, and improve cardiac MRI imaging of arrhythmia patients. ECGs within the MRI are overlaid with a Magneto-Hydro-Dynamics (MHD) voltage (VMHD), so S-T segment elevation during ischemia cannot be determined. In addition, cardiac MRI of arrhythmia patients is blurred due to non-robust synchronization to the R-wave. We will develop an MR-safe 12-lead Electro-Cardio-Gram (ECG) system, permitting ECG acquisition during cardiac MR imaging. We will extract the real ECG signals (ECGreal) from the MHD-contaminated ECGs, allowing for reliable patient monitoring. The extracted clean ECGreal will be sent to the MRI for selective cardiac gating based on PVC/Sinus Rhythm (SR) beats. The separated MHD signals (VMHD) will be used for a non- invasive estimation of systolic beat-to-beat cardiac stroke volume (SV.
Aim #1 : MR compatible 12-lead ECG acquisition system We will develop an MR compatible ECG acquisition system in which the recorded 12-lead ECG signals are not distorted or masked by induced MR gradient and Radio Frequency (RF) pulses in 3 Tesla MRI scanners. Reduction of noise during MRI-gradient rise/fall will be removed via a novel electronic switching-circuit that cuts off ECG transmission to the ECG amplifier during gradient ramps and also during RF-pulse transmission. The system will also meet the FDA patient heating limits during MRI imaging.
Aim #2 : Real-time ECG processing for MHD signal filtering We will develop a real-time adaptive filtering procedure to extract ECGreal and VMHD from 12-lead ECGs. This software will provide diagnostic quality ECGs and deliver a non-invasive estimation of SV, computed from the systolic-integrated VMHD. We will develop a real-time PVC/SR beat classification method based on a novel 3-D representation of 12-lead ECG data. Scan triggering and image data can then be utilized according to the current beat type present, for use in triggering cardiac MRI. To test the system functionality, acute arrhythmia will be created in a swine model.
Aim # 3: Improved Cardiac MRI imaging in Arrhythmia patients We will evaluate the hardware and software developed in Aims 2 and 3 in a cohort of 10 Idiopathic Outflow Tract (IOT) PVC patients. Conventional ECG-gated scans will be performed, comparing the new platform to the commercial 4-lead ECG systems used today. Image spatial resolution and acquisition times will be compared. In severe (>20% PVC/SR beats) IOT PVC patients, selective imaging during PVCs will be attempted, possibly providing unique insight on heart motion during PVCs.

Public Health Relevance

This project addresses the difficulty to obtain artifact-free Electro-cardiogram (ECGs) traces in high-field MRI. High- fidelity 12-lead ECGs are required for patient physiological monitoring, and can improve MRI-scan synchronization. Major artifacts are MRI gradient ramps [1], and Magneto-Hydro-Dynamic (MHD) voltages, which masks acute-ischemia monitoring [2]. We will develop a clinical 12-lead ECG [3-6] that operates safely at 3T, and use it in arrhythmia patients.

National Institute of Health (NIH)
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Small Research Grants (R03)
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Medical Imaging Study Section (MEDI)
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Krosnick, Steven
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Brigham and Women's Hospital
United States
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Schmidt, Ehud J; Halperin, Henry R (2018) MRI use for atrial tissue characterization in arrhythmias and for EP procedure guidance. Int J Cardiovasc Imaging 34:81-95
Zhang, Shelley HuaLei; Tse, Zion Tsz Ho; Dumoulin, Charles L et al. (2016) Gradient-induced voltages on 12-lead ECGs during high duty-cycle MRI sequences and a method for their removal considering linear and concomitant gradient terms. Magn Reson Med 75:2204-16
Schmidt, Ehud J; Watkins, Ronald D; Zviman, Menekhem M et al. (2016) A Magnetic Resonance Imaging-Conditional External Cardiac Defibrillator for Resuscitation Within the Magnetic Resonance Imaging Scanner Bore. Circ Cardiovasc Imaging 9:
Gregory, T Stan; Oshinski, John; Schmidt, Ehud J et al. (2015) Continuous Rapid Quantification of Stroke Volume Using Magnetohydrodynamic Voltages in 3T Magnetic Resonance Imaging. Circ Cardiovasc Imaging 8:
Oster, Julien; Llinares, Raul; Payne, Stephen et al. (2015) Comparison of three artificial models of the magnetohydrodynamic effect on the electrocardiogram. Comput Methods Biomech Biomed Engin 18:1400-17
Schmidt, Ehud J (2015) Magnetic Resonance Imaging-Guided Cardiac Interventions. Magn Reson Imaging Clin N Am 23:563-77
Gregory, T Stan; Schmidt, Ehud J; Zhang, Shelley Hualei et al. (2014) 3DQRS: a method to obtain reliable QRS complex detection within high field MRI using 12-lead electrocardiogram traces. Magn Reson Med 71:1374-80
Gregory, T Stan; Schmidt, Ehud J; Zhang, Shelley Hualei et al. (2014) Left-ventricular mechanical activation and aortic-arch orientation recovered from magneto-hydrodynamic voltages observed in 12-lead ECGs obtained inside MRIs: a feasibility study. Ann Biomed Eng 42:2480-9
Tse, Zion Tsz Ho; Dumoulin, Charles L; Clifford, Gari D et al. (2014) A 1.5T MRI-conditional 12-lead electrocardiogram for MRI and intra-MR intervention. Magn Reson Med 71:1336-47
Schmidt, Ehud J; Tse, Zion T H; Reichlin, Tobias R et al. (2014) Voltage-based device tracking in a 1.5 Tesla MRI during imaging: initial validation in swine models. Magn Reson Med 71:1197-209