title: Left-ventricular mechanical activation and aortic-arch orientation recovered from magneto-hydrodynamic voltages observed in 12-lead ECGs obtained inside MRIs: a feasibility study.
abstract: To explore use of the Magnetohydrodynamic Voltage (VMHD), observed in intra-MRI 12-lead electrocardiograms (ECG), to indicate the timing of the onset of left-ventricular mechanical activation (LVMA) and the orientation of the aortic-arch (AAO). Blood flow through the aortic arch during systole, in the presence of the MRI magnetic field (B 0), generates VMHD. Since the magnitude and direction of VMHD are determined by the timing and directionality of blood flow relative to B 0, we hypothesized that clinically useful measures, LVMA and AAO, could be extracted from temporal and vectorial VMHD characteristics. VMHD signals were extracted from 12-lead ECG traces by comparing traces obtained inside and outside the MRI scanner. VMHD was converted into the Vectorcardiogram frame of reference. LVMA was quantified in 1 subject at 1.5T and 3 subjects at 3T, and the result compared to CINE MRI. AAO was inferred for 4 subjects at 3T and compared to anatomical imaging of the aortic arch orientation in the transverse plane. A < 10% error was observed in LVMA measurements, while a < 3° error was observed in aortic arch orientation measurements. The temporal and vectorial nature of VMHD is useful in estimating these clinically relevant parameters.
authors.affiliation: College of Engineering, The University of Georgia, 597 D.W. Brooks Drive, Athens, GA, 30602, USA.
authors.forename: T Stan
authors.initials: TS
authors.lastname: Gregory
authors.forename: Ehud J
authors.initials: EJ
authors.lastname: Schmidt
authors.forename: Shelley Hualei
authors.initials: SH
authors.lastname: Zhang
authors.forename: Raymond Y
authors.initials: RY
authors.lastname: Kwong
authors.forename: William G
authors.initials: WG
authors.lastname: Stevenson
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Murrow
authors.forename: Zion Tsz Ho
authors.initials: ZT
authors.lastname: Tse
mesh_terms: D001013:Aorta, Thoracic / Q000502:physiology*; D004562:Electrocardiography; D005240:Feasibility Studies; D006352:Heart Ventricles; D006801:Humans; D060328:Magnetic Phenomena; D008279:Magnetic Resonance Imaging; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D016276:Ventricular Function