Detailing the use of magnetohydrodynamic effects for synchronization of MRI with the cardiac cycle: A feasibility study

Abstract

Purpose: To investigate the feasibility of using magnetohydrodynamic (MHD) effects for synchronization of magnetic resonance imaging (MRI) with the cardiac cycle. Materials and Methods:The MHD effect was scrutinized using a pulsatile flow phantom at B 0 ¼ 7.0 T. MHD effects were examined in vivo in healthy volunteers (n ¼ 10) for B 0 ranging from 0.05-7.0 T. Noncontrast-enhanced MR angiography (MRA) of the carotids was performed using a gated steadystate free-precession (SSFP) imaging technique in conjunction with electrocardiogram (ECG) and MHD synchronization. Results:The MHD potential correlates with flow velocities derived from phase contrast MRI. MHD voltages depend on the orientation between B 0 and the flow of a conductive fluid. An increase in the interelectrode spacing along the flow increases the MHD potential. In vivo measurement of the MHD effect provides peak voltages of 1.5 mV for surface areas close to the common carotid artery at B 0 ¼ 7.0 T. Synchronization of MRI with the cardiac cycle using MHD triggering is feasible. MHD triggered MRA of the carotids at 3.0 T showed an overall image quality and richness of anatomic detail, which is comparable to ECG-triggered MRAs. Conclusion:This feasibility study demonstrates the use of MHD effects for synchronization of MR acquisitions with the cardiac cycle.

Finite element analysis of magnetohydrodynamic effects on blood flow in an aneurysmal geometry

“…6 In this direction, there have been substantial efforts in removing the noise from the signal by proper filtering. [7][8][9] The nature of the problem however remains and might get more intense while moving gradually from the MRI to the time-dependent PC-MRI which can provide a picture of the hemodynamics. In this direction, tube or rotating phantoms were developed to test if PC-MRI introduces visualization errors determining the accuracy degree of the technique.…”

Left-Ventricular Mechanical Activation and Aortic-Arch Orientation Recovered from Magneto-Hydrodynamic Voltages Observed in 12-Lead ECGs Obtained Inside MRIs: A Feasibility Study

“…Due to the potential for variability in the MHD signal in healthy patients (34), an averaged MHD-based orientation measure was obtained for each 20-second breath hold. A similar method could then be applied to deduce the aortic orientation in the sagittal and coronal planes by altering Eqn.…”

The Magnetohydrodynamic Effect and Its Associated Material Designs for Biomedical Applications: A State‐of‐the‐Art Review

“…To increase the ability to perform cardiac synchronization during MRI imaging, customized gating and synchronization algorithms have been developed to identify the timing of ventricular contraction as marked by the QRS complex of the ECG [83, 84] . Early correlation to blood flow, and therefore cardiac activity, has led to the development of VMHD driven MRI synchronization algorithms, based on the cyclic rhythm of the true QRS complex generated from the sinoatrial node and induced MHD from aortic blood flow, which allow for fine-tuning of image acquisition to better capture flow [83–86] .…”