In vitro study to simulate the intracardiac magnetohydrodynamic effect

15.09.2014

Buchenberg WB, Mader W, Hoppe G, Lorenz R, Menza M, Büchert M, Timmer J, Jung B.

Magn Reson Med. 2015;74(3):850-7.

Magn Reson Med.        online article

Blood flow causes induced voltages via the magnetohydrodynamic (MHD) effect distorting electrograms (EGMs) made during magnetic resonance imaging (MRI). In order to investigate the MHD effect in this context, this work simulates MHD voltages occurring inside the human heart in an in-vitro model system inside a 1.5T MR system. A common electrophysiological (EP) system and standard EP catheter were used to acquire bipolar EGMs. These signals were characterized with respect to high pass filter settings of the EP pre-amplifier. A new approach to eliminate MHD distortions from intracardiac EGMs is proposed based on the analytical calculation of the MHD signal from flow-sensitive MR phase contrast data. The MHD signal vanished almost entirely at a cut-off frequency ? 40Hz of the high pass filter as commonly used in bipolar EGMs. A significant MHD signal remained at low cut-off frequencies (0.05Hz or 0.2Hz) as expected. MHD signals reconstructed from the MR flow data were in excellent agreement with the MHD signal measured by the EP system. Applying high cut-off frequencies of the high pass filter suppress the acquisition of MHD signals. Phase contrast MRI can be used to reconstruct MHD signals and apply those to correct EGMs.