Exploring magnetohydrodynamic voltage distributions in the human body: Preliminary results

Background The aim of this study was to noninvasively measure regional contributions of vasculature in the human body using magnetohydrodynamic voltages (V _MHD ) obtained from electrocardiogram (ECG) recordings performed inside MRI’s static magnetic field (B ₀ ). Integrating the regional V _MHD over the S _wave -T _wave segment of the cardiac cycle (V _segment ) provides a noninvasive method for measuring regional blood volumes, which can be rapidly obtained during MRI without incurring additional cost. Methods V _MHD was extracted from 12-lead ECG traces acquired during gradual introduction into a 3T MRI. Regional contributions were computed utilizing weights based on B ₀ ’s strength at specified distances from isocenter. V _segment mapping was performed in six subjects and validated against MR angiograms (MRA). Results Fluctuations in V _segment , which presented as positive trace deflections, were found to be associated with aortic-arch flow in the thoracic cavity, the main branches of the abdominal aorta, and the bifurcation of the common iliac artery. The largest fluctuation corresponded to the location where the aortic arch was approximately orthogonal to B ₀ . The smallest fluctuations corresponded to areas of vasculature that were parallel to B ₀ . Significant correlations (specifically, Spearman’s ranked correlation coefficients of 0.96 and 0.97 for abdominal and thoracic cavities, respectively) were found between the MRA and V _segment maps (p < 0.001). Conclusions A novel non-invasive method to extract regional blood volumes from ECGs was developed and shown to be a rapid means to quantify peripheral and abdominal blood volumes.