Single and Distributed Dipole Models Analysis of Cardiac Source Activation using MCG Signals

  In biomagnetic inverse problems different models of the source activation can be used depending on the physiology of the problem. In this study we compared different source models to perform current source reconstruction in MCG. We first considered a single dipole source model using a non linear minimization algorithm to localize the source of the heart activity in different segments of the MCG signals. We then repeated the same analyses using a distributed sources model and calculated an equivalent dipole located in the center of mass of all dipoles to compare it with the results of the single dipole model localization. The differences in the positions and orientations were evaluated under different conditions, for normal subjects at rest and after stress exercise test, using normal component and vector component data. Different configurations of the volume conductor model were used, to evaluate the influence of the geometry and of the conductivity inhomogeneities on the inverse solution. The results show that 3D data allow finding smaller differences between the single dipole and the equivalent dipole localized solutions.