Dipole location using SQUID based measurements: Application to magnetocardiography

We report a method of inferring the dipole location using iterative nonlinear least square optimization based on Levenberg–Marquardt algorithm, wherein, we use different sets of pseudo-random numbers as initial parameter values. The method has been applied to (i) the simulated data representing the calculated magnetic field distribution produced by a point dipole placed at a known position, (ii) the experimental data from SQUID based measurements of the magnetic field distribution produced by a source coil carrying current, and (iii) the actual experimentally measured magnetocardiograms of human subjects using a SQUID based system.

► Magnetocardiography (MCG) measurements were done using SQUID based system.
► Equivalent current dipole model (ECD) was adopted for the cardiac source.
► Inverse problem done using iterative nonlinear least square optimization.
► A set of pseudo random numbers was assumed as initial values for optimization.
► No prior knowledge about the physiological activities of the source required.