INITIAL ESTIMATION METHODS FOR DIPOLE MODELING IN LOCALIZATION OF EPILEPTOGENIC FOCUS

Although great sensitivities to initial estimates is an inherent featu re of iterative dipole optimization algorithms, the study of better in itial estimates has been neglected. For convergence to a correct solut ion, the initial estimates should be extremely close to the desired so lution and be attributed to only a single dipole focus. To alleviate t he interference of background and multiple foci, the singular value de composition (SVD) technique is used initially to extract the dominant component of the EEG spike for dipole localization. By observing the t hree-dimensional topographic mapping, the initial estimates of the dip ole parameter set can be computed from the intersection between the nu ll potential plane and from the peak and valley potentials. This work also compares initial estimations of simulation data, including noisy data, noisy data with SVD process and noise-free data. Experimental re sults confirm that good initial estimates for the dipole parameters ar e necessary to ensure rapid convergence to the correct solution. (C) 1 998 IPEM. Published by Elsevier Science Ltd. All rights reserved.