Magnetocardiographic functional localization using a current dipole in a realistic torso

Abstract

We describe a fast and numerically effective biomagnetic inverse solution using a moving dipole in a realistic homogeneous torso. We applied the localization model and high-resolution magnetocardiographic mapping to localize noninvasively the ventricular preexcitation site in ten patients suffering from Wolff-Parkinson-White syndrome. In all cases, the computed localization results were compared to the results obtained by invasive catheter technique. Using a standard-size torso model in all cases, the average 3-D distance between the computed noninvasive locations and the invasively obtained results was 2.8 +/- 1.4 cm. When the torso was rescaled to better match the true shape of the subject in five cases, the 3-D average was improved to 2.2 +/- 1.0 cm. This accuracy is very satisfactory, suggesting that the method would be clinically useful.

EEG and MEG: forward solutions for inverse methods

“…Boundary element methods (BEM's) for solving (5) have been widely studied in the MEG and EEG literature (cf. [4], [9], [10], [15], [16], [26], [27], [30]- [32], [35]- [37], [39], [40], [43], [46], [47], and [50]). Here, we review the BEM approach to solving the E/MEG forward problem using the method of weighted residuals as a framework.…”

“…To reduce the BEM equations to the inner product of a kernel and the dipole moment, each element in the vector in (38) can be represented as (39) where the specific form will be dependent on the choice of the weighting function , and is defined in Table I. The dipole moment can, therefore, be separated from the inner product, and for the basis functions we define an matrix such that (40) From (32), we see that the potential on any surface is, therefore (41) and the EEG forward problem is solved.…”

Expression for noninvasive measurement of internal map of local Joule heat consumption using acousto-electric effect

“…That is, the paired electrodes must be properly configured using a priori knowledge about the generated current source such that 'ðx; y; zÞj À r0ðx; y; z; tÞj 2 ] is approximately realized as in Eq. (6). Multiple configurations of paired electrodes should also be used.…”

“…Thus, our techniques enable us to evaluate the electric conductive paths of normal and cultured nerves as well as the electric properties of tissues (brain, heart, muscle, etc.). Similarly to other approaches [5][6][7][8][9][10][11], injected, excited and evoked currents can also be dealt with.…”

“…In such other approaches, various current dipole reconstruction techniques for the heart (e.g., [5,6]) and brain (e.g., [7]) using paired electrodes have been developed. Moreover, for the reconstruction of conductivity, in refs.…”