The effect of geometric and topologic differences in boundary element models on magnetocardiographic localization accuracy

This study was performed to evaluate the changes in magnetocardiographic (M CG) source localization results when the geometry and the topology of the v olume conductor model were altered, Boundary element volume conductor model s of three patients were first constructed. These so-called reference torso models were then manipulated to mimic various sources of error in the meas urement and analysis procedures. Next, equivalent current dipole localizati ons were calculated from simulated and measured multichannel MCG data. The localizations obtained with the reference models were regarded as the "gold standard." The effect of each modification was investigated by calculating three-dimensional distances from the gold standard localizations to the lo cations obtained with the modified model. The results show that the effect of the lungs and the intra-ventricular blo od masses is significant for deep source locations and, therefore, the tors o model should preferably contain internal inhomogeneities. However, superf icial sources could be localized within a fen millimeters even with nonindi vidual, so called standard torso models. In addition, the torso model shoul d extend long enough in the pelvic region, and the positions of the lungs a nd the ventricles inside the model should be known in order to obtain accur ate localizations.