NONFLUOROSCOPIC LOCALIZATION OF AN AMAGNETIC CATHETER IN A REALISTIC TORSO PHANTOM BY MAGNETOCARDIOGRAPHIC AND BODY-SURFACE POTENTIAL MAPPING

This study was performed to evaluate the accuracy of multichannel magn etocardiographic (MCG) and body surface potential mapping (BSPM) in lo calizing three-dimensionally the tip of an amagnetic catheter for elec trophysiology without fluoroscopy. An amagnetic catheter (AC), special ly designed to produce dipolar sources of different geometry without m agnetic disturbances, was placed inside a physical thorax phantom at t wo different depths, 38 mm and 88 mm below the frontal surface of the phantom. Sixty-seven MCG and 123 BSPM signals generated by the 10 mA c urrent stimuli fed into the catheter were then recorded in a magnetica lly shielded room. Noninvasive localization of the tip of the catheter was computed from measured MCG and BSPM data using an equivalent curr ent dipole source in a phantom-specific boundary element torso model. The mean S-dimensional error of the MCG localization at the closer lev el was 2 +/- 2 mm. The corresponding error calculated from the BSPM me asurements was 4 +/- 2 mm. At the deeper level, the mean localization errors of MCG and BSPM were 7 +/- 4 mm and 10 +/- 2 mm, respectively. The results showed that MCG and BSPM localization of the tip of the AC is accurate and reproducible provided that the signal-to-noise ratio is sufficiently high. In our study, the MCG method was found to be mor e accurate than BSPM. This suggests that both methods could be develop ed towards a useful clinical tool for nonfluoroscopic 3-dimensional el ectroanatomical imaging during electrophysiological studies, thus mini mizing radiation exposure to patients and operators.