Phantom validation of multichannel magnetocardiography source localization

Multichannel Magnetocardiography (MMCG) is clinically used for non-invasive localization of cardiac arrhythmias. We have tested, in our EP cathlab, the 3D localization accuracy of MMCG, using a phantom (PH) filled with saline, and an amagnetic catheter (AC) designed for clinical multiple monophasic action potential recording. Methods: 9 channels system (sensitivity 20 fT/Hz1/2 at 1 Hz, measuring grid: 20 x 20 cm). AC dipole (5 mm length) placed 12 cm below the sensors plane. Equivalent current dipole (ECD) and distributed currents (CDI) models used for inverse solution. The localization error (LE) was estimated as the 3D difference between X-ray position and MMCG ECD localization of the AC. The reproducibility was tested by repositioning both the PH and the MMCG system. Results: With the ECD model the average LE of the AC dipole was 9 ± 4 mm. Most of the LE was due to unprecise depth estimation. The reproducibility was within 0.73 mm. CDI provided an accurate image of current flowing, centred at the PH site, where the tip of the AC was placed. Conclusion: MMCG localization of the AC dipolar source is reproducible in unshielded EP lab and can be used for non-fluoroscopic 3D imaging of the AC for electrophysiology