Fusing Magnetocardiography (MCG) and Chest CT/X-ray for Functional-Anatomical Cardiac Mapping

A noninvasive and noncontact measurement of weak magnetic fields generated by the electrical activity of the heart is magnetocardiography (MCG). The spatial distribution of MCG signals measured over subjects’ chests by an array of detectors is plotted as a magnetic field map (MFM). MFMs aid in visualizing cardiac electrical activity as equivalent current dipole and facilitate localizing cardiac sources using inverse problem techniques. Fusing MFMs with the anatomical images of the chest is expected to provide a better conception of cardiac sources as a functional-anatomical mapping tool for clinical diagnosis. Exclusive descriptions of image fusion procedures applicable to MCG studies are only sparingly found. The present work details a methodology involving digitally matching, registering, and applying wavelet transform-based techniques to fuse MFM images generated using a 37-channel MCG array with already available anatomical images of subjects’ chests as computed tomographic (CT) or planar X-ray images. When tested on anatomical images taken from eighteen subjects with their respective MCG-MFM, the proposed framework exhibits the confinement of cardiac sources to be localized at plausible anatomical locations of the heart. The fused images are also qualitatively and quantitatively evaluated. These results encourage applying this image fusion framework for pre- and post-interventional assessments.