Discrimination between Myocardial Infarct Groups through the Use of Iso-Integral Magnetic Field Maps
John Lant, G. Stroink, T J Montague, Martin J. Gardner, Marek Mieszkowski · American Journal of Noninvasive Cardiology · 2017
Magnetocardiograms (MCG) for a study group of 22 myocardial infarct (MI) patients and for 22 normal subjects were recorded. For each individual, sets of time-integral magnetic field maps (MFM) were constructed from MCGs obtained in a plane parallel and proximal to the anterior torso. For each time interval, the group-mean normal map was subtracted from the corresponding MI group-mean time-integral maps, resulting in the creation of mean difference (residual) maps; these contain positive and negative areas of difference which are subsequently used to demarcate identical regions within the individual maps of the group members. Average time-integral values are calculated for these map regions. Intergroup comparison of these values, using t test for unpaired observations, determines the significance of differences in group-mean maps. Results indicate that MCG discriminates between populations on the basis of iso-integral MFM and that there exist particular time intervals in which differentiation is most pronounced. The Q-wave and Q-zone intervals are useful in defining or recognizing patients with non-Q-wave and/or anterior MI; inferior MI patients are best identified using T-wave interval MFM. Further evidence of the usefulness of iso-integral MFM in discriminating between MI groups derives from a study of the map loci of signal extrema and their torso distributions. Torso distribution of depolarization integral extrema clearly separates anterior MI and non-Q-wave MI patients from normals while torso distribution of T-wave extrema effectively differentiates inferior MI patients from normals.