874-2 Reproducibility and interpretation of magneto-cardio-gram maps in detecting ischemia

Case report: Magnetocardiography as a potential method of therapy monitoring in amyloidosis

“…To date, the role of MCG has been investigated primarily in early diagnosis of ischemic heart disease (25)(26)(27)(28)(29). MCG has been reported as a potential diagnostic tool in coronary artery disease and myocardial infarction (30).…”

Unshielded magnetocardiography: Repeatability and reproducibility of automatically estimated ventricular repolarization parameters in 204 healthy subjects

“…Compared to previous studies (Chen et al., , ; Steinberg et al., , ; Tolstrup et al., ), a larger cohort, 204 normal subjects, has been investigated. Moreover, all subjects underwent at least two MCG recordings, carried out under variable conditions (i.e., different hours of the days, implying different intensity of the background electromagnetic noise) to check for repeatability and for reproducibility of data analysis performed with signals acquired in the “real‐life” of an unshielded hospital environment.…”

“…Quantitative analysis, based on the solution of the inverse problem with the effective magnetic dipole (EMD) model and automatic calculation of the time‐variant dynamics of: (1) the three‐dimensional (3D) EMD vector (EMDV) components and (2) of the T‐wave magnetic field (MF) extrema: EMDV parameters: The magnitude and strength of motion of the EMV can be described by seven predefined parameters T‐wave vector parameters calculated both before ( Ascending limb , or A ) and after ( Descending limb , or D ) the T‐wave peak: Two azimuth mean: the angles between the projection of 3D average EMDV on XY plane and the x‐axis, being the origin of the axes the vertex ( azimuth mean A normal if between −110° and −15 ° and azimuth mean D normal if between −100° and −22°); Two Trajectory Length: EMDV trajectory lengths ( Trajectory Length A normal if between 0 and 7.5 cm and Trajectory Length D normal if between 0 and 5 cm); Two Angle Derivative Range: 3D EMDV angular deviations (between T‐start and T‐peak and between T‐peak and T‐end) defined through azimuth and elevation (i.e., the angle between the projection of 3D average EMV on XZ plane and the x‐axis, being the origin of the axes the vertex) ( angle derivative range A normal if between 0 and 1.0 radians and angle derivative range D normal if between 0 and 0.7 radians); The azimuth difference (A–D): angular displacement, with its own orientation, on XY plane, of the projection of 3D average EMDV (i.e., azimuth mean A minus azimuth mean D ), normal if between −35° and 12°; T‐wave extrema MF dynamics: five parameters automatically calculated during the first phase of VR, within a frame of 30 ms moving into an interval between the point where MF strength is equal to 1/3 of T‐wave peak MF and the T‐wave peak. Being generated, for each millisecond, an instant magnetic map with a positive and a negative pole (the highest and the lowest intensity of the MF) (Fenici, Brisinda, Meloni, Sternickel, & Fenici, ; Park & Jung, ; Steinberg et al., , ), the following parameters were calculated: Two angle extrema: maximum ( angle extrema 1 ) and minimum ( angle extrema 2 ) α angle between a line through the poles and a horizontal line, the origin set to plus pole (normal if between −110° and 20°); The angle dynamics: α angle rotation in each interval of 30 ms (abnormal if >45°); The distance dynamics: dynamic change of the distance between the poles ± (abnormal if >20 mm); The ratio dynamics: MF strength ratio between the poles ± (abnormal if >0.3). …”

“…Although a direct comparison among different MCG systems and standardization of analytic methods is still missing, some attempts to standardize MCG format and to assess reproducibility and age‐ or gender‐dependent variations of several MCG parameters (e.g., interval durations, waveforms, VR dipole motion, vector parameters) have been reported (Chen et al., ; Kandori, Ogata, Miyashita, Watanabe et al., ; Lim et al., ; Steinberg et al., ). Given the availability of a unique multichannel MCG instrumentation fully operational into our unshielded hospital laboratory for interventional electrophysiology since 2002 (Fenici, Brisinda, & Meloni ; Fenici, Brisinda, Meloni, Sternickel, & Fenici, ; Fenici et al., , ), we have retrospectively selected and analyzed MCG data of 204 healthy subjects to assess the repeatability and reproducibility of automatically calculated VR parameters used for diagnosis of IHD (Bakharev, ; Kwong et al., ; Park & Jung, ; Steinberg et al., , ; Tolstrup et al., ), to set up a normality database obtained with simultaneous mapping (Fenici, Brisinda, Meloni, & Fenici, ), from a larger cohort compared to previous studies (Chen et al., , ; Hailer, Van Leeuwen et al., ; Tolstrup et al., ) and to evaluate gender‐ and/or age‐related variability.…”