Author + information
- Illya Chaikovsky1,2,
- Mykhail Primin2,
- Igor Nedayvoda2,
- Andrey Verba1,
- Georg Mjasnikov1,
- Anatoly Kazmirchyk2,
- Wenmig Ji3,
- X. Fan4,
- X. Tan4,
- M. Lei4 and
- Z. Fan4
- 1Main Clinical Military Hospital of Ukraine, Kiev, Ukraine
- 2Institute of Cybernetics, Kiev, Ukraine
- 3Oxford Cardiomox Ltd., Oxford, United Kingdom
- 4Key Laboratory of Medical Electrophysiology, Ministry of Education, Institute of Cardiovascular Research of Southwest Medical University, Luzhou, Sichuan, China
Magnetocardiography (MCG) is a highly reliable non-invasive technique that measures the magnetic field generated by the electrical activity of the heart. Previous studies on MCG have shown high sensitivity in detecting myocardial ischemia, especially in cases of inverse problem solution usage, e.g. 3D reconstruction of current density distribution. The bull's-eye image, also called polar map image, has been developed to visualize and to quantitate analysis of tomographic slices. The objective of this research is to evaluate whether bull's-eye image of current density distribution is useful in detecting wall motion abnormalities in patients with coronary artery disease.
17 coronary artery disease patients without prior to myocardial infarction(mean age 52.3 ± 17.1 years)underwent dobutaminstress-echocardiography (DSE) and magnetocardiography (MCG) tests. A group of 27 healthy volunteers(mean age 41.5 ± 9 years) served as control subjects. Echocardiographic analysis of the left ventricular (LV) wall was performed according to the simplified 5-segment model, where each segment corresponded to anterior, lateral, inferior-posterior walls of LV, septal and apical zones, respectively. Systolic wall thickening and inward endocardial motion were visually evaluated, and each segment was graded on a 4-point scoring system (1 - normal; 2 - mild hypokinesis; 3 - severe hypokinesis; 4 - akinesis or dyskinesis). The MCG examination was performed using a 9-channel MCG, recording from 36 positions over the chest, in an unshielded environment. Algorithm of inverse solution for planar current distribution,based on double integral Fourier transform, was developed. Three-dimensional surface in the form of ellipsoid was used as a physical model to represent the current density, which was presented in the form of five-segment bull’s-eye maps. Similar to the DSE analysis, MCG used a 4-point scoring system to evaluate the current density (1 - normal; 2-mild density reduction; 3- moderate density reduction; 4 - severe density reduction). Finally, the agreement between assignment of LV segments, obtained from DSE and MCG using 4-points scoring system, was assessed using inter-rater agreement statistic (kappa, k).
The general correspondence between DSE and MCG analysis was 64%, k=0.5. High agreements were observed at the anterior (74%, k=0.61) and at the apical (71%, k=0.57) segments of LV. The agreement in inferior-posterior wall was observed to be significantly lower than the rest of the segments (39%, k=0.35).
The presence of wall motion abnormalities in anterior and apical segments of left ventricle in CAD patients lead to decreases in the current density in these areas of LV. Therefore, 3D reconstruction of current density using MCG can be a useful tool in obtaining important diagnostic information.