N.V. Seleznev – Post-graduate Student, Department “Medical and Technical Information Technologies”,  Bauman Moscow State Technical University

E-mail: seleznev.nv@bk.ru

A.N. Tihomirov – Senior Lecturer, Department “Medical and Technical Information Technologies”,  Bauman Moscow State Technical University. 

E-mail: aleksey.tihomirov@gmail.com

A.N. Briko – Senior Lecturer, Department “Medical and Technical Information Technology” (BMT-2),  Bauman Moscow State Technical University

E-mail: briko@bmstu.ru

S.I. Shchukin – Dr. Sc. (Eng.), Professor, 

Head of Department “Medical and Technical Information Technologies” (BMT-2),  Bauman Moscow State Technical University.

E-mail: schookin@mx.bmstu.ru 

The multichannel electrical impedance precordial method of cardiography potentially allows to expand opportunities of classical transthoracic rheocardiography, making it possible to obtain local displacements of the heart walls, to evaluate the displacements of the heart's blood mass center. However, the use of a geometric model based on a spherical inclusion in solving the problem of inverse impedancemetry does not always provide the necessary accuracy in determining hemodynamic characteristics. And the use of a sphere as an inclusion does not provide sufficient accuracy in approximating heart blood. In this study, geometric models based on spherical and elliptical inclusions are compared, and the accuracy of approximation by these geometric models is considered.

The purpose of this work was to compare the existing geometric model used to solve the problem of inverse electroimpedancemetry in the technology of computer multichannel electri-cal impedance cardiography with geometric models based on elliptical inclusion. The accuracy of the real heart geometry approximation by the proposed geometric models was estimated based on a comparison of the volumes of the approximating model and the real 3D heart blood model.

3D heart blood models were isolated according to computed tomography data for 4 healthy volunteers of different body types, namely asthenic, normosthenic and hypersthenic body types. Geometric models were evaluated for inspiratory and expiratory CT data, and at time points before the onset of systole and after the end of ventricular systole.

As a result, 3D models of blood filling the heart obtained from multispiral computed tomography (MSCT) data were approximated for asthenic, normosthenic and hypersthenic volunteers in various phases of respiration and cardiac activity. The analysis of errors in various approximation methods showed which geometric models should be used in solving the inverse problem of electroimpedance measurement and for which body type. Using a more complex geometric model increases the variable parameters, but reduces the approximation error. 

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