Japanese journal of medical electronics and biological engineering
Online ISSN : 2185-5498
Print ISSN : 0021-3292
ISSN-L : 0021-3292
Bias and Scatter in Estimation of the Dual Equivalent Cardiac Dipoles
Yoshiwo OKAMOTOMasanori AOKIToshimitsu MUSHAKen-ichi HARUMI
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1985 Volume 23 Issue 6 Pages 374-379

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Abstract
The equivalent cardiac dipole method has been investigated to estimate from a body surface potential distribution the location as well as the vector components of a dipole, which approximate the EMF sources in a heart. However, the single dipole approximation is not always valid, and two or more dipoles should be taken into account for complicated EMF sources.
To look into the accuracy of the estimation of two cardiac dipoles, we performed computer simulation with a three dimensional torso model. Several factors which affect the resultant equivalent dipoles, such as simplification of the human torso, noise in the measured potentials, fluctuations in the reference potential and displacements of the electrode locations, have been considered, and the following conclusions were obtained.
(1) To avoid a long computation time in case of clinical application, the human torso must be simplified to approximate such models as a semi-infinite region bounded by a plane, a sphere, or an infinite conductor in which the body is immersed. Among these, the infinite-medium model is most desirable.
(2) The infinite-medium model usually results in bias error ranging from 1cm to 3cm. However, a pair of dipoles located too close to each other are sometimes estimated at completely different positions.
(3) Except for rare occasions in which the estimated dipoles are far from their original locations, the dipole estimation error due to noise and offset voltage fluctuations is less than 5mm if they are 10% of the RMS of the body surface potential distribution.
(4) A 1cm error in electrode locations results in 2cm error in estimated dipole locations.
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© Japanese Society for Medical and Biological Engineering
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