Comparison of ML and MAP parameter estimation techniques for the solution of inverse electrocardiography problem

Download

index.pdf

Date

2018

Author

Erenler, Taha

Metadata

Show full item record

Item Usage Stats

362
views

150
downloads

This study aims to determine the cardiac electrical activity from body surface potential measurements. This problem is called the inverse problem of electrocardiography. Reconstruction of the cardiac electrical activity from the body surface potential measurements is not an easy task, since this problem has an ill-posed nature due to attenuation and spatial smoothing inside the medium between the source and the measurement sites, meaning that even small errors in the mathematical model or noise in the measurements may yield unbounded errors or large oscillations in the solutions. One remedy for this ill-posedness is to apply regularization, where one imposes deterministic or statistical constraints on the solution based on available a priori information. In this thesis, Tikhonov regularization, Bayesian maximum a posteriori estimation (BMAP), Kalman filter and regularized Kalman filter approaches are used to solve the inverse problem of electrocardiography. In the context of Kalman filter, maximum likelihood (ML) and maximum a posteriori (MAP) estimation are used to find Kalman filter parameters. By estimating Kalman filter parameters, we aim to find an answer to an open question of how the essential parameters in the state-space representation are found without claiming strong assumptions in the literature. The results showed that the mean correlation coefficient ranges from 0.99 to 0.66 for MLIF and from 0.97 to 0.72 for MAPIF under 30 dB measurement noise. Our study showed that ML estimation works well when the training set data and test data are similar. However, due to over-fitting nature of the ML estimation, MAP estimation should be preferred in order to improve generalizability of the method.

Subject Keywords

Electrocardiography., Kalman filtering.

URI

http://etd.lib.metu.edu.tr/upload/12622779/index.pdf
https://hdl.handle.net/11511/27672

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Use of genetic algorithm for selection of regularization parameters in multiple constraint inverse ECG problem Mazloumi Gavgani, Alireza; Serinağaoğlu Doğrusöz, Yeşim; Department of Electrical and Electronics Engineering (2011) The main goal in inverse and forward problems of electrocardiography (ECG) is to better understand the electrical activity of the heart. In the forward problem of ECG, one obtains the body surface potential (BSP) distribution (i.e., the measurements) when the electrical sources in the heart are assumed to be known. The result is a mathematical model that relates the sources to the measurements. In the inverse problem of ECG, the unknown cardiac electrical sources are estimated from the BSP measurements and ...
Use of Activation Time Based Kalman Filtering in Inverse Problem of Electrocardiography Aydin, Umit; Serinağaoğlu Doğrusöz, Yeşim (2008-11-27) The goal of this study is to solve inverse problem of electrocardiography (ECG) in terms of epicardial potentials using body surface (torso) potential measurements. The problem is ill-posed and regularization must be applied. Kalman filter is one of the regularization approaches, which includes both spatial and temporal correlations of epicardial potentials. However, in order to use the Kalman filter, one needs the state transition matrix (STM) that models the time evolution of the epicardial potentials. In...
Lorentz Alanları ve Manyetik Alan Ölçümleri ile Elektriksel Empedans Görüntülemesi Gençer, Nevzat Güneri; Gözü, Soner Mehmet; Ghalichi, Elyar; Kaboutori, Keivan; Tetik, Önder Ahmet(2017) Bu projede sağlıklı/kanserli dokuların elektriksel empedanslarının görüntülenmesi içinelektromanyetik alanlar ile ultrasonun birleştiği hibrit bir yöntem önerilmiştir. Bu yöntem, statikmanyetik alan ortamında, doku yüzeyine yerleştirilen ultrasonik vericilerin yarattığı akustiktitreşimler sonucu oluşan Lorentz alanlarına dayanmaktadır. İletken cisim içinde yayılan buelektriksel alanlar dokuda ultrason yayılım hızıyla akımlar indüklemektedir. Bu akımyoğunluğundan (hız-akım yoğunluğu) kaynaklanan manyetik ala...
Evaluation of multivariate adaptive non-parametric reduced-order model for solving the inverse electrocardiography problem: a simulation study Onak, Onder Nazim; Serinağaoğlu Doğrusöz, Yeşim; Weber, Gerhard Wilhelm (Springer Science and Business Media LLC, 2019-05-01) In the inverse electrocardiography (ECG) problem, the goal is to reconstruct the heart's electrical activity from multichannel body surface potentials and a mathematical model of the torso. Over the years, researchers have employed various approaches to solve this ill-posed problem including regularization, optimization, and statistical estimation. It is still a topic of interest especially for researchers and clinicians whose goal is to adopt this technique in clinical applications. Among the wide range of...
Forward problem of electrocardiography in terms of 3D transmembrane potentials using COMSOL Bedir, Gizem; Serinağaoğlu Doğrusöz, Yeşim; Çetin, Barbaros; Department of Biomedical Engineering (2015) Computation of body surface potentials from equivalent cardiac sources is called as forward problem of electrocardiography (ECG). There exist different solution meth- ods for solving the forward ECG problem. These solution methods depend on the choice of the equivalent cardiac sources. In this study, bidomain model based trans- membrane potential (TMP) distribution is used as equivalent cardiac source to exam- ine the cellular electrophysiology macroscopically. With this type of source defini- tion, the TMP...

Citation Formats

T. Erenler, “Comparison of ML and MAP parameter estimation techniques for the solution of inverse electrocardiography problem,” M.S. - Master of Science, Middle East Technical University, 2018.