Development of reconstruction algorithms for magnetic resonance-electrical impedance tomography and experimental realization

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2002

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Birgül, Özlem

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The electrical properties of biological tissues differ among tissues and vary with physiological and pathological state of a solution of bioelectrical field problems. The aim of this study is to reconstruct conductivity images with higher resolution and better accuracy than existing conductivity imaging tech niques. In order to achieve our goal, we proposed a technique named as Mag netic Resonance-Electrical Impedance Tomography (MR-EIT). MR-EIT com bines peripheral voltage measurements of classical Electrical Impedance To mography (EIT) technique with magnetic flux density measurements acquired using Magnetic Resonance Imaging (MRI) technique. Three reconstruction algorithms for MR-EIT are developed and implemented. Proposed algorithms are grouped into two: current density based reconstruction algorithms ( Type-I) and magnetic flux density based reconstruction algorithms {Type-It). Type-I al- iiigorithms require measurement of magnetic flux density in three directions and rotation of the object in the magnet, whereas measurement of only one com ponent of the magnetic flux density for a single rotation is sufficient for Type- II. Different current injection profiles are studied and their performance are compared. Distinguishability analysis is carried out for magnetic flux density measurements. The technique is experimentally realized using 0.15T METU- EE MRI system and several images are reconstructed for phantoms built using saline solution. In the experimental results, a Type-II algorithm is used and the error in reconstructed conductivity is found to be between 4.15% - 17.7% for saline. Comparison of the new technique with conventional EIT reconstruction using simulation data sets exhibits the superiority of MR-EIT.

Subject Keywords

Magnetic resonance imaging, Electrical impedance tomography, Electrophysiology

URI

https://hdl.handle.net/11511/13026

Collections

Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

Ö. Birgül, “Development of reconstruction algorithms for magnetic resonance-electrical impedance tomography and experimental realization,” Ph.D. - Doctoral Program, Middle East Technical University, 2002.