Development of image reconstruction algorithms for three dimensional magnetic resonance-electrical impedance tomography
Author(s)
Advisor
İder, Y. ZiyaDate
2003Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
The electrical resistivity of biological tissues differ among various tissue types.
Human body has a large resistivity contrast between a wide range of its tissues.
The aim of this study is to reconstruct conductivity images of three
dimensional objects with higher resolution and better accuracy than existing
conductivity imaging techniques. In order to achieve our goal, we proposed a
technique named as Magnetic Resonance - Electrical Impedance Tomography
(MR-EIT) which combines the peripheral voltage measurements of classical
Electrical Impedance Tomography (EIT) technique with magnetic flux density
measurements acquired using a Magnetic Resonance Imaging (MRI) scanner.
Five reconstruction algorithms are proposed and computer simulations are made.
The proposed algorithms fall in two categories those that utilize current density
data and those that utilize magnetic flux density data directly. The first group of
algorithms get the current density data from magnetic flux density by Ampere’s
law. For calculation of current density with Ampere’s law, we need to all three
components of magnetic flux density but that is not possible to get all of them
in one measurement phase. Total of three measurement phases are needed for
getting all of them but this is not practical because, for measurement of each
component the object has to be rotated appropriately in the MRI scanner. The
algorithms in the second group suggest an exit to this difficulty and achieve the
conductivity reconstruction by using only the data which was acquired in one
measurement phase. As can be seen in the results, conductivity reconstruction of
three dimensional objects on tomographic planes are made successfully with all
of the algorithms. They also work fine against to the measurement noise up to
an acceptable level.
Keywords
Magnetic Resonance - Electrical Impedance TomographyFinite Element Method
Image Reconstruction
Impedance Imaging
Current Density Imaging
Magnetic Resonance Imaging