Experimental studies for LFEIT with magnetic field measurements

Date

2018

Author

Tetik, Ahmet Önder

Metadata

Show full item record

Item Usage Stats

247
views

0
downloads

Lorentz Force Electrical Impedance Tomography based on magnetic field measurements (LFEIT) is a hybrid imaging modality to image the electrical impedance of body tissues. In this modality, ultrasound pressure waves applied to the body tissues under static magnetic fields induce Lorentz currents. Magnetic flux density due to these currents is measured using receiver coils. The main aim of this thesis is to develop an experimental setup and a data acquisition system to obtain LFEIT sig nals from phantoms. Moreover, conductivity contrast images are formed using the measured LFEIT signals. For the data acquisition system, custom made contactless receiver coils in Helmholtz configuration are utilized and a two-stage cascaded amplifier is designed to obtain LFEIT signals. A magnetic field generator is built with permanent magnets to apply 0.56 T static magnetic field to phantoms in the experimental setup. In addition, 16-element Linear Phased Array (LPA) Transducer is used to steer ultrasound waves in the phantoms. Two different phantoms are prepared for experiments. In the first experiment, a conductive inhomogenity with 3 S/m conductivity is detected at 92 mm from the transducer surface. The last experiment is conducted with a phantom including sunflower oil and agar-gel having a cavity filled with 58 S/m solution. The transducer steers ultrasound waves from -20◦ to 20◦ with 1◦ step angle in the phantom. At each angle, data acquisition system records LFEIT signals. With this system, 58 S/m cavity with 15.15 mm height, 30 mm width and 20 mm length dimensions is detected at a depth of 75 mm. As a result, conductivity contrast image of this phantom is formed using LFEIT signals. 3 S/m is the lowest conductivity detected by this technique compared to the previous studies reported in the literature.

Subject Keywords

Tomography., Magnetic fields., Ultrasonic imaging.

URI

http://etd.lib.metu.edu.tr/upload/12622788/index.pdf
https://hdl.handle.net/11511/27667

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Data acquisition system for Lorentz force electrical impedance tomography using magnetic field measurements Kaboutari, Keivan; Gençer, Nevzat Güneri; Department of Electrical and Electronics Engineering (2017) Lorentz Force Electrical Impedance Tomography (LFEIT) is a novel imaging modality to image electrical conductivity properties of biological tissues. This modality is recently proposed for early stage diagnosis of cancerous tissues. The main aim of this thesis study is to develop a data acquisition system for LFEIT. Design of contactless receiver sensor, static magnetic field generation (0.56 T is generated by permanent neodymium magnets), amplification of received signals and experimental studies using vari...
Radial motion of highly conducting sphere in magnetic field Gurcan, OD; Mirnov, VV; Ucer, D (2000-05-01) Radial motion of a highly conducting sphere in external magnetic field is considered. It both perturbs the external magnetic field and generates an electric field. Exact analytic solution has been obtained previously for a uniformly expanding sphere. In the present paper a new exact solution is derived which is valid not only for expansion but for contraction as well. It allows us to calculate analytically the total electromagnetic energy irradiated by the sphere involved in periodical radial motion with ar...
Experimental results for 2D magnetic resonance electrical impedance tomography (MR-EIT) using magnetic flux density in one direction Birgul, O; Eyüboğlu, Behçet Murat; Ider, YZ (IOP Publishing, 2003-11-07) Magnetic resonance electrical impedance tomography (MR-EIT) is an emerging imaging technique that reconstructs conductivity images using magnetic flux density measurements acquired employing MRI together with conventional EIT measurements. In this study, experimental MR-EIT images from phantoms with conducting and insulator objects are presented. The technique is implemented using the 0.15 T Middle East Technical University MRI system. The dc current method used in magnetic resonance current density imaging...
Experimental Realization of Single Current Diffusion Tensor Magnetic Resonance Electrical Impedance Tomography Sadighi, Mehdi; Şişman, Mert; Açıkgöz, Berk Can; Eyüboğlu, Behçet Murat (2020-08-08) To obtain low-frequency anisotropic conductivity distribution of biological tissues recently Diffusion Tensor Magnetic Resonance Electrical Impedance Tomography (DT-MREIT), which is combination of DTI and MREIT techniques, is proposed. There are two in vivo applications of DT-MREIT in the literature where two linearly independent current injection patterns are used. Decreasing the number of current injection patterns to one improves the feasibility of DT-MREIT in clinical applications. In this study, DT-MRE...
Practical Realization of Magnetic Resonance Conductivity Tensor Imaging (MRCTI) DEĞİRMENCİ, EVREN; Eyüboğlu, Behçet Murat (2013-03-01) Magnetic resonance conductivity tensor imaging (MRCTI) is an emerging modality which reconstructs images of anisotropic conductivity distribution within a volume conductor. Images are reconstructed based on magnetic flux density distribution induced by an externally applied probing current, together with a resultant surface potential value. The induced magnetic flux density distribution is measured using magnetic resonance current density imaging techniques. In this study, MRCTI data acquisition is experime...

Citation Formats

A. Ö. Tetik, “Experimental studies for LFEIT with magnetic field measurements,” M.S. - Master of Science, Middle East Technical University, 2018.