Magnetic resonance electrical impedance tomography based on MRI-SPAMM

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Elektrik ve Elektronik Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2016

Öğrenci: KEMAL SÜMSER

Danışman: BEHÇET MURAT EYÜBOĞLU

Özet:

Electrical conductivity of biological tissues differs among different kinds of tissues. Information about measured impedance of a tissue gives great deal of information about pathological state of the tissue and some biomedical applications requires this information. Magnetic Resonance Current Density Imaging (MRCDI) and Magnetic Resonance Electrical Impedance Tomography (MREIT) are two imaging modalities which investigates current and conductivity distribution inside objects by utilizing the magnetic flux density distribution induced by externally applied currents. Spatial Modulation of Magnetization (SPAMM) is a pre-imaging pulse sequence which is used to evaluate spatially dependent properties of an imaged object. Standard MREIT pulse sequences have long repetition times and this results in long acquisition times. Long acquisition times make imaging susceptible to artefacts. This problem can be overcomed by injecting current during a pre-imaging sequence and usage of pulse sequences with low repetition times. The aim of this study is to implement a new data acquisition sequence for MRCDI and MREIT applications. Spin Echo (SE) and Gradient Echo (GE) based SPAMM pulse sequences are implemented and tested on different experimental phantoms. Magnetic flux density data are obtained using this new technique. Current density and conductivity distributions are calculated. Noise levels and minimum measurable current level with proposed sequences are measured. SPAMM based pulse sequences are found to be applicable to MRCDI and MREIT studies and can help to reduce data acquisition times.