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dc.contributor.advisorAtalar, Ergin
dc.contributor.authorSalim, Maryam
dc.date.accessioned2016-06-08T12:56:29Z
dc.date.available2016-06-08T12:56:29Z
dc.date.copyright2016-05
dc.date.issued2016-05
dc.date.submitted2016-06-08
dc.identifier.urihttp://hdl.handle.net/11693/29151
dc.descriptionCataloged from PDF version of article.en_US
dc.descriptionIncludes bibliographical references (leaves 49-52).en_US
dc.descriptionThesis (M.S.): Bilkent University, Department of Electrical and Electronics Engineering, İhsan Doğramacı Bilkent University, 2016.en_US
dc.description.abstractIn this thesis a new method for decoupling of RF transmit and receive coils in MRI is presented. A modified version of isolation concept used in the full-duplex radios in communication systems is applied to acquire MRI signal using concurrent excitation and acquisition (CEA) method. Since in MRI transmit power is many orders of magnitude larger than receive signal, a weak coupling might dominate the MR signal during CEA in MRI. In our new method, a small copy of RF transmit signal is attenuated and delayed to generate the same coupling signal which is available in the receiver coil then it is subtracted from the receive signal in order to detect the MRI signal. The proposed decoupling method is developed and implemented in two designs. First a semi-automatic controllable decoupling design which uses a programmable attenuator and coaxial cables for the purpose of time delay. After estimating the length of coaxial cables an optimization algorithm finds the amount of attenuation factor. Using this method we could achieve more than 75 dB decoupling. Second design is a fully-automatic controllable decoupling design which contains four delay and attenuator lines. In this design four fixed phase shifters are used in order to generate the same phase delay between transmit and receive coils. A genetic optimization algorithm is used to find the amount of attenuation factors of each line. It is shown that this method provides more than 100 dB decoupling between transmit and receive coils which is good enough for detecting MRI signals during excitation from tissues with very short relaxation time. This study shows feasibility of applying full duplex electronics which is used in telecommunications, to decouple transmit and receive coils for MRI with CEA, using a clinical MRI system. This device can automatically tune the cancellation circuit and it is a potential tool for recovering signal from tissues with extremely short T2 in clinical MR systems.en_US
dc.description.statementofresponsibilityby Maryam Salim.en_US
dc.format.extentxviii, 59 leaves : charts.en_US
dc.language.isoEnglishen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectMRIen_US
dc.subjectCEAen_US
dc.subjectDecouplingen_US
dc.subjectFull-Duplexen_US
dc.titleFull-duplex MRI for zero TE imagingen_US
dc.title.alternativeSıfır eko-zamanı görüntüleme için tam çift yönlü MRG kullanımıen_US
dc.typeThesisen_US
dc.departmentDepartment of Electrical and Electronics Engineeringen_US
dc.publisherBilkent Universityen_US
dc.description.degreeM.S.en_US
dc.identifier.itemidB153453
dc.embargo.release2017-01-01


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