B1 + phase retrieval for non-quadrature radio frequency excitation and its preliminary application in MR-EPT

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buir.contributor.authorArıtürk, Gökhan
buir.contributor.authorİder, Yusuf Ziya
dc.citation.epage11en_US
dc.citation.issueNumber2en_US
dc.citation.spage1en_US
dc.citation.volumeNumber64en_US
dc.contributor.authorArıtürk, Gökhanen_US
dc.contributor.authorİder, Yusuf Ziyaen_US
dc.date.accessioned2020-02-05T13:46:10Z
dc.date.available2020-02-05T13:46:10Z
dc.date.issued2019-01
dc.departmentDepartment of Electrical and Electronics Engineeringen_US
dc.description.abstractNon-quadrature radio frequency (RF) excitation has been widely studied in the fields of RF shimming, local SAR estimation, and MR-EPT with the use of multi-channel transceiver arrays. These studies generally require the retrieval of the complex transmit field ( ), which can be accomplished by acquiring its magnitude and phase in different steps. Magnitude of the transmit field is acquired with the conventional methods which give accurate results for both quadrature and non-quadrature excitations. On the other hand, there is no straightforward method to acquire the absolute phase of the transmit field and generally approximations in MRI experiments are made in order to get it. However, many of these approximations fail in non-quadrature excitation and/or in ultra high fields. In this study, we propose a simple method to acquire the absolute transmit phase in non-quadrature excitation with an eight channel transceiver TEM array for 3 T. The proposed method requires the application of a single additional quadrature drive in order to get the receive phases of the individual channels of the transceiver coil. These receive phases are then subtracted from the transceive phase of the non-quadrature drive experiment to acquire its transmit phase. The developed ideas are tested in the framework of simulations and MRI experiments with the use of four different non-quadrature drive configurations. It has been observed that the simulated and experimentally acquired transmit phase distributions tend to have a strong consensus which supports the validity of the proposed method. Finally, the estimated transmit phase distribution of non-quadrature drive is used in the standard MR-EPT study to get the conductivity reconstructions in order for the validation of its eligibility in MR-EPT studies.en_US
dc.identifier.doihttps://dx.doi.org/10.1088/1361-6560/aaf7been_US
dc.identifier.doi10.1088/1361-6560/aaf7be
dc.identifier.eissn1361-6560
dc.identifier.issn0031-9155
dc.identifier.urihttp://hdl.handle.net/11693/53099
dc.language.isoEnglishen_US
dc.publisherInstitute of Physics and Engineering in Medicineen_US
dc.relation.isversionofhttps://dx.doi.org/10.1088/1361-6560/aaf7been_US
dc.source.titlePhysics in Medicine & Biologyen_US
dc.subjectB+ 1 phase acquisitionen_US
dc.subjectNon-quadrature excitationen_US
dc.subjectMR-EPTen_US
dc.subjectMultichannel RF transmissionen_US
dc.subjectTEM transceiver arrayen_US
dc.subjectB1 shimmingen_US
dc.titleB1 + phase retrieval for non-quadrature radio frequency excitation and its preliminary application in MR-EPTen_US
dc.typeArticleen_US
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