title: Magnetic field sensitivity at 7-T using dual-helmholtz transmit-only coil and 12-channel receive-only bended coil.
abstract: The purpose of this study was to combine a dual-Helmholtz (DH) transmit (Tx)-only coil and 12-channel receive (Rx)-only bended phased array (PA) coil to improve the magnetic flux (|B1|) sensitivity in the superior-to-inferior (S-I) direction during human brain magnetic resonance imaging (MRI) at 7-T. The proposed coil combination was primarily implemented by electromagnetic (EM) simulation and compared with the 16-leg birdcage coil and 8-channel PA coil, which are generally used for the Tx- and Rx-only modes, respectively. The optimal coil combinations for the proposed structure were determined by |B1| field calculations using the |BT+| and |BR-| fields, which are respectively the transmit and receive components of the |B1| field. The coil performance was then evaluated by a bench test and 7-T MRI experiment. The results of the computational calculations indicated that the |BT+| field of the DH coil was distributed similarly to that of the 16-leg birdcage coil despite the fewer conducting legs of the former. However, the 12-channel Rx-only bended PA coil had clearly higher |BR-| profiles compared to the 8-channel PA coil. The results of the 7-T in vivo experiment showed that the proposed combination of the DH Tx-only coil and 12-channel Rx-only bended PA coil had better |B1| field homogeneity in the sagittal slice as well as higher |B1| field sensitivity during human brain MRI compared to an 8-channel Rx-only PA coil. SCANNING 38:515-524, © 2015 Wiley Periodicals, Inc.
authors.affiliation: Neuroscience Research Institute, Gachon University, Incheon, Korea.
authors.forename: Kyoung-Nam
authors.initials: KN
authors.lastname: Kim
authors.affiliation: Department of Health Sciences and Technology, Gachon Advanced Institute for Health Sciences and Technology, Gachon Univeristy, Incheon, Korea.|Department of Radiological Science, Gachon University, Incheon, Korea.
authors.forename: Yeunchul
authors.initials: Y
authors.lastname: Ryu
authors.affiliation: Neuroscience Research Institute, Gachon University, Incheon, Korea.
authors.forename: Jeung-Hoon
authors.initials: JH
authors.lastname: Seo
authors.affiliation: Department of Neurosurgery, Gil Medical Center, Gachon University, Incheon, Korea.
authors.forename: Young-Bo
authors.initials: YB
authors.lastname: Kim
keywords: MRI; bended; birdcage coil; dual-Helmholtz coil; magnetic flux; phased array coil