title: A 7T spine array based on electric dipole transmitters.
abstract: OBJECTIVE
  The goal of this study was to explore the feasibility of using an array of electric dipole antennas for RF transmission in spine MRI at high fields.
  
  
  METHODS
  A two-channel transmit array based on an electric dipole design was quantitatively optimized for 7T spine imaging and integrated with a receive array combining eight loop coils. Using B1+ mapping, the transmit efficiency of the dipole array was compared with a design using quadrature loop pairs. The radiofrequency energy deposition for each array was measured using a home-built dielectric phantom and MR thermometry. The performance of the proposed array was qualitatively demonstrated in human studies.
  
  
  RESULTS
  The results indicate dramatically improved transmit efficiency for the dipole design compared with the loop excitation. A gain of up to 76% was achieved within the spinal region.
  
  
  CONCLUSIONS
  For imaging of the spine, electric dipole-based transmitters provide an attractive alternative to the traditional loop-based design. Easy integration with existing receive array technology facilitates practical use at high fields.
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Qi
authors.initials: Q
authors.lastname: Duan
authors.affiliation: Division of Neuroimmunology and Neurovirology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Govind
authors.initials: G
authors.lastname: Nair
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Natalia
authors.initials: N
authors.lastname: Gudino
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Jacco A
authors.initials: JA
authors.lastname: de Zwart
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: van Gelderen
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Joe
authors.initials: J
authors.lastname: Murphy-Boesch
authors.affiliation: Division of Neuroimmunology and Neurovirology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Reich
authors.affiliation: Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Jeff H
authors.initials: JH
authors.lastname: Duyn
authors.forename: Hellmut
authors.initials: H
authors.lastname: Merkle
mesh_terms: D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods*; D019047:Phantoms, Imaging; D013131:Spine / Q000033:anatomy & histology*
keywords: dipole antenna; high field MRI; receive array; spinal imaging; transmit array