title: Stepped impedance resonators for high-field magnetic resonance imaging.
abstract: Multi-element volume radio-frequency (RF) coils are an integral aspect of the growing field of high-field magnetic resonance imaging. In these systems, a popular volume coil of choice has become the transverse electromagnetic (TEM) transceiver coil consisting of microstrip resonators. In this paper, to further advance this design approach, a new microstrip resonator strategy in which the transmission line is segmented into alternating impedance sections, referred to as stepped impedance resonators (SIRs), is investigated. Single-element simulation results in free space and in a phantom at 7 T (298 MHz) demonstrate the rationale and feasibility of the SIR design strategy. Simulation and image results at 7 T in a phantom and human head illustrate the improvements in a transmit magnetic field, as well as RF efficiency (transmit magnetic field versus specific absorption rate) when two different SIR designs are incorporated in 8-element volume coil configurations and compared to a volume coil consisting of microstrip elements.
authors.forename: Can E
authors.initials: CE
authors.lastname: Akgun
authors.forename: Lance
authors.initials: L
authors.lastname: DelaBarre
authors.forename: Hyoungsuk
authors.initials: H
authors.lastname: Yoo
authors.forename: Sung-Min
authors.initials: SM
authors.lastname: Sohn
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Snyder
authors.forename: Gregor
authors.initials: G
authors.lastname: Adriany
authors.forename: Kamil
authors.initials: K
authors.lastname: Ugurbil
authors.forename: Anand
authors.initials: A
authors.lastname: Gopinath
authors.forename: J Thomas
authors.initials: JT
authors.lastname: Vaughan
mesh_terms: D003198:Computer Simulation; D017097:Electric Impedance; D004574:Electromagnetic Fields; D004867:Equipment Design; D006257:Head / Q000033:anatomy & histology / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods*; D019047:Phantoms, Imaging