title: Dual-frequency, dual-quadrature, birdcage RF coil design with identical B1 pattern for sodium and proton imaging of the human brain at 1.5 T.
abstract: Rapid quantification of tissue metabolites in vivo by MRS or MRI can be achieved using dual-frequency RF coils with identical B1 field distributions at the observation frequencies of the metabolites and tissue water protons. Tissue sodium is used as an example for optimizing the dual-frequency, dual-quadrature RF coils for such measurements in humans. In the setting of sodium imaging, the challenge of dual-quadrature birdcage configurations is to decouple the sodium and proton channels because the fourth harmonic of the sodium frequency is very close to the proton frequency. A generalizable method for effectively decoupling these two RF frequencies is presented in this paper. The method is demonstrated with the design of an EPI compatible, dual-quadrature, double-tuned, 23Na/1H birdcage coil. The performance of the RF probe is reported at 1.5 Tesla in terms of signal-to-noise ratio, B1 homogeneity and image quality.
authors.affiliation: Department of Radiology, University of Pittsburgh Medical Center, PA 15213, USA.
authors.forename: G X
authors.initials: GX
authors.lastname: Shen
authors.forename: F E
authors.initials: FE
authors.lastname: Boada
authors.forename: K R
authors.initials: KR
authors.lastname: Thulborn
mesh_terms: D001921:Brain / Q000033:anatomy & histology* / Q000378:metabolism; D017352:Echo-Planar Imaging; D004867:Equipment Design; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation; D019047:Phantoms, Imaging