title: Design of a nested eight-channel sodium and four-channel proton coil for 7T knee imaging.
abstract: The critical design aim for a sodium/proton coil is to maximize sodium sensitivity and transmit field homogeneity while simultaneously providing adequate proton sensitivity and homogeneity. While most dual-frequency coils use lossy high-impedance trap circuits or PIN diodes to allow dual-resonance, we explored a nested-coil design for sodium/proton knee imaging at 7 T. A stand-alone eight-channel sodium receive array was implemented without standard dual-resonance circuitry to provide improved sodium signal-to-noise ratio. A detunable sodium birdcage was added for homogeneous sodium excitation and a four-channel proton transmit-receive array was added to provide anatomical reference imaging and B0 shimming capabilities. Both additional modules were implemented with minimal disturbance to the eight-channel sodium array by managing their respective resonances and geometrical arrangement. In vivo sodium signal-to-noise ratio was 1.2-1.7 times greater in the developed eight-channel array than in a mononuclear sodium birdcage coil, whereas the developed four-channel proton array provided signal-to-noise ratio similar to that of a commercial mononuclear proton birdcage coil.
authors.affiliation: Department of Radiology, New York University Langone Medical Center, New York, New York 10016, USA. ryan.brown@nyumc.org
authors.forename: Ryan
authors.initials: R
authors.lastname: Brown
authors.forename: Guillaume
authors.initials: G
authors.lastname: Madelin
authors.forename: Riccardo
authors.initials: R
authors.lastname: Lattanzi
authors.forename: Gregory
authors.initials: G
authors.lastname: Chang
authors.forename: Ravinder R
authors.initials: RR
authors.lastname: Regatte
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Sodickson
authors.forename: Graham C
authors.initials: GC
authors.lastname: Wiggins
mesh_terms: D000465:Algorithms; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation*; D007719:Knee Joint / Q000033:anatomy & histology* / Q000737:chemistry*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D008280:Magnetics / Q000295:instrumentation*; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012964:Sodium / Q000032:analysis*
chemical_list: D011522:Protons; D012964:Sodium