title: Comparison of a 28-channel receive array coil and quadrature volume coil for morphologic imaging and T2 mapping of knee cartilage at 7T.
abstract: OBJECTIVE
  To compare a new birdcage-transmit, 28-channel receive array (28-Ch) coil and a quadrature volume coil for 7T morphologic MRI and T2 mapping of knee cartilage.
  
  
  METHODS
  The right knees of 10 healthy subjects were imaged on a 7T whole body magnetic resonance (MR) scanner using both coils. 3D fast low-angle shot (3D-FLASH) and multiecho spin-echo (MESE) sequences were implemented. Cartilage signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), thickness, and T2 values were assessed.
  
  
  RESULTS
  SNR/CNR was 17%-400% greater for the 28-Ch compared to the quadrature coil (P ≤ 0.005). Bland-Altman plots show mean differences between measurements of tibial/femoral cartilage thickness and T2 values obtained with each coil to be small (-0.002 ± 0.009 cm / 0.003 ± 0.011 cm) and large (-6.8 ± 6.7 msec/-8.2 ± 9.7 msec), respectively. For the 28-Ch coil, when parallel imaging with acceleration factors (AF) 2, 3, and 4 was performed SNR retained was: 62%-69%, 51%-55%, and 39%-45%.
  
  
  CONCLUSIONS
  A 28-Ch knee coil provides increased SNR/CNR for 7T cartilage morphologic imaging and T2 mapping. Coils should be switched with caution during clinical studies because T2 values may differ. The greater SNR of the 28-Ch coil could be used to perform parallel imaging with AF2 and obtain similar SNR as the quadrature coil.
authors.affiliation: Quantitative Multinuclear Musculoskeletal Imaging Group, Center for Biomedical Imaging, Department of Radiology, NYU Langone Medical Center, New York, New York 10016, USA. gregory.chang@nyumc.org
authors.forename: Gregory
authors.initials: G
authors.lastname: Chang
authors.forename: Graham C
authors.initials: GC
authors.lastname: Wiggins
authors.forename: Ding
authors.initials: D
authors.lastname: Xia
authors.forename: Riccardo
authors.initials: R
authors.lastname: Lattanzi
authors.forename: Guillaume
authors.initials: G
authors.lastname: Madelin
authors.forename: Jose G
authors.initials: JG
authors.lastname: Raya
authors.forename: Matthew
authors.initials: M
authors.lastname: Finnerty
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fujita
authors.forename: Michael P
authors.initials: MP
authors.lastname: Recht
authors.forename: Ravinder R
authors.initials: RR
authors.lastname: Regatte
mesh_terms: D000328:Adult; D002358:Cartilage, Articular / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio; D018709:Statistics, Nonparametric
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