title: Development and evaluation of a multichannel endorectal RF coil for prostate MRI at 7T in combination with an external surface array.
abstract: To develop and evaluate a sterilizable multichannel endorectal coil (ERC) for use in combination with an external surface array (ESA) for high-resolution anatomical and functional studies of the prostate at 7T.
  
  
  
  A two-loop ERC (ERC-2L) and a microstrip-loop ERC (ERC-ML) were compared at 7T in terms of transmit and receive performance. The best-performing ERC was evaluated alone and in combination with the ESA through 1) simulations on both phantom and an anatomically correct numerical human model to assess B1+ transmit and specific absorption rate (SAR) efficiencies, and 2) phantom experiments to calculate B1+ transmit efficiency and signal-to-noise ratio (SNR). Phantom studies were also performed to look at heating when using the ERC as a transmitter and for comparing the new coil against a single-channel balloon-type ERC (ERC-b). High-resolution magnetic resonance imaging (MRI) acquisitions were performed on a single healthy subject using the two-channel ERC combined with the ESA.
  
  
  
  Compared to the ERC-ML, the ERC-2L demonstrated 20% higher SAR efficiency and higher SNR 3 cm from the coil. The presence of a tuned and detuned ERC-2L did not alter the peak local SAR of the ESA alone; however, the detuned ERC-2L had 45% less peak local SAR around the rectum compared to the tuned ERC-2L. The receive-only version of the ERC-2L improved the SNR 4.7-fold and 1.3-fold compared to the ESA and ERC-b, respectively. In combination with the ESA, the ERC-2L supported in-plane voxel-size of 0.36 × 0.36 mm(2) in T2 -weighted anatomic imaging.
  
  
  
  The reusable ERC-2L combined with an ESA offers a high SNR imaging platform for translational studies of the prostate at 7T. J. Magn. Reson. Imaging 2016;43:1279-1287.
authors.affiliation: Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, Minnesota, USA.
authors.forename: M Arcan
authors.initials: MA
authors.lastname: Ertürk
authors.affiliation: Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, Minnesota, USA.
authors.forename: Jinfeng
authors.initials: J
authors.lastname: Tian
authors.affiliation: Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, Minnesota, USA.
authors.forename: Pierre-François
authors.initials: PF
authors.lastname: Van de Moortele
authors.affiliation: Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, Minnesota, USA.
authors.forename: Gregor
authors.initials: G
authors.lastname: Adriany
authors.affiliation: Center for Magnetic Resonance Research, University of Minnesota Medical School, Minneapolis, Minnesota, USA.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Metzger
mesh_terms: D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008280:Magnetics / Q000295:instrumentation; D008297:Male; D019047:Phantoms, Imaging; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers
keywords: 7 Tesla body imaging; MRI; endorectal coil; prostate; prostate cancer; ultrahigh field