title: High-field MRSI of the prostate using a transmit/receive endorectal coil and gradient modulated adiabatic localization.
abstract: OBJECTIVE
  To demonstrate in vivo magnetic resonance spectroscopic imaging (MRSI) of the human prostate at 4.0T using a transmit/receive endorectal coil and a pulse sequence designed specifically for this application.
  
  
  METHODS
  A solid, reusable endorectal probe was designed for both radiofrequency transmission and reception. Finite difference time domain (FDTD) simulations were performed to characterize the coil's electric field distribution, and temperature measurements were performed in a beef tissue phantom to determine the coil's safe operating limit. The localization by selective adiabatic refocusing (LASER) pulse sequence was implemented using six gradient modulated offset independent adiabatic (GOIA) pulses for very sharp, B(1)-insensitive voxel localization.
  
  
  RESULTS
  Based on the simulations and temperature measurements, the coil's safe operating limit was conservatively estimated to be 1.0W for 15 minutes. The transition width of the GOIA pulse selection profiles was only 6% of the bandwidth, compared with 22% for a specific absorption rate (SAR)-matched conventional adiabatic pulse. Using the coil and pulse sequence described here, MRSI data were successfully acquired from a patient with biopsy-proven prostate cancer, with a nominal voxel size of 0.34 cc in a scan time of 15 minutes.
  
  
  CONCLUSIONS
  This work demonstrates the safe and effective use of a transmit/receive endorectal coil for in vivo MRSI of the prostate.
authors.affiliation: Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada.
authors.forename: Jamie
authors.initials: J
authors.lastname: Near
authors.forename: Cesare
authors.initials: C
authors.lastname: Romagnoli
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Curtis
authors.forename: L Martyn
authors.initials: LM
authors.lastname: Klassen
authors.forename: Jonathan
authors.initials: J
authors.lastname: Izawa
authors.forename: Joseph
authors.initials: J
authors.lastname: Chin
authors.forename: Robert
authors.initials: R
authors.lastname: Bartha
mesh_terms: D003198:Computer Simulation; D004869:Equipment Safety; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation* / Q000379:methods*; D008297:Male; D011467:Prostate / Q000473:pathology*; D011846:Radio Waves