title: MR thermometry in the human prostate gland at 3.0T for transurethral ultrasound therapy.
abstract: OBJECTIVE
  To investigate the spatial, temporal, and temperature resolution of a segmented gradient echo echo-planar imaging (EPI) technique as applied to proton resonance frequency (PRF) shift thermometry at 3 T in the human prostate gland, and to determine appropriate sequence parameters for magnetic resonance imaging (MRI)-controlled transurethral ultrasound thermal therapy.
  
  
  METHODS
  Eleven healthy volunteers (age range 23-58) were scanned at 3 T with a 16-channel torso coil to study the behavior of a gradient echo EPI thermometry sequence. The temperature stability and geometric distortion were assessed for 11 different parameter sets. In a further five volunteers, the prostate T2* was measured.
  
  
  RESULTS
  For all scan parameters investigated, the temperature standard deviation within the prostate was less than 1°C, while the distortion was less than 1 mm. Temperature stability was best with higher TE values (up to 25 msec), larger voxel sizes and lower EPI factors, but this had to be balanced against requirements for good spatial and temporal resolution. Prostate T2* values ranged from 30-50 msec.
  
  
  CONCLUSIONS
  A good balance between temperature stability and temporal/spatial resolution is obtained with TE = 15 msec, voxel size = 1.14 mm, and EPI factor = 9, resulting in a dynamic scan time of 7.2 seconds for the nine slices.
authors: Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.
authors: Elizabeth
authors: E
authors: Ramsay
authors: Charles
authors: C
authors: Mougenot
authors: Max
authors: M
authors: Köhler
authors: Michael
authors: M
authors: Bronskill
authors: Laurence
authors: L
authors: Klotz
authors: Masoom A
authors: MA
authors: Haider
authors: Rajiv
authors: R
authors: Chopra
mesh_terms: D000328:Adult; D001831:Body Temperature / Q000502:physiology*; D006801:Humans; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011467:Prostate / Q000033:anatomy & histology* / Q000502:physiology*; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013817:Thermography / Q000379:methods*; D014464:Ultrasonic Therapy / Q000379:methods*; D055815:Young Adult
keywords: MR thermometry; interventional MRI; proton resonance frequency shift; segmented EPI; thermal therapy