title: Zoomed echo-planar imaging using parallel transmission: impact on image quality of diffusion-weighted imaging of the prostate at 3T.
abstract: OBJECTIVE
  To assess impact of two-channel parallel transmission (pTx) with focused excitation [zoomed echo-planar imaging (EPI)] on image quality of prostate diffusion-weighted imaging (DWI) at 3T.
  
  
  METHODS
  27 male volunteers (27 ± 8 years) underwent 3T prostate MRI using 2-channel radiofrequency-transmit system and 18-channel torso receive coil. Scans included EPI-DWI sequence (b values 50, 500, 1000 s/mm(2)) acquired both with standard sinc pulse and 2-channel pTX with focused excitation, each acquired at large-field-of-view (FOV) (20 × 20 cm) and small-FOV (14 × 14 cm). An abdominal radiologist scored b-1000 images and ADC maps for image quality measures. Sequences were compared using paired Wilcoxon tests.
  
  
  RESULTS
  pTx with focused excitation showed significant improvements compared with standard DWI on b-1000 images at large-FOV for the absence of wrap and overall image quality (p ≤ 0.049); on b-1000 images at small-FOV for reduced distortion of prostate, absence of ghosting, absence of wrap, clarity of prostate capsule, clarity of peripheral/transition zone boundary, clarity of peri-urethral region, and overall image quality (p ≤ 0.004); and on ADC maps at small-FOV for reduced distortion of prostate, sharpness of prostate, clarity of prostatic capsule, clarity of peri-urethral region, and overall image quality (p = 0.002-0.036). When compared with standard large-FOV images, small-FOV images obtained using pTx with focused excitation showed no significant difference on the b-1000 images for any feature (p ≥ 0.175), while showing significant improvements on the ADC maps in terms of reduced distortion, absence of ghosting, and absence of wrap (p = 0.010-0.030).
  
  
  CONCLUSIONS
  Zoomed DWI using 2-channel pTx reduced artifacts and improved image quality for 3T prostate DWI; benefit was most apparent for small-FOV images.
authors: Department of Radiology, NYU Langone Medical Center, 550 First Avenue, New York, NY, 10016, USA, andrew.rosenkrantz@nyumc.org.
authors: Andrew B
authors: AB
authors: Rosenkrantz
authors: Hersh
authors: H
authors: Chandarana
authors: Josef
authors: J
authors: Pfeuffer
authors: Michael J
authors: MJ
authors: Triolo
authors: Mohammed Bilal
authors: MB
authors: Shaikh
authors: David J
authors: DJ
authors: Mossa
authors: Christian
authors: C
authors: Geppert
mesh_terms: D000328:Adult; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011467:Prostate / Q000033:anatomy & histology*; D012016:Reference Values; D015203:Reproducibility of Results; D055815:Young Adult