title: Diffusion-weighted MRI of the prostate: advantages of Zoomed EPI with parallel-transmit-accelerated 2D-selective excitation imaging.
abstract: OBJECTIVE
  The purpose of our study was to evaluate the use of 2D-selective, parallel-transmit excitation magnetic resonance imaging (MRI) for diffusion-weighted echo-planar imaging (pTX-EPI) of the prostate, and to compare it to conventional, single-shot EPI (c-EPI).
  
  
  METHODS
  The MRI examinations of 35 patients were evaluated in this prospective study. PTX-EPI was performed with a TX-acceleration factor of 1.7 and a field of view (FOV) of 150 × 90 mm(2), whereas c-EPI used a full FOV of 380 × 297 mm(2). Two readers evaluated three different aspects of image quality on 5-point Likert scales. To quantify distortion artefacts, maximum diameters and prostate volume were determined for both techniques and compared to T2-weighted imaging.
  
  
  RESULTS
  The zoomed pTX-EPI was superior to c-EPI with respect to overall image quality (3.39 ± 0.62 vs 2.45 ± 0.67) and anatomic differentiability (3.29 ± 0.65 vs 2.41 ± 0.65), each with p < 0.0001. Artefacts were significantly less severe in pTX-EPI (0.93 ± 0.73 vs 1.49 ± 1.08), p < 0.001. The quantitative analysis yielded a higher agreement of pTX-EPI with T2-weighted imaging than c-EPI with respect to coronal (ICCs: 0.95 vs 0.93) and sagittal (0.86 vs 0.73) diameters as well as prostate volume (0.94 vs 0.92). Apparent diffusion coefficient (ADC) values did not differ significantly between the two techniques (p > 0.05).
  
  
  CONCLUSIONS
  Zoomed pTX-EPI leads to substantial improvements in diffusion-weighted imaging (DWI) of the prostate with respect to different aspects of image quality and severity of artefacts.
  
  
  CONCLUSIONS
  Recent technical developments in MRI allow the use of accelerated, spatially-selective excitation (parallel-transmit, pTX). pTX can be used for zoomed echo-planar prostate imaging (pTX-EPI). pTX-EPI improves different aspects of image quality in prostate MRI. Distortion artefacts are reduced by the use of pTX-EPI in prostate MRI. Further studies should aim at assessing the diagnostic accuracy of pTX-EPI.
authors.affiliation: Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich, Grosshadern Campus, Marchioninistr. 15, 81377, Munich, Germany, kolja.thierfelder@med.uni-muenchen.de.
authors.forename: Kolja M
authors.initials: KM
authors.lastname: Thierfelder
authors.forename: Michael K
authors.initials: MK
authors.lastname: Scherr
authors.forename: Mike
authors.initials: M
authors.lastname: Notohamiprodjo
authors.forename: Jakob
authors.initials: J
authors.lastname: Weiß
authors.forename: Olaf
authors.initials: O
authors.lastname: Dietrich
authors.forename: Ullrich G
authors.initials: UG
authors.lastname: Mueller-Lisse
authors.forename: Josef
authors.initials: J
authors.lastname: Pfeuffer
authors.forename: Konstantin
authors.initials: K
authors.lastname: Nikolaou
authors.forename: Daniel
authors.initials: D
authors.lastname: Theisen
mesh_terms: D000368:Aged; D016477:Artifacts; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011467:Prostate / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000175:diagnosis*; D015203:Reproducibility of Results