title: Combined T2-weighted and diffusion-weighted MRI for localization of prostate cancer.
abstract: OBJECTIVE
  The objective of our study was to compare T2-weighted MRI alone and T2 combined with diffusion-weighted imaging (DWI) for the localization of prostate cancer.
  
  
  METHODS
  T2-weighted imaging and DWI (b value = 600 s/mm2) were performed in 49 patients before radical prostatectomy using an endorectal coil at 1.5 T in this prospective trial. The peripheral zone of the prostate was divided into sextants and the transition zone into left and right halves. T2 images alone and then T2 images combined with apparent diffusion coefficient (ADC) maps (T2 + DWI) were scored for the likelihood of tumor and were compared with whole-mount histology results. Fixed window and level settings were used to display the ADC maps. Only tumors with an area of more than 0.13 cm2 (> 4 mm diameter) and a Gleason score of > or = 6 were considered significant. The area under the receiver operating characteristic curve (A(z)) was used to assess accuracy.
  
  
  RESULTS
  In the peripheral zone, the A(z) value was significantly higher (p = 0.004) for T2 plus DWI (A(z) = 0.89) than for T2 imaging alone (A(z) = 0.81). Performance was poorer in the transition zone for both T2 plus DWI (A(z) = 0.78) and T2 (A(z) = 0.79). For the whole prostate, sensitivity was significantly higher (p < 0.001) with T2 plus DWI (81% [120/149]) than with T2 imaging alone (54% [81/149]), with T2 plus DWI showing only a slight loss in specificity compared with T2 imaging alone (84% [204/243] vs 91% [222/243], respectively).
  
  
  CONCLUSIONS
  Combined T2 and DWI MRI is better than T2 imaging alone in the detection of significant cancer (Gleason score > or = 6 and diameter > 4 mm) within the peripheral zone of the prostate.
authors.affiliation: Joint Department of Medical Imaging, Princess Margaret Hospital, University Health Network and Mount Sinai Hospital, University of Toronto, 610 University Ave., Toronto, ON M5G 2M9, Canada.
authors.forename: Masoom A
authors.initials: MA
authors.lastname: Haider
authors.forename: Theodorus H
authors.initials: TH
authors.lastname: van der Kwast
authors.forename: Jeff
authors.initials: J
authors.lastname: Tanguay
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Evans
authors.forename: Ali-Tahir
authors.initials: AT
authors.lastname: Hashmi
authors.forename: Gina
authors.initials: G
authors.lastname: Lockwood
authors.forename: John
authors.initials: J
authors.lastname: Trachtenberg
mesh_terms: D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000473:pathology*; D012372:ROC Curve