title: Prostate cancer: comparison of tumor visibility on trace diffusion-weighted images and the apparent diffusion coefficient map.
abstract: OBJECTIVE
  The purpose of our study was to compare the visibility of prostate cancer on trace diffusion-weighted (DW) images and the apparent diffusion coefficient (ADC) map.
  
  
  METHODS
  In this retrospective study, 45 patients with prostate cancer underwent preoperative MRI, including DW imaging (DWI) (b values 0, 500, and 1,000 s/mm(2)). A single observer reviewed the images in conjunction with tumor maps constructed from prostatectomy. For 132 peripheral zone (PZ) tumor foci, the visibility and contrast relative to benign PZ were recorded for T2-weighted imaging, trace DWI b500 images, trace DWI b1,000 images, and ADC maps. Trace DWI b1,000 images and ADC maps were compared in terms of Gleason score, size, normalized T2 signal intensity, ADC, and normalized ADC of visible tumors.
  
  
  RESULTS
  For each image set, the percentage of visible tumor foci and contrast relative to benign PZ were as follows: T2-weighted imaging, 80.3% and 0.411; trace DWI b500, 26.5% and 0.131; trace DWI b1,000, 46.2% and 0.119; and ADC maps, 62.1% and 0.309. Forty-seven tumor foci were visible on both trace DWI b1,000 images and ADC maps, 14 only on trace DWI b1,000 images, 35 only on ADC maps, and 36 on neither image set. There was no significant difference in Gleason score, size, normalized T2 signal intensity, ADC, or normalized ADC between tumors visible only on trace DWI b1,000 images and those visible only on ADC maps.
  
  
  CONCLUSIONS
  Given a greater proportion of tumors visible on the ADC map than trace DWI and greater contrast relative to benign PZ on the ADC map, we suggest that, when performing DWI of the prostate, careful attention be given to the ADC map for tumor identification.
authors.affiliation: Department of Radiology, New York University Langone Medical Center, 560 First Ave., TCH-HW202, New York, NY 10016, USA. andrew.rosenkrantz@nyumc.org
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Rosenkrantz
authors.forename: Xiangtian
authors.initials: X
authors.lastname: Kong
authors.forename: Benjamin E
authors.initials: BE
authors.lastname: Niver
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Berkman
authors.forename: Jonathan
authors.initials: J
authors.lastname: Melamed
authors.forename: James S
authors.initials: JS
authors.lastname: Babb
authors.forename: Samir S
authors.initials: SS
authors.lastname: Taneja
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001706:Biopsy; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D012189:Retrospective Studies