title: Diffusion-weighted magnetic resonance imaging in prostate cancer patients on active surveillance one year after diagnosis and before repeat biopsy.
abstract: OBJECTIVE
  The aim of this study was to evaluate prospectively whether diffusion-weighted magnetic resonance imaging (DW-MRI), interpreted in a routine clinical setting, can serve as a diagnostic and prognostic tool for prostate carcinoma patients on active surveillance (AS).
  
  
  METHODS
  Eighty men enrolled in the Finnish arm of the PRIAS (Prostate Cancer Research International: Active Surveillance) study were followed for at least 1 year and had DW-MRI scans taken in addition to repeat biopsy. Spearman's correlations were analysed between tumour appearance on DW-MRI and clinical variables [age, prostate-specific antigen (PSA), free PSA, PSA doubling time, prostate volume, percentage of cancer at diagnostic biopsy]. The Pearson chi-squared test clarified associations between outcome factors (number of positive cores and Gleason score on repeat biopsy, treatment change) and DW-MRI results. Assumed predictors of deferred radical treatment were examined with logistic regression analysis. Accuracy of tumour localization by DW-MRI compared to repeat biopsy findings was analysed by the chi-squared test.
  
  
  RESULTS
  DW-MRI revealed an anatomical lesion suggestive of cancer in 40 patients (50%). MRI positivity showed no significant correlation with clinical variables. No associations existed between tumour appearance on DW-MRI and biopsy findings or discontinuation of AS. The only variable predicting treatment change was higher PSA at discontinuation (p = 0.002). Appearance of tumour, either on T2-weighted MRI (p = 0.273) or on apparent diffusion coefficient maps (p = 0.691), was not a significant predictor of treatment change.
  
  
  CONCLUSIONS
  Localized low-grade prostate cancer is challenging to visualize in DW-MRI, and this imaging technique provides no additional prognostic benefit compared to PSA and repeat biopsies.
authors: Departments of Urology.
authors: Hanna
authors: H
authors: Vasarainen
authors: Kanerva
authors: K
authors: Lahdensuo
authors: Ritja
authors: R
authors: Savolainen
authors: Mirja
authors: M
authors: Ruutu
authors: Kimmo
authors: K
authors: Taari
authors: Antti
authors: A
authors: Rannikko
mesh_terms: D000368:Aged; D001706:Biopsy; D002277:Carcinoma / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy*; D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D011379:Prognosis; D011446:Prospective Studies; D011467:Prostate / Q000473:pathology*; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy*; D057832:Watchful Waiting
chemical_list: D017430:Prostate-Specific Antigen