title: Evaluation of diffusion-weighted MR imaging at inclusion in an active surveillance protocol for low-risk prostate cancer.
abstract: OBJECTIVE
  We aimed to determine whether diffusion-weighted magnetic resonance imaging, by means of the apparent diffusion coefficient (ADC), is able to guide magnetic resonance-guided biopsy in patients fit for active surveillance (AS) and identify patients harboring high-grade Gleason components not suitable for AS.
  
  
  METHODS
  Our study was approved by the institutional review board of all participating hospitals, and all patients signed informed consent at inclusion. Fifty-four consecutive patients with low-risk prostate cancer (PCa) underwent multiparametric magnetic resonance imaging (MP-MRI) at inclusion for AS. Cancer-suspicious regions (CSRs) upon 3-T MP-MRI were identified in all patients, and magnetic resonance-guided biopsy was performed in all CSRs to obtain histopathological verification. For all CSRs, a median ADC (mADC) was calculated. Wilcoxon signed ranks and Mann-Whitney tests was performed to detect differences between the groups. We used the area under the receiver operating characteristic curve to evaluate the accuracy of mADC to predict the presence of PCa in a CSR. Level of statistical significance was set at P < 0.05.
  
  
  RESULTS
  Mean mADC in the CSRs with PCa was 1.04 × 10⁻³ mm²/s (SD, 0.29), whereas the CSRs with no PCa displayed a mean mADC of 1.26 × 10⁻³ mm²/s (SD, 0.25; P < 0.001). Cancer-suspicious regions with a high-grade Gleason component displayed a mean mADC of 0.84 × 10⁻³ mm²/s (SD, 0.35) vs a mean mADC for the low-grade CSRs of 1.09 × 10⁻³ mm²/s (SD, 0.25; P < 0.05). A diagnostic accuracy of mADC for predicting the presence of PCa in a CSR with an area under the receiver operating characteristic curve of 0.73 was established (95% confidence interval, 0.61-0.84).
  
  
  CONCLUSIONS
  Median ADC is able to predict the presence and grade of PCa in CSRs identified by MP-MRI.
authors: Department of Urology, Canisius-Wilhelmina Hospital, Radboud University Nijmegen Medical Center, The Netherlands. r.somford@cwz.nl
authors: Diederik M
authors: DM
authors: Somford
authors: Caroline M
authors: CM
authors: Hoeks
authors: Christina A
authors: CA
authors: Hulsbergen-van de Kaa
authors: Thomas
authors: T
authors: Hambrock
authors: Jurgen J
authors: JJ
authors: Fütterer
authors: J Alfred
authors: JA
authors: Witjes
authors: Chris H
authors: CH
authors: Bangma
authors: Henk
authors: H
authors: Vergunst
authors: Geert A
authors: GA
authors: Smits
authors: Jorg R
authors: JR
authors: Oddens
authors: Inge M
authors: IM
authors: van Oort
authors: Jelle O
authors: JO
authors: Barentsz
mesh_terms: D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000473:pathology*; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity