title: Multiparametric MR imaging for detection of clinically significant prostate cancer: a validation cohort study with transperineal template prostate mapping as the reference standard.
abstract: OBJECTIVE
  To evaluate the diagnostic performance of multiparametric (MP) magnetic resonance (MR) imaging for prostate cancer detection by using transperineal template prostate mapping (TTPM) biopsies as the reference standard and to determine the potential ability of MP MR imaging to identify clinically significant prostate cancer.
  
  
  METHODS
  Institutional review board exemption was granted by the local research ethics committee for this retrospective study. Included were 64 men (mean age, 62 years [range, 40-76]; mean prostate-specific antigen, 8.2 ng/mL [8.2 μg/L] [range, 2.1-43 ng/mL]), 51 with biopsy-proved cancer and 13 suspected of having clinically significant cancer that was biopsy negative or without prior biopsy. MP MR imaging included T2-weighted, dynamic contrast-enhanced and diffusion-weighted imaging (1.5 T, pelvic phased-array coil). Three radiologists independently reviewed images and were blinded to results of biopsy. Two-by-two tables were derived by using sectors of analysis of four quadrants, two lobes, and one whole prostate. Primary target definition for clinically significant disease necessary to be present within a sector of analysis on TTPM for that sector to be deemed positive was set at Gleason score of 3+4 or more and/or cancer core length involvement of 4 mm or more. Sensitivity, negative predictive value, and negative likelihood ratio were calculated to determine ability of MP MR imaging to rule out cancer. Specificity, positive predictive value, positive likelihood ratio, accuracy (overall fraction correct), and area under receiver operating characteristic curves were also calculated.
  
  
  RESULTS
  Twenty-eight percent (71 of 256) of sectors had clinically significant cancer by primary endpoint definition. For primary endpoint definition (≥ 4 mm and/or Gleason score ≥ 3+4), sensitivity, negative predictive value, and negative likelihood ratios were 58%-73%, 84%-89%, and 0.3-0.5, respectively. Specificity, positive predictive value, and positive likelihood ratios were 71%-84%, 49%-63%, and 2.-3.44, respectively. Area under the curve values were 0.73-0.84.
  
  
  CONCLUSIONS
  Results of this study indicate that MP MR imaging has a high negative predictive value to rule out clinically significant prostate cancer and may potentially have clinical use in diagnostic pathways of men at risk.
authors.affiliation: Division of Surgery and Interventional Sciences, University College, Charles Bell House, 67-73 Riding House St, London W1W 7EJ, England.
authors.forename: Nimalan
authors.initials: N
authors.lastname: Arumainayagam
authors.forename: Hashim U
authors.initials: HU
authors.lastname: Ahmed
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Moore
authors.forename: Alex
authors.initials: A
authors.lastname: Freeman
authors.forename: Clare
authors.initials: C
authors.lastname: Allen
authors.forename: S Aslam
authors.initials: SA
authors.lastname: Sohaib
authors.forename: Alex
authors.initials: A
authors.lastname: Kirkham
authors.forename: Jan
authors.initials: J
authors.lastname: van der Meulen
authors.forename: Mark
authors.initials: M
authors.lastname: Emberton
mesh_terms: D000368:Aged; D015331:Cohort Studies; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards*; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000473:pathology*; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique / Q000706:statistics & numerical data*; D006113:United Kingdom