title: Validating multiparametric MRI for diagnosis and monitoring of prostate cancer in patients for active surveillance.
abstract: OBJECTIVE
  To compare multiparametric magnetic resonance imaging (mpMRI) with transrectal ultrasound-guided prostate biopsy (TRUS-bx) for the diagnosis and monitoring of small-volume prostate cancer (PCa) in patients on active surveillance (AS).
  
  
  METHODS
  In a retrospective cross-sectional validation study, 100 patients on AS for PCa underwent a systematic 12-core TRUS-bx (the gold standard) as well as mpMRI, on either a 1.5 or 3 Tesla scanner (32 and 68 patients, respectively). Three pathologists reported biopsy histology separately. A single, experienced radiologist scored mpMRI scans using the PI-RADS system. We compared left- and right-sided PI-RADS scores of the peripheral zone with TRUS-bx results of the relevant prostate lobe. We then estimated the specificity and sensitivity of mpMRI in diagnosing low-grade low-risk PCa in our AS cohort.
  
  
  RESULTS
  The sensitivity of mpMRI was 37% (95% CI 28-47%) and specificity was 85% (CI 76-92%) for cancer. The negative predictive value was 51% (CI 44-60%), and the positive predictive value was 76% (CI 62-87%). The positive and negative likelihood ratios were 2.5 and 0.7, respectively.
  
  
  CONCLUSIONS
  Because of its low specificity and low negative predictive value, mpMRI is not suitable for diagnosing low-grade small-volume PCa. However, because of a specificity of 85% and a negative likelihood ratio of 0.7, mpMRI may be useful for follow-up of previously TRUS-bx diagnosed patients who are on AS.
authors.affiliation: Department of Urology, London North West Healthcare NHS Trust, Harrow, London, Middlesex, HA1 3UJ, UK.
authors.forename: Iqbal
authors.initials: I
authors.lastname: Sahibzada
authors.affiliation: Department of Urology, London North West Healthcare NHS Trust, Harrow, London, Middlesex, HA1 3UJ, UK. deepakbatura@gmail.com.
authors.forename: Deepak
authors.identifier: http://orcid.org/0000-0002-2833-1819
authors.initials: D
authors.lastname: Batura
authors.affiliation: Department of Urology, London North West Healthcare NHS Trust, Harrow, London, Middlesex, HA1 3UJ, UK.
authors.forename: Giles
authors.initials: G
authors.lastname: Hellawell
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D019160:Endosonography; D006801:Humans; D061705:Image-Guided Biopsy / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D011237:Predictive Value of Tests; D011467:Prostate / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000175:diagnosis*; D012372:ROC Curve; D012007:Rectum; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018426:SEER Program
keywords: Active surveillance; Biopsy; MRI; Prostate neoplasms; Sensitivity and specificity