title: Defining the learning curve for multiparametric magnetic resonance imaging (MRI) of the prostate using MRI-transrectal ultrasonography (TRUS) fusion-guided transperineal prostate biopsies as a validation tool.
abstract: OBJECTIVE
  To determine the accuracy of multiparametric magnetic resonance imaging (mpMRI) during the learning curve of radiologists using MRI targeted, transrectal ultrasonography (TRUS) guided transperineal fusion biopsy (MTTP) for validation.
  
  
  METHODS
  Prospective data on 340 men who underwent mpMRI (T2-weighted and diffusion-weighted MRI) followed by MTTP prostate biopsy, was collected according to Ginsburg Study Group and Standards for Reporting of Diagnostic Accuracy standards. MRI data were reported by two experienced radiologists and scored on a Likert scale. Biopsies were performed by consultant urologists not 'blinded' to the MRI result and men had both targeted and systematic sector biopsies, which were reviewed by a dedicated uropathologist. The cohorts were divided into groups representing five consecutive time intervals in the study. Sensitivity and specificity of positive MRI reports, prostate cancer detection by positive MRI, distribution of significant Gleason score and negative MRI with false negative for prostate cancer were calculated. Data were sequentially analysed and the learning curve was determined by comparing the first and last group.
  
  
  RESULTS
  We detected a positive mpMRI in 64 patients from Group A (91%) and 52 patients from Group E (74%). The prostate cancer detection rate on mpMRI increased from 42% (27/64) in Group A to 81% (42/52) in Group E (P < 0.001). The prostate cancer detection rate by targeted biopsy increased from 27% (17/64) in Group A to 63% (33/52) in Group E (P < 0.001). The negative predictive value of MRI for significant cancer (>Gleason 3+3) was 88.9% in Group E compared with 66.6% in Group A.
  
  
  CONCLUSIONS
  We demonstrate an improvement in detection of prostate cancer for MRI reporting over time, suggesting a learning curve for the technique. With an improved negative predictive value for significant cancer, decision for biopsy should be based on patient/surgeon factors and risk attributes alongside the MRI findings.
authors.affiliation: Department of Urology, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Gabriele
authors.identifier: http://orcid.org/0000-0002-7013-7833
authors.initials: G
authors.lastname: Gaziev
authors.affiliation: Department of Urology, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Karan
authors.initials: K
authors.lastname: Wadhwa
authors.affiliation: Department of Radiology, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Tristan
authors.initials: T
authors.lastname: Barrett
authors.affiliation: Department of Radiology, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Brendan C
authors.initials: BC
authors.lastname: Koo
authors.affiliation: Department of Radiology, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Ferdia A
authors.initials: FA
authors.lastname: Gallagher
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, UK.|Cancer Research UK, Cambridge Research Institute, Cambridge, UK.
authors.forename: Eva
authors.initials: E
authors.lastname: Serrao
authors.affiliation: Department of Urology, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Julia
authors.initials: J
authors.lastname: Frey
authors.affiliation: Department of Urology, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Jonas
authors.initials: J
authors.lastname: Seidenader
authors.affiliation: Department of Urology, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Lina
authors.initials: L
authors.lastname: Carmona
authors.affiliation: Department of Histopathology, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Anne
authors.initials: A
authors.lastname: Warren
authors.affiliation: Translational Prostate Cancer Group, Department of Oncology, University of Cambridge, Cambridge, UK.
authors.forename: Vincent
authors.initials: V
authors.lastname: Gnanapragasam
authors.affiliation: Department of Urology, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Doble
authors.affiliation: Department of Urology, Addenbrooke's Hospital, Cambridge, UK.
authors.forename: Christof
authors.initials: C
authors.lastname: Kastner
mesh_terms: D000368:Aged; D006801:Humans; D061705:Image-Guided Biopsy / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011467:Prostate / Q000000981:diagnostic imaging* / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D014463:Ultrasonography
keywords: diagnosis; image-guided biopsy; learning curve; magnetic resonance imaging (MRI); prostatic neoplasm