title: Endorectal magnetic resonance imaging and spectroscopy for the detection of tumor foci in men with prior negative transrectal ultrasound prostate biopsy.
abstract: OBJECTIVE
  We determined the ability of combined endorectal magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) to detect prostate cancer foci prospectively in men with prior negative transrectal ultrasound (TRUS) prostate biopsy.
  
  
  METHODS
  Endorectal MRI with spectroscopy was performed in 24 consecutive patients with 1 or more prior negative TRUS prostatic biopsies for persistently increased prostate specific antigen and/or abnormal digital rectal examination. All studies were interpreted by a dedicated radiologist who reported areas of interest in the peripheral zone as normal, equivocal or suspicious on MRI and MRSI separately. Equivocal and suspicious areas were then correlated with a 3-dimensional prostate model. All patients underwent a standard TRUS 10-core peripheral zone biopsy with up to 4 additional biopsies targeted at the equivocal or suspected sites.
  
  
  RESULTS
  Prostate cancer was detected in 7 of 24 subjects (29.2%). Considering the equivocal category as test negative the sensitivity, specificity, positive and negative predictive values, and the accuracy of MRI, MRSI and combined MRI/MRSI for the detection of prostate cancer were 57.1%, 57.1% and 100.0%, 88.2%, 82.4% and 70.6%, 66.7%, 57.1% and 58.3%, 83.3%, 82.1% and 100%, and 79.2%, 75.0% and 79.2%, respectively. The site of positive biopsy correlated correctly in 50% and 28.6% of MRI and MRSI labeled suspicious cores, respectively.
  
  
  CONCLUSIONS
  MRI and MRSI have the potential to identify cancer foci and direct TRUS in patients with a previous negative TRUS biopsy. Further, larger studies are required to quantify the amount of benefit.
authors.affiliation: Department of Urology, Singapore General Hospital, Singapore. gurysp@sgh.com.sg
authors.forename: J S P
authors.initials: JS
authors.lastname: Yuen
authors.forename: C H
authors.initials: CH
authors.lastname: Thng
authors.forename: P H
authors.initials: PH
authors.lastname: Tan
authors.forename: L W
authors.initials: LW
authors.lastname: Khin
authors.forename: S J L
authors.initials: SJ
authors.lastname: Phee
authors.forename: D
authors.initials: D
authors.lastname: Xiao
authors.forename: W K O
authors.initials: WK
authors.lastname: Lau
authors.forename: W S
authors.initials: WS
authors.lastname: Ng
authors.forename: C W S
authors.initials: CW
authors.lastname: Cheng
mesh_terms: D000368:Aged; D000465:Algorithms; D001707:Biopsy, Needle / Q000379:methods*; D005189:False Positive Reactions; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D012007:Rectum; D014463:Ultrasonography