title: Performance characteristics of MR imaging in the evaluation of clinically low-risk prostate cancer: a prospective study.
abstract: OBJECTIVE
  To prospectively evaluate diagnostic performance of T2-weighted magnetic resonance (MR) imaging and MR spectroscopic imaging in detecting lesions stratified by pathologic volume and Gleason score in men with clinically determined low-risk prostate cancer.
  
  
  METHODS
  The institutional review board approved this prospective, HIPAA-compliant study. Written informed consent was obtained from 183 men with clinically low-risk prostate cancer (cT1-cT2a, Gleason score≤6 at biopsy, prostate-specific antigen [PSA] level<10 ng/mL [10 μg/L]) undergoing MR imaging before prostatectomy. By using a scale of 1-5 (score 1, definitely no tumor; score 5, definitely tumor), two radiologists independently scored likelihood of tumor per sextant on T2-weighted images. Two spectroscopists jointly recorded locations of lesions with metabolic features consistent with tumor on MR spectroscopic images. Whole-mount step-section histopathologic analysis constituted the reference standard. Diagnostic performance at sextant level (T2-weighted imaging) and detection sensitivities (T2-weighted imaging and MR spectroscopic imaging) for lesions of 0.5 cm3 or larger were calculated.
  
  
  RESULTS
  For T2-weighted imaging, areas under the receiver operating characteristic curves for sextant-level detection were 0.77 (reader 1) and 0.82 (reader 2). For lesions of ≥0.5 cm3 and, 1<cm3, sensitivities were significantly lower when the lesion Gleason score was ≤6 (0.44 [reader 1] and 0.61 [reader 2]) rather than when the Gleason score was ≥7 (0.73, P=.02 [reader 1]; and 0.84, P=.05 [reader 2]). For lesions of ≥1 cm3, lesion Gleason score did not significantly affect sensitivity (0.83 [reader 1] and 1.00 [reader 2] for Gleason score≤6 vs 0.82 and 0.92 for Gleason score≥7; P≥.07). MR spectroscopic imaging sensitivity was low and was not significantly affected by pathologic lesion volume or Gleason score.
  
  
  CONCLUSIONS
  In men with clinically low-risk prostate cancer, detection of lesions of <1 cm3 with T2-weighted imaging is significantly dependent on lesion Gleason score; detection of lesions of ≥1 cm3 is significantly better than detection of smaller lesions and is not affected by lesion Gleason score. The role of MR spectroscopic imaging alone in this population is limited.
authors.affiliation: Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, Room C-278, New York, NY 10065, USA.
authors.forename: Hebert Alberto
authors.initials: HA
authors.lastname: Vargas
authors.forename: Oguz
authors.initials: O
authors.lastname: Akin
authors.forename: Amita
authors.initials: A
authors.lastname: Shukla-Dave
authors.forename: Jingbo
authors.initials: J
authors.lastname: Zhang
authors.forename: Kristen L
authors.initials: KL
authors.lastname: Zakian
authors.forename: Junting
authors.initials: J
authors.lastname: Zheng
authors.forename: Kent
authors.initials: K
authors.lastname: Kanao
authors.forename: Debra A
authors.initials: DA
authors.lastname: Goldman
authors.forename: Chaya S
authors.initials: CS
authors.lastname: Moskowitz
authors.forename: Victor E
authors.initials: VE
authors.lastname: Reuter
authors.forename: James A
authors.initials: JA
authors.lastname: Eastham
authors.forename: Peter T
authors.initials: PT
authors.lastname: Scardino
authors.forename: Hedvig
authors.initials: H
authors.lastname: Hricak
mesh_terms: D000328:Adult; D000368:Aged; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care / Q000379:methods; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000473:pathology*; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity