title: Per-sextant localization and staging of prostate cancer: correlation of imaging findings with whole-mount step section histopathology.
abstract: OBJECTIVE
  The objective of our study was to determine the diagnostic accuracy and interobserver agreement of 1.5-T prostatic MRI for per-sextant tumor localization and staging of prostate cancer as compared with whole-mount step section histopathology.
  
  
  METHODS
  Combined endorectal-pelvic phased-array prostatic MRI scans obtained at 1.5 T of 106 patients with biopsy-proven prostate cancer who had undergone radical prostatectomy with whole-mount step section histopathology within 28 days of MRI were retrospectively analyzed by three independent abdominal radiologists (reviewers 1, 2, and 3). Sextants of the prostate (right and left base, middle, and apex) were evaluated for the presence of prostate cancer and extracapsular extension (ECE) using a 5-point confidence scale. Data were statistically analyzed using receiver operating characteristic (ROC) analysis. Interobserver variability was assessed by kappa statistics. For calculation of sensitivity and specificity, data from the 5-point confidence scale were dichotomized into negative (score of 1-3) or positive (score of 4 or 5) findings.
  
  
  RESULTS
  Forty-one patients had ECE (tumor stage T3), and 65 patients had organ-confined disease (stage T2). Of 636 prostatic sextants, 417 were positive for prostate cancer and 135 were positive for ECE at histopathology. For prostate cancer localization, ROC analysis yielded area under the ROC curve (AUC) values ranging from 0.776 +/- 0.023 (SD) to 0.832 +/- 0.027. For the detection of ECE, the AUC values ranged from 0.740 +/- 0.054 to 0.812 +/- 0.045. Interobserver agreement (kappa) ranged from 0.49 to 0.60 for prostate cancer localization and from 0.59 to 0.67 for the detection of ECE.
  
  
  CONCLUSIONS
  Using the sextant framework, independent observers reach similar accuracy with moderate to substantial agreement for the localization of prostate cancer and ECE by means of MRI of the prostate.
authors.affiliation: Department of Clinical Radiology, University of Munich, Marchioninistrasse 15, Munich 81377, Germany.
authors.forename: Anno
authors.initials: A
authors.lastname: Graser
authors.forename: Andreas
authors.initials: A
authors.lastname: Heuck
authors.forename: Bernhard
authors.initials: B
authors.lastname: Sommer
authors.forename: Joerg
authors.initials: J
authors.lastname: Massmann
authors.forename: Juergen
authors.initials: J
authors.lastname: Scheidler
authors.forename: Maximillian
authors.initials: M
authors.lastname: Reiser
authors.forename: Ullrich
authors.initials: U
authors.lastname: Mueller-Lisse
mesh_terms: D019412:Anatomy, Cross-Sectional / Q000379:methods*; D044963:Biopsy, Fine-Needle; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D015588:Observer Variation; D011471:Prostatic Neoplasms / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity