title: Normal central zone of the prostate and central zone involvement by prostate cancer: clinical and MR imaging implications.
abstract: OBJECTIVE
  To describe the anatomic features of the central zone of the prostate on T2-weighted and diffusion-weighted (DW) magnetic resonance (MR) images and evaluate the diagnostic performance of MR imaging in detection of central zone involvement by prostate cancer.
  
  
  METHODS
  The institutional review board waived informed consent and approved this retrospective, HIPAA-compliant study of 211 patients who underwent T2-weighted and DW MR imaging of the prostate before radical prostatectomy. Whole-mount step-section pathologic findings were the reference standard. Two radiologists independently recorded the visibility, MR signal intensity, size, and symmetry of the central zone and scored the likelihood of central zone involvement by cancer on T2-weighted MR images and on T2-weighted MR images plus apparent diffusion coefficient (ADC) maps generated from the DW MR images. Descriptive summary statistics were calculated for central zone imaging features. Sensitivity, specificity, and area under the curve were used to evaluate reader performance in detecting central zone involvement.
  
  
  RESULTS
  For readers 1 and 2, the central zone was visible, at least partially, in 177 (84%) and 170 (81%) of 211 patients, respectively. The most common imaging appearance of the central zone was symmetric, homogeneous low signal intensity. Cancers involving the central zone had higher prostate-specific antigen values, Gleason scores, and rates of extracapsular extension and seminal vesicle invasion compared with cancers not involving the central zone (P < .05). Area under the curve, sensitivity, and specificity in detecting central zone involvement were 0.70, 0.30, and 0.96 for reader 1 and 0.65, 0.35, and 0.93 for reader 2, and these values did not differ significantly between T2-weighted imaging and T2-weighted imaging plus ADC maps.
  
  
  CONCLUSIONS
  The central zone was visualized in most patients. Cancers involving the central zone were associated with more aggressive disease than those without central zone involvement.
authors.affiliation: Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, Room C-278, New York, NY 10065, USA. vargasah@mskcc.org
authors.forename: Hebert Alberto
authors.initials: HA
authors.lastname: Vargas
authors.forename: Oguz
authors.initials: O
authors.lastname: Akin
authors.forename: Tobias
authors.initials: T
authors.lastname: Franiel
authors.forename: Debra A
authors.initials: DA
authors.lastname: Goldman
authors.forename: Kazuma
authors.initials: K
authors.lastname: Udo
authors.forename: Karim A
authors.initials: KA
authors.lastname: Touijer
authors.forename: Victor E
authors.initials: VE
authors.lastname: Reuter
authors.forename: Hedvig
authors.initials: H
authors.lastname: Hricak
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011467:Prostate / Q000033:anatomy & histology*; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000601:surgery; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric