title: Apparent Diffusion Coefficient Values of the Benign Central Zone of the Prostate: Comparison With Low- and High-Grade Prostate Cancer.
abstract: OBJECTIVE
  The apparent diffusion coefficient (ADC) values for benign central zone (CZ) of the prostate were compared with ADC values of benign peripheral zone (PZ), benign transition zone (TZ), and prostate cancer, using histopathologic findings from radical prostatectomy as the reference standard.
  
  
  METHODS
  The study included 27 patients with prostate cancer (mean [± SD] age, 60.0 ± 7.6 years) who had 3-T endorectal coil MRI of the prostate performed before undergoing prostatectomy with whole-mount histopathologic assessment. Mean ADC values were recorded from the ROI within the index tumor and within benign CZ, PZ, and TZ, with the use of histopathologic findings as the reference standard. ADC values of the groups were compared using paired t tests and ROC curve analysis.
  
  
  RESULTS
  The ADC of benign CZ in the right (1138 ± 123 × 10(-6) mm(2)/s) and left (1166 ± 141 × 10(-6) mm(2)/s) lobes was not significantly different (p = 0.217). However, the ADC of benign CZ (1154 ± 129 × 10(-6) mm(2)/s) was significantly lower (p < 0.001) than the ADCs of benign PZ (1579 ± 197 × 10(-6) mm(2)/s) and benign TZ (1429 ± 180 × 10(-6) mm(2)/s). Although the ADC of index tumors (1042 ± 134 × 10(-6) mm(2)/s) was significantly lower (p = 0.002) than the ADC of benign CZ there was no significant difference (p = 0.225) between benign CZ and tumors with a Gleason score of 6 (1119 ± 87 × 10(-6) mm(2)/s). In 22.2% of patients (6/27), including five patients who had tumors with a Gleason score greater than 6, the ADC was lower in benign CZ than in the index tumor. The AUC of ADC for the differentiation of benign CZ from index tumors was 72.4% (sensitivity, 70.4%; specificity, 51.9%), and the AUC of ADC for differentiation from tumors with a Gleason score greater than 6 was 76.7% (sensitivity, 75.0%; specificity, 65.0%).
  
  
  CONCLUSIONS
  The ADC of benign CZ is lower than the ADC of other zones of the prostate and overlaps with the ADC of prostate cancer tissue, including high-grade tumors. Awareness of this potential diagnostic pitfall is important to avoid misinterpreting the normal CZ as suspicious for tumor.
authors.affiliation: 1 Department of Radiology, Duke University Medical Center, DUMC Box 3808, Durham, NC 27710.
authors.forename: Rajan T
authors.initials: RT
authors.lastname: Gupta
authors.affiliation: 1 Department of Radiology, Duke University Medical Center, DUMC Box 3808, Durham, NC 27710.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Kauffman
authors.affiliation: 1 Department of Radiology, Duke University Medical Center, DUMC Box 3808, Durham, NC 27710.
authors.forename: Kirema
authors.initials: K
authors.lastname: Garcia-Reyes
authors.affiliation: 2 Department of Biomedical Engineering, Duke University, Durham, NC.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Palmeri
authors.affiliation: 3 Department of Pathology, Duke University Medical School, Durham, NC.
authors.forename: John F
authors.initials: JF
authors.lastname: Madden
authors.affiliation: 4 Division of Urologic Surgery, Department of Surgery and Duke Prostate Center, Duke University Medical Center, Durham, NC.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Polascik
authors.affiliation: 5 Department of Radiology, New York University Langone Medical Center, New York, NY.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Rosenkrantz
mesh_terms: D000368:Aged; D001706:Biopsy; D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D011446:Prospective Studies; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000601:surgery
keywords: central zone; multiparametric prostate MRI; prostate cancer