title: Prostate cancer: apparent diffusion coefficient map with T2-weighted images for detection--a multireader study.
abstract: OBJECTIVE
  To retrospectively assess the incremental value of an apparent diffusion coefficient (ADC) map combined with T2-weighted magnetic resonance (MR) images compared with T2-weighted images alone for prostate cancer detection by using a pathologic map as the reference standard.
  
  
  METHODS
  This retrospective study was approved by the institutional review board; informed consent was waived. The study included 52 patients (mean age, 65 years +/- 5 [standard deviation]; range, 48-76 years) who underwent endorectal MR imaging and step-section histologic examination. Three readers with varying experience levels reviewed T2-weighted images alone, the ADC map alone, and T2-weighted images and ADC maps. The prostate was divided into 12 segments. The probability of prostate cancer in each segment on MR images was recorded with a five-point scale. Areas under the receiver operating characteristic curve (AUCs) were compared by using the Z test; sensitivity and specificity were determined with the Z test after adjusting for data clustering.
  
  
  RESULTS
  AUC of T2-weighted and ADC data (reader 1, 0.90; reader 2, 0.88; reader 3, 0.76) was greater than that of T2-weighted images (reader 1, 0.79; reader 2, 0.75; reader 3, 0.66) for all readers (P < .0001 in all comparisons). AUC of T2-weighted and ADC data was greater for readers 1 and 2 than for reader 3 (P < .001). Sensitivity of T2-weighted and ADC data (reader 1, 88%; reader 2, 81%; and reader 3, 78%) was greater than that of T2-weighted images (reader 1, 74%; reader 2, 67%; reader 3, 67%) for all readers (P = .01 for reader 1; P = .02 for readers 2 and 3). Specificity of T2-weighted and ADC data was greater than that of T2-weighted images for reader 1 (88% vs 79%, P = .03) and reader 2 (89% vs 77%, P < .001).
  
  
  CONCLUSIONS
  The addition of an ADC map to T2-weighted images can improve the diagnostic performance of MR imaging in prostate cancer detection.
authors.affiliation: Department of Radiology, Asan Medical Center, University of Ulsan, 388-1 Poongnap-dong, Songpa-gu, Seoul, 138-736, South Korea.
authors.forename: Hyun Kyung
authors.initials: HK
authors.lastname: Lim
authors.forename: Jeong Kon
authors.initials: JK
authors.lastname: Kim
authors.forename: Kyung Ah
authors.initials: KA
authors.lastname: Kim
authors.forename: Kyoung-Sik
authors.initials: KS
authors.lastname: Cho
mesh_terms: D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000295:instrumentation*; D004867:Equipment Design; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011467:Prostate / Q000473:pathology*; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity