title: Diffusion-weighted magnetic resonance imaging for the evaluation of prostate cancer: optimal B value at 3T.
abstract: OBJECTIVE
  To retrospectively determine the optimal b value of diffusion-weighted imaging (DWI) for predicting the presence of localized prostate cancer, and to evaluate the utility of DWI under different b values in differentiating between cancers and benign prostatic tissues.
  
  
  METHODS
  Eighty patients with suspected prostate cancer underwent MRI including DWI at 3T, followed by radical prostatectomy. DWI was examined under different b values. Apparent diffusion coefficient (ADC) maps were generated by using b = 0, and other b values of 300, 700, 1000 or 2000 s/mm(2). For predicting the presence of cancers, four different ADC maps were analyzed independently by two blinded readers. ADCs were measured in benign and malignant tissues.
  
  
  RESULTS
  For predicting the presence of 110 prostate cancers, the sensitivity and area under the curve (AUC) for an experienced reader was significantly greater at b = 1000 (85% and 0.91) than b = 300, 700 or 2000 s/mm(2) (p < 0.01). For a less-experienced reader, the AUC was significantly greater at b = 700, 1000 or 2000 than b = 300 s/mm(2) (p < 0.01). Mean ADCs of the cancers in sequence from b = 300 to 2000 s/mm(2) were 1.33, 1.03, 0.88 and 0.68 × 10(-3) mm(2)/s, which were significantly lower than those of benign tissues (p < 0.001).
  
  
  CONCLUSIONS
  The optimal b value for 3T DWI for predicting the presence of prostate cancer may be 1000 s/mm(2).
authors: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Korea.
authors: Ji Hyun
authors: JH
authors: Koo
authors: Chan Kyo
authors: CK
authors: Kim
authors: Dongil
authors: D
authors: Choi
authors: Byung Kwan
authors: BK
authors: Park
authors: Ghee Young
authors: GY
authors: Kwon
authors: Bohyun
authors: B
authors: Kim
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D001706:Biopsy; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D017430:Prostate-Specific Antigen / Q000097:blood; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D017430:Prostate-Specific Antigen
keywords: Apparent diffusion coefficient; Diagnosis; Diffusion-weighted MR imaging; Prostate neoplasm