title: High and ultra-high b-value diffusion-weighted imaging in prostate cancer: a quantitative analysis.
abstract: BACKGROUND
  Diffusion-weighted imaging (DWI) is routinely used in magnetic resonance imaging (MRI) of prostate cancer. However, the routine use of b values higher than 1000 s/mm(2) is not clear up to present. Moreover, the complex diffusion behavior of malignant and benign prostate tissues hampers precise predictions of contrast in DWI images and apparent diffusion coefficient (ADC) maps.
  
  
  OBJECTIVE
  To quantitatively analyze DWI with different b values in prostate cancer and to identify b values best suitable for cancer detection.
  
  
  METHODS
  Forty-one patients with histologically proven prostate cancer were examined with high resolution T2-weighted imaging and DWI at 3 Tesla. Five different b values (0, 800, 1000, 1500, 2000 s/mm(2)) were applied. ADC values of tumors and reference areas were measured on ADC maps derived from different pairs of b values. Furthermore, signal intensities of DW images of tumors and reference areas were measured. For analysis, contrast ratios of ADC values and signal intensities of DW images were calculated and compared.
  
  
  RESULTS
  No significant differences were found between contrast ratios measured on ADC maps of all analyzed b value pairs (P = 0.43). Contrast ratios calculated from signal intensities of DW images were highest at b values of 1500 and 2000 s/mm(2) and differed significantly from contrast ratios at b values of 800 and 1000 s/mm(2) (P < 0.01).
  
  
  CONCLUSIONS
  Whereas contrast in ADC maps does not significantly change with different b values, contrast ratios of DW images are significantly higher at b-values of 1500 and 2000 s/mm(2) in comparison to b values of 800 and 1000 s/mm(2). Therefore, diagnostic performance of DWI in prostate cancer might be increased by application of b values higher than 1000 s/mm(2).
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany axel.wetter@uk-essen.de.
authors.forename: Axel
authors.initials: A
authors.lastname: Wetter
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Nensa
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Lipponer
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany.
authors.forename: Nika
authors.initials: N
authors.lastname: Guberina
authors.affiliation: Department of Urology and Paediatric Urology, University Hospital Essen, Essen, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Olbricht
authors.affiliation: Department of Urology and Paediatric Urology, University Hospital Essen, Essen, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Schenck
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Schlosser
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany.
authors.forename: Marcel
authors.initials: M
authors.lastname: Gratz
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Lauenstein
mesh_terms: D000368:Aged; D000465:Algorithms; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D011471:Prostatic Neoplasms / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: ADC; Prostate cancer; diffusion-weighted magnetic resonance imaging