title: High b value (2,000 s/mm2) diffusion-weighted magnetic resonance imaging in prostate cancer at 3 Tesla: comparison with 1,000 s/mm2 for tumor conspicuity and discrimination of aggressiveness.
abstract: OBJECTIVE
  The objective of our study was to investigate tumor conspicuity and the discrimination potential for tumor aggressiveness on diffusion-weighted magnetic resonance imaging (DW-MRI) with high b value at 3-T.
  
  
  METHODS
  The institutional review board approved this study and waived the requirement for informed consent. A total of 50 patients with prostate cancer (69 cancer foci; 48 in the PZ, 20 in the TZ, and one in whole prostate) who underwent multiparametric prostate MRI including DW-MRI (b values: 0, 1000 s/mm2 and 0, 2000 s/mm2) on a 3-T system were included. Lesion conspicuity score (LCS) using visual assessment (1 = invisible for surrounding normal site; 2 = slightly high intensity; 3 = moderately high; and 4 = very high) and tumor-normal signal intensity ratio (TNR) were assessed, and apparent diffusion coefficient (ADC, ×10-3 mm2/s) of the tumor regions and normal regions were measured.
  
  
  RESULTS
  Mean LCS and TNR at 0, 2000 s/mm2 was significantly higher than those at 0, 1000 s/mm2 (p<0.001 for both). In addition, ADC at both 0, 1000 and 0, 2000 s/mm2 was found to distinguish intermediate or high risk cancer with Gleason score ≥7 from low risk cancer with Gleason score ≤6 (p<0.001 for both). Furthermore, ADC of tumor regions correlated with Gleason score at both 0, 1000 s/mm2 (ρ = -0.602; p<0.001) and 0, 2000 s/mm2 (ρ = -0.645; p<0.001).
  
  
  CONCLUSIONS
  For tumor conspicuity and characterization of prostate cancer on DW-MRI of 3-T MRI, b = 0, 2000 s/mm2 is more useful than b = 0, 1000 s/mm2.
authors.affiliation: Department of Radiology, Kawasaki Medical School, Kurashiki city, Okayama, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Tamada
authors.affiliation: Department of Pathology, Kawasaki Medical School, Kurashiki city, Okayama, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Kanomata
authors.affiliation: Department of Radiology, Kawasaki Medical School, Kurashiki city, Okayama, Japan.
authors.forename: Teruki
authors.initials: T
authors.lastname: Sone
authors.affiliation: Department of Urology, Kawasaki Medical School, Kurashiki city, Okayama, Japan.
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Jo
authors.affiliation: Department of Urology, Kawasaki Medical School, Kurashiki city, Okayama, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Miyaji
authors.affiliation: Department of Radiology, Kawasaki Medical School, Kurashiki city, Okayama, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Higashi
authors.affiliation: Department of Radiology, Kawasaki Medical School, Kurashiki city, Okayama, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Yamamoto
authors.affiliation: Department of Radiology, Kawasaki Medical School, Kurashiki city, Okayama, Japan.
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Ito
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading / Q000379:methods; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D012189:Retrospective Studies