title: Usefulness of diffusion-weighted imaging in the localization of prostate cancer.
abstract: OBJECTIVE
  Advances in high-precision radiation therapy techniques for patients with prostate cancer permit selective escalation of the radiation dose delivered to the dominant intraprostatic lesion and improve the therapeutic ratio. We evaluated the value of diffusion-weighted imaging (DWI) for dominant intraprostatic lesion assessment.
  
  
  METHODS
  The study population consisted of 23 patients with early prostate cancer. Before undergoing total prostatectomy, they were evaluated by means of magnetic resonance imaging, including DWI. T2-weighted imaging (T2WI) with and without DWI were retrospectively assessed by six independent observers. Imaging findings were compared with pathologic results from whole prostate specimens on a lesion-by-lesion basis.
  
  
  RESULTS
  Pathologic study identified 43 lesions in 23 patients. On magnetic resonance imaging, the six observers correctly identified 11-22 of 43 lesions (sensitivity, 26-51%) on T2WI alone and 20-31 (sensitivity, 47-72%) on T2WI plus DWI. Positive predictive values were 42-73% on T2WI alone and 58-80% on T2WI plus DWI. For all observers, detection was higher on combined T2WI and DWI than on T2WI alone.
  
  
  CONCLUSIONS
  Because the addition of DWI to T2WI improves the detectability of prostate cancer, DWI may offer a promising new approach for radiation therapy planning.
authors.affiliation: Department of Radiology, Kumamoto Chuo Hospital, Japan.
authors.forename: Hiroo
authors.initials: H
authors.lastname: Kajihara
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Hayashida
authors.forename: Ryuji
authors.initials: R
authors.lastname: Murakami
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Katahira
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Nishimura
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Hamada
authors.forename: Kousuke
authors.initials: K
authors.lastname: Kitani
authors.forename: Mitsuhiko
authors.initials: M
authors.lastname: Kitaoka
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Mika
authors.initials: M
authors.lastname: Kitajima
authors.forename: Toshinori
authors.initials: T
authors.lastname: Hirai
authors.forename: Shoji
authors.initials: S
authors.lastname: Morishita
authors.forename: Kazuo
authors.initials: K
authors.lastname: Awai
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000328:Adult; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005189:False Positive Reactions; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D012189:Retrospective Studies; D012680:Sensitivity and Specificity