title: ADC value and diffusion tensor imaging of prostate cancer: changes in carbon-ion radiotherapy.
abstract: OBJECTIVE
  To assess the apparent diffusion coefficient (ADC) value and diffusion tensor image (DTI) including fractional anisotropy (FA) of the noncancerous prostate and prostate cancer before and after carbon-ion radiotherapy (CIRT).
  
  
  METHODS
  Nine patients with biopsy-proven prostate cancer underwent 1.5T magnetic resonance (MR) examinations. One patient with benign prostatic hypertrophy and one healthy volunteer were also examined as references. The changes in ADC values and DTI of the entire prostate calculated from b-values of 0 and 700 (s/mm(2)) were estimated between before and after CIRT.
  
  
  RESULTS
  ADC values of prostate cancer significantly increased after CIRT by paired t-test (P < 0.01) but those of noncancerous inner gland (IG) and peripheral zone (PZ) showed no significant change. By analysis of variance, significant differences in ADC values were observed among prostate cancer and noncancerous IG and PZ before CIRT (P < 0.05). After CIRT, those significant differences had disappeared. FAs showed no significant differences in any comparisons. DTI showed changes in the direction of the main axis of the tensor in prostate cancer after CIRT.
  
  
  CONCLUSIONS
  There were changes in ADC and DTI in prostate cancer after CIRT. They may be useful for monitoring prostatic structural changes under radiotherapy.
authors.affiliation: Biophysics Group, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan.
authors.forename: Yukihisa
authors.initials: Y
authors.lastname: Takayama
authors.forename: Riwa
authors.initials: R
authors.lastname: Kishimoto
authors.forename: Shouhei
authors.initials: S
authors.lastname: Hanaoka
authors.forename: Hiroi
authors.initials: H
authors.lastname: Nonaka
authors.forename: Susumu
authors.initials: S
authors.lastname: Kandatsu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsuji
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Tsujii
authors.forename: Hiroo
authors.initials: H
authors.lastname: Ikehira
authors.forename: Takayuki
authors.initials: T
authors.lastname: Obata
mesh_terms: D000368:Aged; D016880:Anisotropy; D002250:Carbon Radioisotopes / Q000627:therapeutic use*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D063193:Heavy Ion Radiotherapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011467:Prostate / Q000473:pathology; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000532:radiotherapy*
chemical_list: D002250:Carbon Radioisotopes