title: The value of diffusion-weighted imaging for monitoring the chemotherapeutic response of osteosarcoma: a comparison between average apparent diffusion coefficient and minimum apparent diffusion coefficient.
abstract: OBJECTIVE
  The objective of this study was to evaluate whether the average apparent diffusion coefficient (ADC) or the minimum ADC is more useful for evaluating the chemotherapeutic response of osteosarcoma.
  
  
  METHODS
  Twenty-two patients with osteosarcoma were examined in this study. Diffusion-weighted (DW) and magnetic resonance (MR) images were performed for all patients before and after chemotherapy. The pre- and post-chemotherapy values were obtained both in the average and minimum ADC. The pre-chemotherapy values of the average ADC and minimum ADC respectively were compared with the post-chemotherapy values. In addition, the ADC ratios ([ADC(post) - ADC(pre)] / ADC(pre)) were calculated using the average ADC and the minimum ADC. Twenty-two patients with osteosarcomas were divided into two groups, those with a good response to chemotherapy (> or = 90% tumor necrosis, n = 7) and those with a poor response (< 90% tumor necrosis, n = 15). The average ADC ratio and the minimum ADC ratio of the two groups were compared.
  
  
  RESULTS
  With both the average ADC and the minimum ADC, post-chemotherapy values were significantly higher than pre-chemotherapy values (P < 0.05). The patients with a good response had a significantly higher minimum ADC ratio than those with a poor response (1.01 + or - 0.22 and 0.55 + or - 0.29 respectively, P < 0.05). However, with regard to the average ADC ratio, no significant difference was observed between the two groups (0.66 + or - 0.18 and 0.46 + or - 0.31 respectively, P = 0.19).
  
  
  CONCLUSIONS
  The minimum ADC is useful for evaluating the chemotherapeutic response of osteosarcoma.
authors.affiliation: Department of Orthopaedic and Neuro-Musculoskeletal Surgery, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto, Japan 860-0811. okaokay5888@yahoo.co.jp
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Oka
authors.forename: Toshitake
authors.initials: T
authors.lastname: Yakushiji
authors.forename: Hiro
authors.initials: H
authors.lastname: Sato
authors.forename: Toshinori
authors.initials: T
authors.lastname: Hirai
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mizuta
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001859:Bone Neoplasms / Q000175:diagnosis* / Q000188:drug therapy*; D002648:Child; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D012516:Osteosarcoma / Q000175:diagnosis* / Q000188:drug therapy*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000970:Antineoplastic Agents