title: Noninvasive assessment of response to neoadjuvant chemotherapy in osteosarcoma of long bones with diffusion-weighted imaging: an initial in vivo study.
abstract: OBJECTIVE
  The purpose of our study is to investigate whether diffusion-weighted imaging (DWI) is useful for monitoring the therapeutic response after neoadjuvant chemotherapy in osteosarcoma of long bones.
  
  
  METHODS
  Conventional magnetic resonance imaging (MRI) and DWI were obtained from 35 patients with histologically proven osteosarcomas. MR examinations were performed in all patients before and after 4 courses of preoperative neoadjuvant chemotherapy. Apparent diffusion coefficients (ADC) were measured. The degree of tumor necrosis was assessed macroscopically and histologically by two experienced pathologists after operation. Student's t test was performed for testing changes in ADC value. Pearson's correlation coefficient was used to estimate the correlation between necrosis rate and post- neoadjuvant chemotherapy ADC values. P<0.05 was considered to denote a significant difference.
  
  
  RESULTS
  The difference of the whole osteosarcoma between pre- neoadjuvant chemotherapy ADC value (1.24±0.17×10(-3) mm(2)/s) and post- (1.93±0.39×10(-3) mm(2)/s) was significant difference (P<0.01). Regarding in patients with good response, the post- neoadjuvant chemotherapy values were significantly higher than the pre- neoadjuvant chemotherapy values (P<0.01). The post- neoadjuvant chemotherapy ADC value in patients with good response was higher than that of poor response (t = 8.995, P<0.01). The differences in post- neoadjuvant chemotherapy ADC between viable (1.03±0.17×10(-3) mm(2)/s) and necrotic (2.38±0.25×10(-3) mm(2)/s) tumor was highly significant (t = 23.905, P<0.01). A positive correlation between necrosis rates and the whole tumor ADC values (r = 0.769, P<0.01) was noted, but necrosis rates were not correlated with the ADC values of necrotic (r = -0.191, P = 0.272) and viable tumor areas (r = 0.292, P = 0.089).
  
  
  CONCLUSIONS
  DWI can identify residual viable tumor tissues and tumor necrosis induced by neoadjuvant chemotherapy in osteosarcoma. The ADC value can directly reflect the degree of tumor necrosis, and it is useful to evaluate the preoperative neoadjuvant chemotherapy response in patients with osteosarcoma.
authors.affiliation: Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Cheng-Sheng
authors.initials: CS
authors.lastname: Wang
authors.forename: Lian-Jun
authors.initials: LJ
authors.lastname: Du
authors.forename: Ming-Jue
authors.initials: MJ
authors.lastname: Si
authors.forename: Qi-Hua
authors.initials: QH
authors.lastname: Yin
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.forename: Min
authors.initials: M
authors.lastname: Shu
authors.forename: Fei
authors.initials: F
authors.lastname: Yuan
authors.forename: Xiao-Chun
authors.initials: XC
authors.lastname: Fei
authors.forename: Xiao-Yi
authors.initials: XY
authors.lastname: Ding
mesh_terms: D000328:Adult; D001859:Bone Neoplasms / Q000188:drug therapy / Q000473:pathology*; D017024:Chemotherapy, Adjuvant; D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D008297:Male; D012516:Osteosarcoma / Q000188:drug therapy / Q000473:pathology*; D016896:Treatment Outcome