title: Dynamic characteristics of MR diffusion-weighted imaging in a rabbit liver VX-2 tumor model.
abstract: OBJECTIVE
  To investigate prospectively dynamic characteristics of the apparent diffusion coefficient (ADC) on MR diffusion-weighted imaging (DWI) in a rabbit VX-2 tumor model.
  
  
  METHODS
  Forty New Zealand rabbits were included in the study, and 47 rabbit VX-2 tumor models were developed by direct and intrahepatic implantation after opening the abdominal cavities. DWI was carried out periodically and respectively on days 7, 14 and 21 after implantation. The VX-2 tumor samples were studied by pathology. The distinction of VX-2 tumors on DWI was assessed by their ADC values by analysis of variance (ANOVA) using SPSS12.0 software.
  
  
  RESULTS
  The ADC values (mean ± SD) × 10(-3) mm(2)/s of 47 VX-2 tumors in the peripheral and central areas were 2.18 ± 0.29, 1.96 ± 0.33, 1.80 ± 0.35, 2.20 ± 0.29, 2.05 ± 0.30 and 1.96 ± 0.48, respectively, on days 7, 14 and 21 after implantation. ADC values of 47 VX-2 tumors in the area of the tumor periphery, center and normal parenchyma were higher when the b-value was 100 s/mm(2) than those when the b-value was 300 s/mm(2) (F = 17.964, p < 0.001; F = 13.986, p < 0.001; F = 128.681, p < 0.001). ADC values in the area of normal liver parenchyma were higher than those in the area of the VX-2 tumor periphery and center when the b-value was 100 or 300 s/mm(2). ADCs of viable tumor cells in VX-2 tumors were lower on DWI than those in the area of normal liver parenchyma around the tumor, and ADCs of dead tumor cells in VX-2 tumors were unequal, including high, equal and low values, but they were higher than in the area of normal liver parenchyma around tumors after dead tumor cells had been liquefied or had become cystic.
  
  
  CONCLUSIONS
  ADC is correlated with the tumor histology and degree of malignancy, and DWI has potential value for dynamically monitoring tumors and evaluating the degree of malignancy and therapeutic effect.
authors.affiliation: Department of Radiology, The Second Xiang-Ya Hospital, Central South University, Changsha 410012, Hunan, China.
authors.forename: You-Hong
authors.initials: YH
authors.lastname: Yuan
authors.forename: En-Hua
authors.initials: EH
authors.lastname: Xiao
authors.forename: Zhong
authors.initials: Z
authors.lastname: He
authors.forename: Ke
authors.initials: K
authors.lastname: Jin
authors.forename: Cong
authors.initials: C
authors.lastname: Ma
authors.forename: Jun
authors.initials: J
authors.lastname: Xiang
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Xiao
authors.forename: Wei-Jian
authors.initials: WJ
authors.lastname: Chen
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004195:Disease Models, Animal; D008099:Liver / Q000473:pathology; D008114:Liver Neoplasms, Experimental / Q000473:pathology*; D011817:Rabbits