title: Intravoxel incoherent motion diffusion-weighted MRI for characterizing regional variability and monitoring serial changes of parameters in rabbit VX2 liver tumors.
abstract: OBJECTIVE
  To characterize intravoxel incoherent motion (IVIM) parameters in different regions of interest (ROIs) of rabbit VX2 liver tumors during a follow-up of 4 weeks.
  
  
  METHODS
  This study was approved by the Institutional Animal Care and Use Committee. In 18 VX2 liver tumor-bearing rabbits, IVIM DW imaging was serially performed at the 2nd, 3rd, and 4th week separately after tumor implantation at 1.5T by using 12 b values. Three ROIs were drawn on the apparent diffusion coefficient (ADC) maps, including the whole lesion, the visibly most restricted diffusion area (MRDA), and peripheral area of tumor. For each ROI of tumors, serial changes in ADC and D, D*, and f at three timepoints were calculated. The differences of IVIM parameters in different ROIs of tumors at each timepoint were compared.
  
  
  RESULTS
  Serial measurements of f in all three ROIs (P = 0.000, P = 0.002, and P = 0.000), ADC for the whole lesion, MRDA (P = 0.000 and P = 0.024), and D for MRDA (P = 0.001) from the 2nd to 4th week illustrated a statistical difference. The overall comparison of ADC (P = 0.000, P = 0.014, and P = 0.000), D (P = 0.000, P = 0.001, and P = 0.000), and f (P = 0.001, P = 0.001, and P = 0.000) for three tumor regions at weeks 2, 3, and 4 showed significant differences. D* in all three ROIs at each timepoint showed no significant differences (P = 0.612, P = 0.723, and P = 0.699; 95% confidence interval: 0.184-0.950).
  
  
  CONCLUSIONS
  The peripheral area of tumor could be used as an alternative to the whole lesion as ROIs to assess the VX2 liver tumor with IVIM DW imaging, and in the period between weeks 2 and 3.
authors.affiliation: Graduate College, Southern Medical University, Guangzhou, Guangdong Province, P.R. China.|Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R. China.
authors.forename: Haijun
authors.initials: H
authors.lastname: Wu
authors.affiliation: Graduate College, Southern Medical University, Guangzhou, Guangdong Province, P.R. China.|Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R. China.
authors.forename: Maoqing
authors.initials: M
authors.lastname: Hu
authors.affiliation: Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R. China.
authors.forename: Zaiyi
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R. China.
authors.forename: Weitao
authors.initials: W
authors.lastname: Ye
authors.affiliation: Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R. China.
authors.forename: Jinglei
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R. China.
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R. China.
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P.R. China.
authors.forename: Changhong
authors.initials: C
authors.lastname: Liang
mesh_terms: D000465:Algorithms; D000818:Animals; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008113:Liver Neoplasms / Q000473:pathology*; D008137:Longitudinal Studies; D009038:Motion; D010363:Pattern Recognition, Automated / Q000379:methods; D011817:Rabbits; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: VX2 rabbits; diffusion-weighted imaging; hepatocellular carcinoma; intravoxel incoherent motion