title: Intravoxel Incoherent Motion Diffusion Weighted MR Imaging for Monitoring the Instantly Therapeutic Efficacy of Radiofrequency Ablation in Rabbit VX2 Tumors without Evident Links between Conventional Perfusion Weighted Images.
abstract: OBJECTIVE
  To investigate the intravoxel incoherent motion diffusion weighted imaging (IVIM-DWI) as a potential valuable marker to monitor the therapy responses of VX2 to radiofrequency ablation (RF Ablation).
  
  
  METHODS
  The institutional animal care and use committee approved this study. In 10 VX2 tumor-bearing rabbits, IVIM-DWI examinations were performed with a 3.0T imaging unit by using 16 b values from 0 to 800 sec/mm2. The true diffusion coefficient (D), pseudodiffusion coefficient (D*) and perfusion fraction (f) of tumors were compared between before and instantly after RF Ablation treatment. The differences of D, D* and f and conventional perfusion parameters (from perfusion CT and dynamic enhanced magnetic resonance imaging, DCE-MRI) in the coagulation necrosis area, residual unablated area, untreated area, and normal control had been calculated by compared t-test. The correlation between f or D* with perfusion weighted CT including blood flow, BF (milliliter per 100 mL/min), blood volume, BV (milliliter per 100 mL/min), and capillary permeability-surface area, PMB (as a fraction) or from DCE-MRI: transfer constant (Ktrans), extra-vascular extra-cellular volume fraction (Ve) and reflux constant (Kep) values had been analyzed by region-of-interest (ROI) methods to calculate Pearson's correlation coefficients.
  
  
  RESULTS
  In the ablated necrosis areas, f and D* significantly decreased and D significantly increased, compared with residual unblazed areas or untreated control groups and normal control groups (P < 0.001). The IVIM-DWI derived f parameters showed significant increases in the residual unablated tumor area. There was no significant correlations between f or D* and conventional perfusion parameters.
  
  
  CONCLUSIONS
  The IVIM-DW derived f, D and D* parameters have the potential to indicate therapy response immediately after RF Ablation treatment, while no significant correlations with classical tumor perfusion metrics were derived from DCE-MRI and perfusion-CT measurements.
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China; Department of Radiology, Haikou People's Hospital, Xiangya Medical School, Central South University, Haikou, 570208, Hainan, P.R. China.
authors.forename: Ziyi
authors.initials: Z
authors.lastname: Guo
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China.
authors.forename: Xiaoguang
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China.
authors.forename: Zhengyu
authors.initials: Z
authors.lastname: Jing
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000379:methods*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D009374:Neoplasms, Experimental / Q000000981:diagnostic imaging* / Q000601:surgery*; D011817:Rabbits; D011859:Radiography