title: Effect of microbubble contrast agent during high intensity focused ultrasound ablation on rabbit liver in vivo.
abstract: OBJECTIVE
  To evaluate the effect of a microbubble contrast agent (SonoVue) during HIFU ablation of a rabbit liver.
  
  
  METHODS
  HIFU ablations (intensity of 400W/cm(2) for 4s, six times, with a 5s interval between exposures) were performed upon 16 in vivo rabbit livers before and after intravenous injection of a microbubble contrast agent (0.8ml). A Wilcoxon signed rank test was used to compare mean ablation volume and time required to tissue ablation on real-time US. Shape of ablation and pattern of coagulative necrosis were analyzed by Fisher's exact test.
  
  
  RESULTS
  The volume of coagulative necrosis was significantly larger in the combination microbubble and HIFU group than in the HIFU alone group (P<0.05). Also, time to reach ablation was shorter in the combination microbubble and HIFU group than in the HIFU alone group (P<0.05). When analyzing the shape of tissue ablation, a pyramidal shape was more prevalently in the HIFU alone group compared to the combination microbubble and HIFU group (P<0.05). Following an analysis of the pattern of coagulative necrosis, non-cavitary necrosis was found in ten and cavitary necrosis in six of the samples in the combination microbubble and HIFU group. Conversely, non-cavitary necrosis occurred in all 16 samples in the HIFU alone group (P<0.05).
  
  
  CONCLUSIONS
  HIFU of in vivo rabbit livers with a microbubble contrast agent produced larger zones of ablation and more cavitary tissue necrosis than without the use of a microbubble contrast agent. Microbubble contrast agents may be useful in tissue ablation by enhancing the treatment effect of HIFU.
authors.affiliation: Department of Radiology, Yeouido St. Mary's Hospital, The Catholic University of Korea, Republic of Korea. bookdoo7@chollian.net
authors.forename: Dong Jin
authors.initials: DJ
authors.lastname: Chung
authors.forename: Se Hyun
authors.initials: SH
authors.lastname: Cho
authors.forename: Jae Mun
authors.initials: JM
authors.lastname: Lee
authors.forename: Seong-Tae
authors.initials: ST
authors.lastname: Hahn
mesh_terms: D000818:Animals; D003287:Contrast Media; D006498:Hepatectomy / Q000379:methods*; D057086:High-Intensity Focused Ultrasound Ablation / Q000379:methods*; D008099:Liver / Q000000981:diagnostic imaging* / Q000601:surgery*; D045423:Microbubbles / Q000627:therapeutic use; D010743:Phospholipids / Q000627:therapeutic use*; D011817:Rabbits; D013459:Sulfur Hexafluoride / Q000627:therapeutic use*; D016896:Treatment Outcome; D014463:Ultrasonography
chemical_list: D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride