title: Cavitation enhances coagulated size during pulsed high-intensity focussed ultrasound ablation in an isolated liver perfusion system.
abstract: OBJECTIVE
  To investigate whether cavitation enhances the degree of coagulation during pulsed high-intensity focussed ultrasound (HIFU) in an isolated liver perfusion system.
  
  
  METHODS
  Isolated liver was treated by pulsed HIFU or continuous-wave HIFU with different portal vein flow rates. The cavitation emission during exposure was recorded, and real-time ultrasound images were used to observe changes in the grey scale. The coagulation size was measured and calculated.
  
  
  RESULTS
  HIFU treatment led to complete coagulation necrosis and total cell destruction in the target regions. Compared to exposure at a duty cycle (DC) of 100%, the mean volumes of lesions induced by 6 s exposure at DCs of 50% and 10% were significantly larger (P < .01) but were smaller at a DC of 5%. The necrosis volume was negatively related to the perfusion rate in the pulsed HIFU at a DC of 50% for exposure durations of 4 and 6 s, while the perfusion flow rate did not affect the necrosis volume for exposure durations of 1, 2 and 3 s. For increased perfusion flow rates, there was no significant decrease in the cavitation activity for the pulsed-HIFU (P > .05). For continuous-wave HIFU exposure, there was a significant decrease in the necrosis volume and cavitation activity for exposure times of 1, 2, 3, 4, and 6 s with increasing portal perfusion rates.
  
  
  CONCLUSIONS
  Perfusion flow rates negatively influence cavitation activity and coagulation volume. Ablation is significantly enhanced during pulsed HIFU exposure compared with continuous-wave HIFU.
authors.affiliation: a State Key Laboratory of Ultrasound Engineering in Medicine , College of Biomedical Engineering, Chongqing Medical University , Chongqing , China.|b Department of Gynecology and Obstetrics, Xi'dian Group Hospital , Shaanxi Xi'an , China.
authors.forename: Lu-Yan
authors.initials: LY
authors.lastname: Zhao
authors.affiliation: a State Key Laboratory of Ultrasound Engineering in Medicine , College of Biomedical Engineering, Chongqing Medical University , Chongqing , China.
authors.forename: Shan
authors.initials: S
authors.lastname: Liu
authors.affiliation: a State Key Laboratory of Ultrasound Engineering in Medicine , College of Biomedical Engineering, Chongqing Medical University , Chongqing , China.
authors.forename: Zong-Gui
authors.initials: ZG
authors.lastname: Chen
authors.affiliation: a State Key Laboratory of Ultrasound Engineering in Medicine , College of Biomedical Engineering, Chongqing Medical University , Chongqing , China.
authors.forename: Jian-Zhong
authors.initials: JZ
authors.lastname: Zou
authors.affiliation: a State Key Laboratory of Ultrasound Engineering in Medicine , College of Biomedical Engineering, Chongqing Medical University , Chongqing , China.|c Nuffield Department of Surgical Sciences , University of Oxford , Oxford , UK.
authors.forename: Feng
authors.initials: F
authors.lastname: Wu
keywords: Cavitation; focussed ultrasound; high-intensity focused; perfusion flow rate; porcine liver perfusion; thermal ablation