title: Study of the relationship between the target tissue necrosis volume and the target tissue size in liver tumours using two-compartment finite element RFA modelling.
abstract: OBJECTIVE
  The aim of this study was to investigate the relationship between the target tissue necrosis volume and the target tissue size during the radiofrequency ablation (RFA) procedure.
  
  
  METHODS
  The target tissues with four different sizes (dxy = 20, 25, 30 and 35 mm) were modelled using a two-compartment radiofrequency ablation model. Different voltages were applied to seek the maximum target tissue necrosis volume for each target tissue size. The first roll-off occurrence or the standard ablation time (12 min) was taken as the sign for the termination of the RFA procedure.
  
  
  RESULTS
  Four different maximum voltages without the roll-off occurrence were found for the four different sizes of target tissues (dxy = 20, 25, 30 and 35 mm), and they were 36.6, 35.4, 33.9 and 32.5 V, respectively. The target tissues with diameters of 20, 25 mm can be cleanly ablated at their own maximum voltages applied (MVA) but the same finding was not found for the 35-mm target tissue. For the target tissue with diameter of 30 mm, the 50 °C isothermal contour (IT50) result showed that the target tissue can be cleanly ablated, but the same result did not show in the Arrhenius damage model result. Furthermore, two optimal RFA protocols with a minimal thermal damage to the healthy tissues were found for the target tissues with diameters of 20 and 25 mm, respectively.
  
  
  CONCLUSIONS
  The study suggests that target tissues of different sizes should be treated with different RFA protocols. The maximum target tissue volume was achieved with the MVA without the roll-off occurrence for each target tissue size when a constant RF power supply was used.
authors.affiliation: Complex and Intelligent Systems Centre, School of Mechanical and Power Engineering, East China University Science and Technology , Shanghai , China .
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.forename: Michael A J
authors.initials: MA
authors.lastname: Moser
authors.forename: Edwin M
authors.initials: EM
authors.lastname: Zhang
authors.forename: Yigang
authors.initials: Y
authors.lastname: Luo
authors.forename: Hongbo
authors.initials: H
authors.lastname: Zhang
authors.forename: Wenjun
authors.initials: W
authors.lastname: Zhang
mesh_terms: D017115:Catheter Ablation / Q000379:methods*; D003198:Computer Simulation; D020342:Finite Element Analysis; D006801:Humans; D008113:Liver Neoplasms / Q000601:surgery*; D008962:Models, Theoretical; D009336:Necrosis / Q000473:pathology*; D047368:Tumor Burden
keywords: Finite element analysis; Liver tumour; radiofrequency ablation; roll-off occurrence; target tissue necrosis