title: Influence of the target tissue size on the shape of ex vivo microwave ablation zones.
abstract: OBJECTIVE
  The aim of this study was to numerically and experimentally characterise the influence of tissues dimensions on the size and shape of microwave-induced ablation zones.
  
  
  METHODS
  A 2.45 GHz interstitial antenna was introduced into ex vivo bovine liver samples, delivering 60 W for 10 min; then the dimensions of the coagulated area were measured. Ablations were performed both in large samples (termed unrestricted tissue) for characterising the tissue response, and in thin samples, whose dimensions in the plane perpendicular to the antenna were smaller than the short axis of the ablated area obtained in unrestricted samples. In the numerical study the electromagnetic field emitted from the antenna and the corresponding temperature increase were evaluated in both unrestricted and thin tissue samples.
  
  
  RESULTS
  When the height of the tissue was smaller than the ablation diameter measured in unrestricted samples, a 7.5% increase in length of the ablated zone was experimentally observed. When both the height and width were lower than the diameter measured in unrestricted samples, an elongation of about 23.4% was experimentally obtained. The numerical study showed that the boundary conditions between the target tissue and the surrounding materials are critical.
  
  
  CONCLUSIONS
  The ex vivo performances of microwave ablation devices are notably influenced by the shape and dimension of the tissues where the procedure takes place. Accordingly, dedicated interventional protocols should be developed for treatment planning on targets of different shape and size.
authors: Department of Information Engineering, Electronics, Telecommunications, Sapienza University of Rome , Rome , Italy .
authors: Marta
authors: M
authors: Cavagnaro
authors: Claudio
authors: C
authors: Amabile
authors: Simone
authors: S
authors: Cassarino
authors: Nevio
authors: N
authors: Tosoratti
authors: Rosanna
authors: R
authors: Pinto
authors: Vanni
authors: V
authors: Lopresto
mesh_terms: D000818:Animals; D017115:Catheter Ablation; D002417:Cattle; D008099:Liver / Q000033:anatomy & histology* / Q000601:surgery*; D008872:Microwaves; D008962:Models, Theoretical; D009929:Organ Size
keywords: Heat transfer; modelling; radiofrequency/microwave; thermal ablation; treatment planning