title: Tissue shrinkage in microwave ablation of liver: an ex vivo predictive model.
abstract: The aim of this study was to develop a predictive model of the shrinkage of liver tissues in microwave ablation.
  
  
  
  Thirty-seven cuboid specimens of ex vivo bovine liver of size ranging from 2 cm to 8 cm were heated exploiting different techniques: 1) using a microwave oven (2.45 GHz) operated at 420 W, 500 W and 700 W for 8 to 20 min, achieving complete carbonisation of the specimens, 2) using a radiofrequency ablation apparatus (450 kHz) operated at 70 W for a time ranging from 6 to 7.5 min obtaining white coagulation of the specimens, and 3) using a microwave (2.45 GHz) ablation apparatus operated at 60 W for 10 min. Measurements of specimen dimensions, carbonised and coagulated regions were performed using a ruler with an accuracy of 1 mm. Based on the results of the first two experiments a predictive model for the contraction of liver tissue from microwave ablation was constructed and compared to the result of the third experiment.
  
  
  
  For carbonised tissue, a linear contraction of 31 ± 6% was obtained independently of the heating source, power and operation time. Radiofrequency experiments determined that the average percentage linear contraction of white coagulated tissue was 12 ± 5%. The average accuracy of our model was determined to be 3 mm (5%).
  
  
  
  The proposed model allows the prediction of the shrinkage of liver tissues upon microwave ablation given the extension of the carbonised and coagulated zones. This may be useful in helping to predict whether sufficient tissue volume is ablated in clinical practice.
authors.affiliation: a R&D Unit, H.S. Hospital Service SpA , Rome.
authors.forename: Claudio
authors.initials: C
authors.lastname: Amabile
authors.affiliation: b Department of Information Engineering, Electronics and Telecommunications , Sapienza University of Rome , Rome.
authors.forename: Laura
authors.initials: L
authors.lastname: Farina
authors.affiliation: c Division of Health Protection Technologies , Casaccia Research Centre, Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) , Rome , Italy.
authors.forename: Vanni
authors.initials: V
authors.lastname: Lopresto
authors.affiliation: c Division of Health Protection Technologies , Casaccia Research Centre, Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) , Rome , Italy.
authors.forename: Rosanna
authors.initials: R
authors.lastname: Pinto
authors.affiliation: a R&D Unit, H.S. Hospital Service SpA , Rome.
authors.forename: Simone
authors.initials: S
authors.lastname: Cassarino
authors.affiliation: a R&D Unit, H.S. Hospital Service SpA , Rome.
authors.forename: Nevio
authors.initials: N
authors.lastname: Tosoratti
authors.affiliation: d Department of Radiology, Hadassah Hebrew University Medical Center, Jerusalem, Israel, and Department of Radiology , Beth Israel Deaconess Medical Center , Boston , Massachusetts , USA.
authors.forename: S Nahum
authors.initials: SN
authors.lastname: Goldberg
authors.affiliation: b Department of Information Engineering, Electronics and Telecommunications , Sapienza University of Rome , Rome.
authors.forename: Marta
authors.initials: M
authors.lastname: Cavagnaro
mesh_terms: D055011:Ablation Techniques; D000818:Animals; D002417:Cattle; D006979:Hyperthermia, Induced; D008099:Liver / Q000601:surgery*; D008872:Microwaves; D008954:Models, Biological
keywords: Ablation; contraction; microwave; model; shrinkage; tumour