title: US-guided application of Nd:YAG laser in porcine pancreatic tissue: an ex vivo study and numerical simulation.
abstract: BACKGROUND
  Laser ablation (LA) with a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser is a minimally invasive approach able to achieve a high rate of complete tissue necrosis. In a previous study we described the feasibility of EUS-guided Nd:YAG pancreas LA performed in vivo in a porcine model.
  
  
  OBJECTIVE
  To establish the best laser setting of Nd:YAG lasers for pancreatic tissue ablation. A secondary aim was to investigate the prediction capability of a mathematical model on ablation volume.
  
  
  METHODS
  Ex vivo animal study.
  
  
  METHODS
  Hospital animal laboratory.
  
  
  METHODS
  Explanted pancreatic glands from 60 healthy farm pigs.
  
  
  METHODS
  Laser output powers (OP) of 1.5, 3, 6, 10, 15, and 20 W were supplied. Ten trials for each OP were performed under US guidance on ex vivo healthy porcine pancreatic tissue.
  
  
  METHODS
  Ablation volume (Va) and central carbonization volume (Vc) were measured on histologic specimens as the sum of the lesion areas multiplied by the thickness of each slide. The theoretical model of the laser-tissue interaction was based on the Pennes equation.
  
  
  RESULTS
  A circumscribed ablation zone was observed in all histologic specimens. Va values grow with the increase of the OP up to 10 W and reach a plateau between 10 and 20 W. The trend of Vc values rises constantly until 20 W. The theoretical model shows a good agreement with experimental Va and Vc for OP between 1.5 and 10 W.
  
  
  CONCLUSIONS
  Ex vivo study.
  
  
  CONCLUSIONS
  Volumes recorded suggest that the best laser OP could be the lowest one to obtain similar Va with smaller Vc in order to avoid the risk of thermal injury to the surrounding tissue. The good agreement between the two models demonstrates the prediction capability of the theoretical model on laser-induced ablation volume in an ex vivo animal model and supports its potential use for estimating the ablation size at different laser OPs.
authors.affiliation: Digestive Endoscopy Unit Campus Bio-Medico, University of Rome, Rome, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Di Matteo
authors.forename: Margareth
authors.initials: M
authors.lastname: Martino
authors.forename: Roberta
authors.initials: R
authors.lastname: Rea
authors.forename: Monica
authors.initials: M
authors.lastname: Pandolfi
authors.forename: Francesco
authors.initials: F
authors.lastname: Panzera
authors.forename: Egidio
authors.initials: E
authors.lastname: Stigliano
authors.forename: Emiliano
authors.initials: E
authors.lastname: Schena
authors.forename: Paola
authors.initials: P
authors.lastname: Saccomandi
authors.forename: Sergio
authors.initials: S
authors.lastname: Silvestri
authors.forename: Claudio Maurizio
authors.initials: CM
authors.lastname: Pacella
authors.forename: Luca
authors.initials: L
authors.lastname: Breschi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Perrone
authors.forename: Roberto
authors.initials: R
authors.lastname: Coppola
authors.forename: Guido
authors.initials: G
authors.lastname: Costamagna
mesh_terms: D000535:Aluminum; D000818:Animals; D053685:Laser Therapy / Q000379:methods*; D053844:Lasers, Solid-State; D023421:Models, Animal; D009354:Neodymium; D010179:Pancreas / Q000601:surgery*; D025321:Surgery, Computer-Assisted / Q000379:methods; D013552:Swine; D018084:Ultrasonography, Interventional / Q000379:methods; D015019:Yttrium
chemical_list: C503779:yttrium-aluminum-garnet; D009354:Neodymium; D015019:Yttrium; D000535:Aluminum
keywords: LA; Nd:YAG; OP; Va; Vc; ablation volume; central carbonization volume; laser ablation; neodymium-doped yttrium aluminum garnet; output power