title: Magnetic resonance-guided focused ultrasound surgery (MRgFUS): ablation of liver tissue in a porcine model.
abstract: BACKGROUND
  Liver surgery is technically demanding and is considered a major procedure with relatively high morbidity rates. Magnetic resonance-guided focused ultrasound surgery (MRgFUS) uses focused ultrasonic energy to create a heat coagulation lesion, which can be achieved in a totally controlled, very accurate manner (<1 mm). The aim of this study was to evaluate the safety and accuracy of non-invasive focal ablation of liver tissue achieved by consecutive MRgFUS sonications.
  
  
  METHODS
  Six MRgFUS procedures were performed in five pigs under general anesthesia, with the ExAblate 2000 system (InSightec, Israel). Real-time imaging and temperature mapping (Signa Twinspeed 1.5T, GEHC, USA) enabled the immediate evaluation of the results of each sonication. Different foci were chosen within the liver. These mock lesions were ablated by several sonications, each of them performed during 20-30 s of apnea. Between sonications, the pigs were normally ventilated. The pigs were sacrificed 3-21 days after the procedure and their livers were examined.
  
  
  RESULTS
  The MRgFUS created complete tissue destruction of mock lesions in different areas of the pig's liver. The lesion sizes in each animal varied according to the number of sonications used and the extent of overlap between adjacent sonications. The lesion ranged in size from 1.5 cm x 1.5 cm x 2.0 cm to 5.5 cm x 4.5 cm x 2.0 cm. There was no morbidity.
  
  
  CONCLUSIONS
  MRgFUS under general anesthesia is a safe, completely non-invasive technology for the ablation of liver tissue. Liver tissue can be ablated in a very accurate manner, based on the pre-treatment planning on the MR images. The MR imaging characteristics, including real-time temperature mapping, enable real-time control of every step of the ablation process. Mechanical ventilation with intermittent periods of apnea is a technique that overcomes the problem of the respiratory movements of the liver.
authors.affiliation: Department of Surgery B, HaEmek Medical Center, Afula, Israel. Kopelman_d@clalit.org.il
authors.forename: Doron
authors.initials: D
authors.lastname: Kopelman
authors.forename: Yael
authors.initials: Y
authors.lastname: Inbar
authors.forename: Arik
authors.initials: A
authors.lastname: Hanannel
authors.forename: David
authors.initials: D
authors.lastname: Freundlich
authors.forename: David
authors.initials: D
authors.lastname: Castel
authors.forename: Azriel
authors.initials: A
authors.lastname: Perel
authors.forename: Adrian
authors.initials: A
authors.lastname: Greenfeld
authors.forename: Tal
authors.initials: T
authors.lastname: Salamon
authors.forename: Merab
authors.initials: M
authors.lastname: Sareli
authors.forename: Adrian
authors.initials: A
authors.lastname: Valeanu
authors.forename: Moshe
authors.initials: M
authors.lastname: Papa
mesh_terms: D000818:Animals; D004869:Equipment Safety; D008099:Liver / Q000473:pathology / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D023421:Models, Animal; D025321:Surgery, Computer-Assisted; D013552:Swine; D014464:Ultrasonic Therapy / Q000379:methods*