title: Navigated laparoscopy--liver shift and deformation due to pneumoperitoneum in an animal model.
abstract: BACKGROUND
  Precise laparoscopic liver resection requires accurate planning and visualization of important anatomy such as vessels and tumors. Combining laparoscopic ultrasound with navigation technology could provide this. Preoperative images are valuable for planning and overview of the procedure, while intraoperative images provide an updated view of the surgical field.
  
  
  OBJECTIVE
  To validate the accuracy of navigation technology based on preoperative images, we need to understand how much the liver shifts and deforms due to heartbeat, breathing, surgical manipulation and pneumoperitoneum. In this study, we evaluated liver tumor shift and deformation due to pneumoperitoneum in an animal model.
  
  
  METHODS
  Tumor models were injected into the liver of the animal, and 3D CT images were acquired before and after insufflation. Tumor shifts and deformation were determined.
  
  
  RESULTS
  The results showed significant tumor position shift due to pneumoperitoneum, with a maximum of 28 mm in cranio-caudal direction. No significant tumor deformation was detected. Small standard deviations suggest rigid body transformation of the liver as a whole, but this needs further investigation.
  
  
  CONCLUSIONS
  The findings indicate a need for anatomic shift correction of preoperative images before they are used in combination with LUS guidance during a laparoscopic liver resection procedure.
authors.affiliation: St. Antonius Hospital, Department of Medical Physics and Instrumentation, Nieuwegein, The Netherlands.
authors.forename: Mariken
authors.initials: M
authors.lastname: Zijlmans
authors.forename: Thomas
authors.initials: T
authors.lastname: Langø
authors.forename: Erlend Fagertun
authors.initials: EF
authors.lastname: Hofstad
authors.forename: Christiaan F P
authors.initials: CF
authors.lastname: Van Swol
authors.forename: Anna
authors.initials: A
authors.lastname: Rethy
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D007430:Intraoperative Care; D010535:Laparoscopy / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D008099:Liver / Q000601:surgery*; D008113:Liver Neoplasms / Q000473:pathology / Q000601:surgery*; D011027:Pneumoperitoneum / Q000473:pathology / Q000601:surgery*; D011300:Preoperative Care; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D013552:Swine