title: 3D ultrasound-based navigation for radiofrequency thermal ablation in the treatment of liver malignancies.
abstract: BACKGROUND
  The aim of the study was to compare three methods for ultrasound-based guidance of a radiofrequency probe into liver tumors in a model setup.
  
  
  METHODS
  The liver model tumors were placed inside excised calf livers, and the radiofrequency probe was guided into the center using either a new 3D navigation method or two conventional 2D methods-freehand scanning and a method based on a biopsy guide. We performed 54 experiments, measuring the physical distance (all methods) and image distance (3D method only) from the tip of the probe to the center of the tumors.
  
  
  RESULTS
  Based on the physical measurements alone, the biopsy-based guiding performed better than both the 2D freehand and the 3D navigation method. However, the 3D image measurements showed that the tip of the probe was better positioned in the center of the model tumors for the 3D navigation method as compared to the physical measurement results for the 2D methods.
  
  
  CONCLUSIONS
  Although it was easier to position the radiofrequency probe accurately using the 3D image display technique, movement of the model tumor during 3D navigation is a challenge.
authors.affiliation: SINTEF Unimed, Ultrasound, NO-7465 Trondheim, Norway.
authors.forename: E
authors.initials: E
authors.lastname: Sjølie
authors.forename: T
authors.initials: T
authors.lastname: Langø
authors.forename: B
authors.initials: B
authors.lastname: Ystgaard
authors.forename: G A
authors.initials: GA
authors.lastname: Tangen
authors.forename: T A
authors.initials: TA
authors.lastname: Nagelhus Hernes
authors.forename: R
authors.initials: R
authors.lastname: Mårvik
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods* / Q000639:trends; D002417:Cattle; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000379:methods* / Q000639:trends; D008099:Liver / Q000000981:diagnostic imaging / Q000601:surgery; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*; D018084:Ultrasonography, Interventional / Q000295:instrumentation / Q000379:methods / Q000639:trends