title: Experimental evaluation of accuracy of radiofrequency ablation using conventional ultrasound or a third-dimension navigation tool.
abstract: BACKGROUND
  Successful radiofrequency-induced ablation is dependent on correct placement of the device. The ultraguide system is a three-dimensional positioning system creating an overlay of the real-time ultrasound image and a virtual image of the device.
  
  
  METHODS
  Tumor mimics were produced by injecting an agarose/cellulose/glycerol gel into pig livers on table. The precision of device placement was evaluated either using a freehand ultrasound procedure or using the aid of the ultraguide system either by an experienced or inexperienced surgeon. Tumor mimics were ablated by a protocol yielding an ablation only discretely larger than the mimics to enhance the importance of precise positioning.
  
  
  RESULTS
  The sizes of the 40 tumor mimics were: largest diameter 14.1+/-2.2 mm, volume 0.89+/-0.40 cm(3). The largest diameter of ablation was 25.6+/-3.7 mm, the smallest diameter 21.9+/-2.9 mm, and the volume 7.20+/-2.38 cm(3). The experienced surgeon was successful in 7 of 10 cases with and without the ultraguide, the inexperienced surgeon in 4 of 10 without and 7 of 10 with the ultraguide.
  
  
  CONCLUSIONS
  The ultraguide system may facilitate precise device placement for the less experienced surgeon. It seems worthwhile to evaluate a possible benefit of the system during placement of devices under operating room conditions.
authors.affiliation: Department of Visceral and Vascular Surgery, University of Cologne, Joseph-Stelzmann-Strasse 9, Germany. Dirk.Stippel@uni-koeln.de
authors.forename: Dirk L
authors.initials: DL
authors.lastname: Stippel
authors.forename: Sebastian
authors.initials: S
authors.lastname: Böhm
authors.forename: K Tobias E
authors.initials: KT
authors.lastname: Beckurts
authors.forename: Hans G
authors.initials: HG
authors.lastname: Brochhagen
authors.forename: Arnulf H
authors.initials: AH
authors.lastname: Hölscher
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation*; D003199:Computer Systems; D004195:Disease Models, Animal; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation*; D066298:In Vitro Techniques; D008114:Liver Neoplasms, Experimental / Q000000981:diagnostic imaging* / Q000601:surgery*; D015203:Reproducibility of Results; D025321:Surgery, Computer-Assisted / Q000295:instrumentation*; D013552:Swine; D018608:Ultrasonography, Doppler / Q000295:instrumentation*