title: In vivo validation of a therapy planning system for laser-induced thermotherapy (LITT) of liver malignancies.
abstract: OBJECTIVE
  In situ ablation is increasingly being used for the treatment of liver malignancies. The application of these techniques is limited by the lack of a precise prediction of the destruction volume. This holds especially true in anatomically difficult situations, such as metastases in the vicinity of larger liver vessels. We developed a three-dimensional (3D) planning system for laser-induced thermotherapy (LITT) of liver tumors. The aim of the study was to validate the system for calculation of the destruction volume.
  
  
  METHODS
  LITT (28 W, 20 min) was performed in close contact to major hepatic vessels in six pigs. After explantation of the liver, the coagulation area was documented. The liver and its vascular structures were segmented from a pre-interventional CT scan. Therapy planning was carried out including the cooling effect of adjacent liver vessels. The lesions in vivo and the simulated lesions were compared with a morphometric analysis.
  
  
  RESULTS
  The volume of lesions in vivo was 6,568.3 ± 3,245.9 mm(3), which was not different to the simulation result of 6,935.2 ± 2,538.5 mm(3) (P = 0.937). The morphometric analysis showed a sensitivity of the system of 0.896 ± 0.093 (correct prediction of destructed tissue). The specificity was 0.858 ± 0.090 (correct prediction of vital tissue).
  
  
  CONCLUSIONS
  A 3D computer planning system for the prediction of thermal lesions in LITT was developed. The calculation of the directional cooling effect of intrahepatic vessels is possible for the first time. The morphometric analysis showed a good correlation under clinical conditions. The pre-therapeutic calculation of the ablation zone might be a valuable tool for procedure planning.
authors.affiliation: Department of General, Vascular and Thoracic Surgery, Charité - University Medicine Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin, Germany. kai.lehmann@charite.de
authors.forename: Kai Siegfried
authors.initials: KS
authors.lastname: Lehmann
authors.forename: Bernd Benedikt
authors.initials: BB
authors.lastname: Frericks
authors.forename: Christoph
authors.initials: C
authors.lastname: Holmer
authors.forename: Andrea
authors.initials: A
authors.lastname: Schenk
authors.forename: Andreas
authors.initials: A
authors.lastname: Weihusen
authors.forename: Verena
authors.initials: V
authors.lastname: Knappe
authors.forename: Urte
authors.initials: U
authors.lastname: Zurbuchen
authors.forename: Heinz Otto
authors.initials: HO
authors.lastname: Peitgen
authors.forename: Heinz Johannes
authors.initials: HJ
authors.lastname: Buhr
authors.forename: Jörg Peter
authors.initials: JP
authors.lastname: Ritz
mesh_terms: D000818:Animals; D003198:Computer Simulation; D006285:Health Planning; D006979:Hyperthermia, Induced / Q000379:methods*; D007834:Lasers; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D034421:Sus scrofa; D014057:Tomography, X-Ray Computed