title: Perivascular and intralesional tissue necrosis after hepatic cryoablation: results in a porcine model.
abstract: BACKGROUND
  Cryosurgical ablation of malignant hepatic tumors is being increasingly used for definitive treatment of metastatic colorectal and primary hepatic tumors. The lack of tumor necrosis near vessels that results from inadequate freezing may contribute to local recurrence and thus limit the applications of this therapy. This study was designed to determine whether single-freeze cryoablation could cause necrosis of both the pervascular and intralesional hepatic parenchyma.
  
  
  METHODS
  Ten pigs were treated with one 15-minute cycle of cryoablation. Five additional animals were treated with overlapping cryolesions to simulate a double freeze. After 24 hours, animals underwent reoperation with portal vein cannulation and infusion of formalin. Serial sectioning and hematoxylin and eosin staining of cryolesions were performed.
  
  
  RESULTS
  Complete cell death was visualized within all cryolesions. There was no difference between once or twice-frozen tissue. Vessels within or adjacent to cryolesions showed necrosis of hepatic tissue up to the vessel wall. No sections revealed incomplete necrosis of perivascular hepatic parenchyma.
  
  
  CONCLUSIONS
  Single-freeze cryoablation results in necrosis of intralesional hepatic parenchyma without added benefit from repeat freezing. Complete necrosis of the perivascular tissue suggests that cryosurgical ablation can effectively cause necrosis immediately adjacent to vessels without concerns of incomplete ablation resulting from the heat sink effect.
authors.affiliation: Department of Surgery, University of Wisconsin School of Medicine, Madison, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Weber
authors.forename: F T
authors.initials: FT
authors.lastname: Lee
authors.forename: D O
authors.initials: DO
authors.lastname: Chinn
authors.forename: T
authors.initials: T
authors.lastname: Warner
authors.forename: S G
authors.initials: SG
authors.lastname: Chosy
authors.forename: D M
authors.initials: DM
authors.lastname: Mahvi
mesh_terms: D000818:Animals; D016923:Cell Death; D003452:Cryosurgery / Q000009:adverse effects*; D005557:Formaldehyde; D006498:Hepatectomy / Q000009:adverse effects*; D007262:Infusions, Intravenous; D008099:Liver / Q000473:pathology*; D008113:Liver Neoplasms / Q000601:surgery; D009336:Necrosis; D011169:Portal Vein; D012086:Reoperation; D013552:Swine; D013927:Thrombosis / Q000209:etiology / Q000473:pathology
chemical_list: D005557:Formaldehyde