title: Laboratory and animal model evaluation of the Cryotech LCS 2000 in hepatic cryotherapy.
abstract: Hepatic cryotherapy is increasingly used in the treatment of patients with multiple hepatic metastases, particularly from colorectal cancer. The Cryotech LCS 2000 system, with insulated shaft-circulated liquid nitrogen probes, was designed for this purpose and was evaluated on the bench and in an animal model. The 9-mm probe was considerably more effective than the 5-mm probe when judged on time to create an iceball of a given diameter. The use of thawing gas reduced the time until the probe could be removed from 25 to 5 min but heated gas only produced a further reduction of 2 min. In the animal model, significant reduction in treatment times occurred with vascular inflow occlusion. The zone of necrosis as a percentage of the original iceball diameter was significantly higher following a twin freeze/thaw cycle. The relationship of the edge of the iceball to the eventual zone of hepatic necrosis was studied using different unabsorbable markers. India ink and sutures proved unreliable but a Teflon cannula was more successful and the margin was only of the order of 2 mm. The discrepancy between this observation and the percentage of the original iceball diameter which apparently becomes necrotic (64 and 82%) for single- and double-freeze lesions, respectively, suggests that the cryolesion undergoes shrinkage within 1 month and that the diameter of necrosis underestimates the true zone of destruction.
authors.affiliation: Department of Surgery, St. George Hospital, Kogarah, Sydney, New South Wales, Australia.
authors.forename: A V
authors.initials: AV
authors.lastname: Dilley
authors.forename: D Y
authors.initials: DY
authors.lastname: Dy
authors.forename: A
authors.initials: A
authors.lastname: Warlters
authors.forename: S
authors.initials: S
authors.lastname: Copeland
authors.forename: A E
authors.initials: AE
authors.lastname: Gillies
authors.forename: R W
authors.initials: RW
authors.lastname: Morris
authors.forename: D B
authors.initials: DB
authors.lastname: Gibb
authors.forename: T A
authors.initials: TA
authors.lastname: Cook
authors.forename: D L
authors.initials: DL
authors.lastname: Morris
mesh_terms: D000818:Animals; D003452:Cryosurgery / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D005069:Evaluation Studies as Topic; D007053:Ice; D066298:In Vitro Techniques; D008099:Liver / Q000473:pathology / Q000601:surgery*; D008113:Liver Neoplasms / Q000556:secondary / Q000601:surgery; D008297:Male; D009336:Necrosis; D012756:Sheep; D013997:Time Factors
chemical_list: D007053:Ice