title: Precise characterization of renal parenchymal response to single and multiple cryoablation probes.
abstract: OBJECTIVE
  We characterized the size and shape of the ablated area, and the surrounding indeterminate zone associated with renal cryolesions produced by single and multiple cryoablation probe configurations in a porcine model.
  
  
  METHODS
  Laparoscopic cryoablation, consisting of 2, 10-minute double freeze cycles followed by a 3-minute active thaw, was performed in 18 pigs. Three groups of 6 pigs each were studied, including a single IceRod, 3 rods arranged in a triangular configuration 2 cm apart from each other and 4 rods arranged in a quadratic configuration 2 cm from each other. Cryoablated kidneys were harvested after 14 days for histopathological evaluation.
  
  
  RESULTS
  The mean diameter of the area of complete ablation produced by a 1, 3 and 4 rod configuration 1 cm from the tip of the rod was 2.0, 4.4 and 4.9 cm, respectively. Cryolesions were elliptical with 1 cryoablation probe and in the 3 and 4 rod configurations they conformed to triangular and quadratic cross-sectional shapes, respectively. In the zone, ablation a single small focus of peri-arteriolar renal cell viability was noted less than 1 mm from the edge of the cryolesion in 1 of the 18 cryolesions. Otherwise no viable renal cells were detected.
  
  
  CONCLUSIONS
  Multirod configurations can be used with templates to space cryoablation probes 2 cm apart from each other with reliable and complete ablation overlap between the rods. However, around larger blood vessels the ice ball must be extended to a larger margin to ensure complete tissue ablation.
authors.affiliation: Division of Urology, Washington University, St. Louis, Missouri, USA.
authors.forename: Kyle J
authors.initials: KJ
authors.lastname: Weld
authors.forename: Greg
authors.initials: G
authors.lastname: Hruby
authors.forename: Peter A
authors.initials: PA
authors.lastname: Humphrey
authors.forename: Caroline D
authors.initials: CD
authors.lastname: Ames
authors.forename: Jaime
authors.initials: J
authors.lastname: Landman
mesh_terms: D000818:Animals; D003452:Cryosurgery / Q000706:statistics & numerical data*; D007668:Kidney / Q000473:pathology* / Q000601:surgery*; D013552:Swine