Precise characterization of renal parenchymal response to single and multiple cryoablation probes.
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.
Weld
Kyle J
KJ
Division of Urology, Washington University, St. Louis, Missouri, USA.
Hruby
Greg
G
Humphrey
Peter A
PA
Ames
Caroline D
CD
Landman
Jaime
J
D000818:Animals; D003452:Cryosurgery / Q000706:statistics & numerical data*; D007668:Kidney / Q000473:pathology* / Q000601:surgery*; D013552:Swine