Measurement and prediction of thermal behavior and acute assessment of injury in a pig model of renal cryosurgery.
OBJECTIVE
To analyze in vivo end temperatures and histologic injury in a standardized cryo-iceball using a porcine kidney model in order to establish the threshold temperature for tissue ablation. To evaluate the ability to predict end temperatures using a thermal finite element model.


METHODS
A single freeze/thaw cryolesion was created in five pig kidneys and the temperature history recorded. End temperature was calculated using a thermal finite element model. The threshold temperature for tissue injury was established by directly correlating end temperature and histologic injury.


RESULTS
Reproducible geometry and temperature profiles of the cryo-iceball were found. End temperature could be accurately predicted through thermal modeling, and correlation with histologic injury revealed a threshold temperature of -16.1 degrees C for complete tissue ablation.


CONCLUSIONS
Thermal modeling may accurately predict end temperature within a cryo-iceball. Provided threshold temperatures for tissue destruction are known, modeling may become a powerful tool in cryosurgery, improving the assessment of damage in normal and malignant tissue.
Schmidlin
F R
FR
Department of Urology, University of Minnesota, Medical School, Minneapolis 55455, USA.
Rupp
C C
CC
Hoffmann
N E
NE
Coad
J E
JE
Swanlund
D J
DJ
Hulbert
J C
JC
Bischof
J C
JC
D000818:Animals; D003452:Cryosurgery / Q000009:adverse effects*; D004056:Differential Threshold; D007668:Kidney / Q000473:pathology* / Q000601:surgery*; D008962:Models, Theoretical; D015203:Reproducibility of Results; D013552:Swine; D013696:Temperature