Temperature isotherms during pulmonary cryoablation and their correlation with the zone of ablation.
OBJECTIVE
To determine the expected ablation zone size and associated isotherms when using clinically available percutaneous cryoprobes for pulmonary cryoablation in a porcine lung model.


METHODS
Seven ablations were performed in the lungs of three adult pigs using clinically available 2.4-mm cryoprobes (Endocare, Inc, Irvine, California) and a 10-minute double-freeze protocol. Five 18-gauge thermocouples were positioned at 5-mm increments (ie, 5, 10, 15, 20, and 25 mm) from the cryoprobe. Real-time tissue temperatures were recorded during the cryoablation. The isotherms obtained during the ablation and the pathological ablation zones were measured.


RESULTS
The pathologic zone of complete necrosis had a mean diameter of 2.4 + or - 0.2 cm, with a mean area of 4.6 + or - 0.6 cm(2) and a circularity of 0.95 + or - 0.04. In comparison, the mean diameter (+ or - standard deviation) of the 0 degrees C, -20 degrees C, and -40 degrees C isotherms were 3.1 + or - 0.2 cm, 2.3 + or - 0.3 cm, and 1.8 + or - 0.4 cm, respectively. The -20 degrees C isotherm was most closely related to the pathologic zone of ablation.


CONCLUSIONS
This study establishes the temperature isotherms and associated ablation zone size that can be expected with modern percutaneous cryoprobes in an in vivo porcine lung model.
Hinshaw
J Louis
JL
University of Wisconsin Department of Radiology, E3/311 CSC, 600 Highland Avenue, Madison, WI 53792, USA. jhinshaw@uwhealth.org
Lee
Fred T
FT
Laeseke
Paul F
PF
Sampson
Lisa A
LA
Brace
Christopher
C
D000818:Animals; D003080:Cold Temperature; D003452:Cryosurgery / Q000295:instrumentation; D004867:Equipment Design; D005260:Female; D008168:Lung / Q000473:pathology / Q000601:surgery*; D023421:Models, Animal; D009336:Necrosis; D034421:Sus scrofa; D013997:Time Factors