Thermal Maps Around Two Adjacent Cryoprobes Creating Overlapping Ablations in Porcine Liver, Lung, and Kidney

Abstract

To determine cryoprobe spacing requirements in order to achieve overlapping ablation zones using the same ablation protocol in porcine liver, lung, and kidney. Six female pigs underwent cryoablation of the liver, lung, and kidney. Two 2.4-mm cryoprobes were spaced 20-mm apart with seven 16-gauge thermometers placed linearly and in axis with the cryoprobes at 5-mm increments from one another. The placement of the thermometers was such that three were placed between the two probes and two were placed laterally to each probe. Simultaneous use of the cryoprobes, using 12- and 8-minute double-freeze cycles, was performed with intratissue temperature monitoring during the procedure. The center temperatures between the two cryoprobes in kidney, lung, and liver were -25.87( degrees )C +/- 1.91, -6.47(degrees )C +/- 3.94, and 0.48( degrees )C +/- 6.69, respectively. Dual 2.4-mm cryoprobes in our model achieved acute pathological complete coagulative necrosis zone at the center of the ablation zone between the cryoprobes only in the kidney tissue where a mean diameter of the acute complete coagulative necrosis zone was 39.6 mm +/- 0.76 mm. The critical temperature of -20 degrees C was not reached at the midpoint between the probes with the 20-mm spacing arrangement in the lung and liver. These results emphasize the need for individualized organ ablation treatment protocols.