On freeze-thaw sequence of vital organ of assuming the cryoablation for malignant lung tumors by using cryoprobe as heat source.

Regarding cryoablation for the malignant lung tumors, multiple trials of the freeze-thaw process have been made, and we considered it necessary to view and analyze the freeze-thaw process as a freeze-thaw sequence. We caused the sequence in a porcine lung in vivo by using an acicular, cylindrical stainless-steel probe as the heat source for the freeze-thaw sequence and cooling to -150 °C with super high-pressure argon gas by causing the Joule-Thomson effect phenomenon at the tip of the probe. In this experiment, we examined the sequence by measuring the temperature and using the isothermal curve and the freezing function. As a result, it was demonstrated that the freezing characteristics considerably differed in the first sequence and the second sequence from those of non-aerated organs such as liver and kidney. In our experiments on porcine lung, thermal properties were considered to change as the bleeding caused by the first thawing infiltrated in the lung parenchyma, and it was confirmed that the frozen area in the second cycle was dramatically enlarged as compared with the first cycle (when a similar sequence is continuously repeated, we say it as cycle). This paper provides these details.