| Objective: the goal of this study was to document the temperature changes and iceball formation of the tip of cryoprobe in air, water and rabbit liver, arteria carotis, and to assess the deactivation of lung cancer cells in vitro and vivo undergone cryotherapy. CT appearance and local changes were to be estimated at different stages after percutaneous lung cancer cryoablation (PLC). A retrospective analysis was made according to CT, positive emission tomography ( PET), lung tissue biopsy and survival rate after cryotherapy.Methods and materials:1. Experimental studies in air and water: The temperature was carefully documented at different part from the tip of cryoprobe carried 4-8 thermocouples. The iceball formation at the tip of probe was observed during cryoablation.2. Deactivation of lung cancer cells in vitro: Small cell lung cancer lines directly underwent cryotherapy. Then, the cryolysis cells were examined in light microscopy (LM). T-lymphocytes(TCs) were obtained from human peripheral blood, dentric cells (DCs) from human bone marrow, and cytotoxic T-lymphocytes(CTLs) from TCs stimulated by DCs which were previously mixed with cryodestroyed lung cancer cells.Experiment 1: Apoptosis of lung cancer cells, 3 groups:(l) TCs, (2)DCs + DCs, (3)CTLs. All groups were mixed with NCI-H446 cells, respectively. Then the cytology and apoptosis of lung cancer cells were observed on LM, electric microscopy (EM) and flow cytometry.Experiment 2: Tumor-Killing activities, 3 groups: (1) TCs, (2) TCs+DCs, (3)CTLs. All groups were mixed with 51Cr-NCI-H446 cells, respectively. Then cpm in every suspension was measured, tumor-killing activities was calculated.3. In vivo experiments: the cryoprobe were inserted into the rabbit liver and lung, and put the probe besides the arteria carotis in a rabbit for general anesthesia. The iceball formation and blood flow were documented during and after cryotherapy.4. Clinical studies: a retrospective review was done in 307 lesions of 237 cases with lung cancer underwent 278 cryosurgeries using local anesthesia with minimal or no sedation guided by computer tomography between Augest 2001 and April 2003. The iceball covered lung mass was measured after cryoablation immediately, and the follow-up of CT scan, positive emission tomography (PET), lung tissue biopsy and survival rate were observed.Results:1. The characteristics of Endocare cryocare system were proved by the experiments in air and water. Rapid supercooling was found at the tip of cryoprobe whether it was in air or in water. The nearer the tip, the more obvious the temperature change. The temperature could be at -130癈 for seconds. Frost formed in air, iceball formed in water and rabbit liver at the front of cryoprobe during cryotherapy. Frost and iceball could be melted rapidly when helium worked.2. Lung cancer cells were destroyed completely after cryoablation in vitro. In CTLs tumor model CTLs stimulated by cryo-induced DCs could result in a significant increase of apoptosis of lung cancel-cells, while there were no obvious apoptosis of lung cancer cells treated by TCs or TCs+DCs alone. Apoptosis cells and apoptosis bodies could be found in CTLs tumor model, while they could not found in other two groups.In CTLs tumor model CTLs could significantly increase tumor-killing activities, while there were no obvious changes in other two groups ,too.3. Clinical experience showed that the efficacy of cryotherapy was closely related to the tumor size and location. Ice formation was well seen as negative Hounsfield units within soft tissue masses less ihan 10 mins after cryoablation. Tumor size and location were independent determinants of ice coverage: 96.7% (N= 124) for masses < 4 cm in diameter, and 79.6% (N= 183) for masses >4 cm(pO.OOOl). Only 25.9% of patients had slight hypertension temporally, and no death happened during cryotherapy. The overall pneumothorax rate was only 29.1%, slight haemoptysis 59. |
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