Microwave, Radiofrequency And Laser Ablation In Vitro Pig Thyroid Contrast Experiment Research

Background:Ablative treatments such as microwave ablation, radiofrequency ablation, laser ablation are gaining increasing attention as an alternative to standard surgical therapies. Individualized principles to be followed in the clinical treatment require clinical physicians to select the appropriate treatmen according to the nodal location, size, etc. But the current guidelines for selection of means for thermal ablation of thyroid nodule is still no uniform standard, there is no literature reported in the contrastive study of the three methods.Objective：To evaluate the safety, effectiveness and stability of the three thermal ablation and to compare their respective advantages and disadvantages for benign thyroid nodules,Thus to provide preliminary guidelines for selection of melting means thinking and help clinicians choose the most suitable treatment for patients.Methods:Different duration time and power was used in the ablation of fresh in vitro pig thyroid in three groups:microwave ablation group, radiofrequency ablation group and laser ablation group. The microwave ablation group was tested by Nanjing kangyou KY-2000microwave therapy system. Duration time was set to1min,2min,3min and4min when power was fixed to20W. Power was set to5W,10W,15W,20W,25W,30W when duration time was fixed to4min. The radiofrequency ablation group was tested by radio frequency ablation machine manufactured by Celon AG Corporation in Germany. The power was set to5W,10W,15W,20W and25W in the ablation. The laser ablation group was tested by using ECHO-LASER integrated therapy system. Energy was set to600J,900J,1200J,1500J and1800J when power was fixed to3W. Power was set to2W,3W,4W,5W,6W and7W when energy was fixed to1200J. Real time temperature at the centre of the target was recorded in three groups:20W5min in microwave ablation group,5W in radio frequency group and3W1200J in laser ablation group. The shape, color and carbonization of the ablation zone were observed at the dissection after ablation. Maximum long diameter, short diameter and thick diameter were recorded. A histological examination of the ablation zone was also carried on after ablation。 Result:Hyper echoic zone cased by gas was observed by real time ultrasound at the tip of the electrode or optical fiber when ablation started. As the ablation carried on, the hyper echoic zone enlarged. The size of the ablation zone varied at the microwave group by different dose of power used when duration time was fixed to4min (P<0.05). The size of the ablation zone enlarged as the duration time extended when power was fixed to20W (P<0.05). Within the radiofrequency ablation group, there was no significant difference at the size of the ablation zone (P>0.05). When power was fixed to3W, the size of the ablation zone was significantly different as different energy was used within the laser ablation group (P<0.05), representing an enlargement of the ablation zone along with the enlarged energy. The size of the ablation zone enlarged as power was enlarged when energy was fixed to1200J (P<0.05). The size of the ablation zone was significantly different between three groups of which the parameters were conventionally used in clinical application:20W5min in microwave ablation group,5W in radio frequency group and3W1200J in laser ablation group. The size was larger at the laser ablation group compared with the radiofrequency group (P<0.05), and even larger at the microwave ablation group compared with the laser ablation group (P<0.05). Dissection after the ablation showed an oval shape of the ablation zone, with a gray white appearance. Clear boundary was found at the ablation zone. Within the ablation zone the tissue was even harder. The tissue within the ablation zone had a homogenous appearance in the radiofrequency group and the microwave group, while gasification cavity and carbonization were found at the centre of the ablation zone in laser ablation group. Temperature increased more quickly in radiofrequency ablation group and microwave ablation group compared to laser ablation group, showing a steeper temperature curve.Conclusion:Microwave, radiofrequency and laser ablation three thermal ablation used in the treatment of thyroid nodule is feasible.The same kind of ablation method under different power and time melting range is different, different melting range and melting temperature melting method is different. So in the future on the choice of thyroid nodule ablation means comprehensive consideration, according to the actual situation of lesion for patients to choose one of the most reasonable treatment. Is just an experiment research, this study is only for the clinical treatment of thyroid nodule selection provides a preliminary idea, remains to be the clinical application of large sample research for unified treatment standards and specifications.