Finite-element Analysis And Experimental Study For Multiple Electrodesbipolar Endometrial Radio-frequency Ablation

Objective To simulate the temperature distribution of multiple electrode bipolar RFglobal endometrial ablation by the finite element method. This thermotherapy mightimprove the treatment safety and effectiveness of endometrial ablation. To explore therelationship between lesion and radiofrequency power, some experiments of fresh steakswere done. It might provide helpful references for clinical applications for multiple probesendometrial radio-frequency ablationMethods With three common sizes of the uterine cavity as the research objects andaccording to the bio-heat transfer equation, three finite element models were established toanalyze the changes of peak temperatures, lesion area and lesion depth in different sizes ofuterine cavity under different radio-frequency voltages. Fresh steaks, which size isapproximately150*100*15mm, were selected to ablate with multiple electrodes, and theablation time were set250seconds by the RF machine made by Cardea Medsystems(Tianjin) Co. Ltd. Take a set of experiments to measure the maximum temperature and theminimum temperature, putting thermocouples around the electrodes and the center. Observethe lesion region, analyze the rule of lesion changes with RF power, and compare thedifferences between calculated temperature values and the measured ones.ResultsSimulations showed that:Under the same voltage, as the size of uterine cavitybecame greater, maximum temperature changed small, minimum temperature and lesiondepth became lower, and lesion area was larger. In the same size of uterine cavity, as thepower became higher, maximum temperature was higher, and minimum changed small,lesion region was larger and lesion depth was deeper.Experimental results show that:Imposing different RF power to electrodes, it can find that lesion region is similar to thetriangular area bounded by the three pairs of electrodes. In the prophase of RFA, thetemperature of point E rose rapidly, and the temperature of point O increased slowly. In themedium-term of RFA, the temperature of point E remained stable, and the temperature ofpoint O rise accelerating. In the later stage of RFA, the temperature of point E declinedrapidly, and the temperature of point O increased slowly.Conclusions Uterine cavity size and radio-frequency voltage should be considered inendometrial ablation.Based on the FEM analysis and calculation, it is possible to reflectdistribution and variation of temperature field in endometrium radiofrequency ablation,which could add more rationality, effectiveness and safe to clinic.