New-type Of Water-cooled 2450MHz Microwave Ablation Antennae: Experimental And Preliminary Clinical Application Study Of Three-dimensional Thermal Field

Objective:1.Based on the need of preoperative planning for intelligent microwave ablation instrument,study the computer simulation method of three-dimensional thermal field distribution of 2450MHz new-type of water-cooled microwave ablation antennae in microwave phantom, and to establish the computer-simulated three-dimensional thermal field under different power and time.2.Correct the thermal field based on the ablated lesions and temperature curves in vitro porcine livers.3.Then correct the vivo liver thermal field based on ablated lesions and temperature curves in clinical cases.The thermal field model is applied to the thermal field planning of the intelligent microwave instrument,and the reliability of the three-dimensional thermal field applied to the preoperative planning is tested by the effect of clinical practical ablation.Materials and Methods:1.Microwave phantom experimental study:According to the Pennes bio-heat transfer formulation,precisely arrangement 22 points whose temperatures measured by thermal couple in microwave phantom,using the new-type of water-cooled microwave antennae (tip 11 mm) to ablate.According to the slopes of initial temperature curves and temperature conduction, the distributions of special absorption rate (SAR) of 2450MHz microwave in phantom were divided into two quadrants(Z>0 and Z<0). Adopt exponential decay in r axis and three-order polynomial in z direction.Three-dimensional thermal fields were simulated by finite element method by computer in five different energy outputs (40W600S,45W600S,50W600S,55W600S,60W600S).2.vitro experimental study: Microwave ablation were performed in fresh vitro porcine livers with different energy outputs by a single 2450MHz microwave ablation antennae,temperature measuring antennae paralel with microwave ablated antennae implant into vitro porcine liver to measure temperature curves.The results of ablation zone’size and temperature were recorded.20 times ablation experiments with 80 points temperature curves were performed in 12 fresh vitro porcine livers,and 4 points temperature detection performed in each energy outputs group respectively,each point was repeated 4 times.Analyze the data,verificated and calibrated the three-dimensional thermal fields of phantom experiments repeatedly.3.Clinical Study:Firstly,the parameters of blood infusion rate of human liver tumor were brought into the finite element analysis software,and the three-dimensional thermal field model of microwave ablation liver tumor was obtained.Then retrospective analysis 97 cases of patients with a total of 129 lesions of the clinical practical microwave ablation range,statistical analysis the microwave ablation range of 50W power with different time and selected 12 cases patients,no obvious vascular influence, using single needle microwave antenna(KY2450B) with 50W microwave power to ablate.The distance between temperature measured needling and microwave antenna is 5mm or 10mm,recording the temperature curve at the same time.Compare the three dimensional thermal field with clinical measured temperature curves and the coagulation range,verificating and calibrating the computer simulation three dimensional thermal field of microwave ablate liver tumors.Finally the corrected three-dimensional thermal field model is applied in preoperative thermal field planning,clinical microwave ablation in accordance with the planning,through the ablation efficacy to inspect the reliability of three-dimensional thermal field model.Results:1.Microwave phantom experimental study:(1)The distributions of SAR in five energy conditions were obtained through phantom experiments,that had no linear relationship with powers. (2)By using the finite element method,we establish five energy conditions’ computer-simulated three-dimensional thermal field model of 2450MHz new-type of water-cooled microwave ablation antennae. 2.vitro experimental study:we found that measurement temperature curves of the actual vitro liver tissue have a better consistency with the temperature curve of computer-simulated three-dimensional thermal field.Moreover,the shapes and scope of ablation also have a better consistency with the three-dimensional thermal field.3.Clinical study:Solidification range of single microwave antenna measured by contrast enhanced ultrasound were obtained.At the same time,in clinical temperature measurement,the temperature rising curve is obtained. Through the clinical practice of ablation range and temperature rising curve to verificate and calibrate the three-dimensional thermal field model,the three-dimensional thermal field model is applied to preoperative thermal field planning.The success rate of the preoperative thermal field planning was 92.8% (13/14),the reliability of the three-dimensional thermal field model for the preoperative planning is verified.Conclusions:1.Computer-simulated three-dimensonal thermal fields of 2450 MHz new-type of water-cooled microwave ablation antennae in the phantom experiment were accurate and reliable.2.The temperature curves and microwave ablation scope of vitro porcine livers experiments have a better consistency with computer-simulated three dimensonal thermal fields.3.Through the clinical practice of ablation range and temperature rising curve to verificate and calibrate the three-dimensional thermal field mode is more consistent with the clinical situation,the corrected three-dimensonal thermal fields model can meet the clinical microwave ablation of thermal field planning’ requirement.