Experimental And Clinical Study Of Ultrasound-guided Percutaneous Microwave Ablation For Uterine Leiomyoma In Situ

Objective:To investigate the shape,size,and relationship between output energy and ablated effect of microwave ablation in ex vivo muscular tissue and uterine leiomyoma;to observe the sonographic image in the target during ablation and to evaluate the feasibility,safety and effectiveness of ultrasound-guided percutaneous microwave ablation for uterine leiomyoma in situ.Material and methods:Part One:The experimental study of microwave ablation in ex vivo muscular tissue and uterine leiomyoma 1.Microwave ablations were performed using a 2450 MHz microwave generator and radiating mode of continuous wave in ex vivo pig muscular tissues with single antenna or double antennae(inter-antenna distances of 1.5cm) respectively.The output powers were set at 40 W,50 W,60W and 70W,and the ablation time was set at 300s and 600s.The shape,size,and temperature of thermal field were observed.2. Ex vivo pig muscular tissue and uterine leiomyoma ablations were performed at output power of 50W and emission time of 300s respectively.The shape,size, pathology and the sonographic image of the ablation zones were observed.3.The pig muscular tissues ablations were performed at same output power and emission time,and the radiating modes were continuous or intermittent(emitting per 100 seconds intermitting 10 seconds and 20 seconds) respectively.The shape,size, thermal field temperature and the pathology of the ablation zones were evaluated.Part Two:The clinical study of ultrasound-guided percutaneous microwave ablation for uterine leiomyoma in situ 1.Fifteen patients with uterine leiomyoma and ten patients with adenomyosis underwent contrast-enhanced ultrasound(CEUS) one week before operation.1.0ml and 2.4ml SonoVue were used respectively to observe the enhanced pattern of the target.2.The patients with symptomatic uterine leiomyomas were selected as research object.After ultrasound-guided percutaneous biopsies,these patients were treated with microwave ablation for uterine leiomyoma under setting power with one or two antennae.The ultrasound images were stored and the patient's complains were recorded during microwave ablation.The necrosis rate of myomas was assessed by CEUS and CE-MRI.The patients were followed up for one year after the treatment.The complications and side effects were observed,the blood serum estrogen level was examined,and the shrink rate of myoma and uterus were calculated.Resluts:Part one:The shapes of microwave ablation were all elliptical with single antenna in different microwave dosages,and near spherical with double antennae.The ablation volume enlarged with the increase of output power when the time was fixed,but there was no linear relationship.The ablation zone was most near spherical with single or double antennae when the output power was set at 50W.Microwave ablation did not damage the tissues on the needle track.The tissue can not been coagulated when the temperature was less than 58℃lasting 10s.The ablation volume was smaller in ex vivo uterine leiomyoma than pig muscular tissue under the same output power and emission time.No significant difference was observed in the ablation shape and sonographic appearance between ex vivo uterine leiomyoma and pig muscular tissue.There was a thermal leak when the leiomyoma capsule was uncontinuous.With the same output power and the same emission time,No significant difference was observed in the ablation shape,volume,forward distance and thermal field temperature,and the pathologic appearances of the ablated zone were same between continuous wave and intermittent wave.Part two:Uterine leiomyoma and adenomyosis showed different enhancement patterns.The target zone showed the same enhancement pattern with two different doses,however,the peak intensity was lower in 1.0ml SonoVue than in 2.4ml SonoVue.Fifteen leiomyomas in thirteen patients were treated with percutaneous microwave ablation.The pathologic diagnosis of all lesions in pre-ablation was uterine leiomyoma.Seven fibroids were intramural myomas and six were subserous myomas,two were submucous myomas.No serious complication occurred during and after the ablation.All the patients left hospital in three days after the treatment.After the administrations of SonoVue, fifteen fibroids showed no enhancement in the internal of thirteen lesions,and only two lesions had partial enhancement in the periphery.The follow-up ranged from 7 days to 1 year.The volumes of the uterine leiomyomas showed obvious reductions.There was no significant change in the blood serum estrogen level after the treatment.Conclusions:1.The results of ablated muscular tissues using water-cooled implanted microwave is stable and reliable.In different emission time,the ablated shape was the most near spherical with an output power of 50W or 60W.2.The parameters of microwave ablation in ex vivo pig muscular tissues provide technical basis for clinical microwave ablation of uterine leiomyoma.3.With the same output power and same emission time,continuous and intermittent microwave ablation may result in same therapeutic efficacy.4.CEUS is an effective method for the differential diagnosis between uterine leiomyoma and adneomyosis.Use of low dose contrast agent may provide exact information on the differential diagnosis between the two diseases.5.Percutaneous microwave ablation is a safe and effective method for uterine leiomyoma.It is minimally invasive,easy,fast,with no serious complication and less adverse reactions, having no impact on ovarian function,and the patients recover soon after treatment.6.Ultrasound can guide the antenna implantation and monitor the ablation process;CEUS may offer exact information for ablated effect immediately after the treatment.