Experimental And Preliminary Clinical Application Study Of Microwave Ablation With Cooled-tip Electrode On Spleen Under Ultrasound Guidance

Objective Based on the research of congestive splenomegaly of pigs treated by ultrasound-guided microwave ablation with cooled-tip electrode, explored the ablation power and safety, provide evidences for microwave ablation on splenomegaly、hypersplenism and spleen ingury.Materials and methods:1.Established six mini pigs’ congestive splenomegaly model, ligated their splenic vein and major tributaries. Measured the thickness and width of the spleen befor and after the ligation.2.Experimental study of microwave ablation with cooled-tip electrode on minor spleen ingury. Established mini pigs’model, choose 18 points on 6 pigs, three on each. Conservative treatment group (3 points):local pressure dressing, intravenous reptilase one unit, observed 6 h.The group of microwave ablation:inserted the needle into the tissue of hemorrhage under real-time ultrasound-guidance. Open the microwave apparatus and use its microwave coagulation therapy, choose 70 W/600 s and 80 W/600 s of ablation on 6 points each, and observed 6 h after surgery.3.Experimental study of microwave ablation with cooled-tip electrode on splenomegaly. Establish splenomegaly model of 6 mini pigs, then applied 2450 MHz microwave ablation with cooled-tip electrode (3 points on each spleen, a total of 18 points), power output was set for three groups:60W/600s,70 W/600s, and 80 W/600s, at the same time record temperature; observed local changes in ablation zone, measured coagulation length, width, and calculate the volume for statistical analysis. 4.Experimental study of microwave ablation with cooled-tip electrode on clinic.4 patients was chosen, in which splenomegaly, hypersplenism 3 cases and spleen mass 1 case. The 3 cases were given ultrasound-guided microwave ablation, ablation power of 80W, ablation time was 20-30 minutes. One cases of splenic tumors at first was done puncture biopsy, then gave microwave ablation, ablation power was 80W, ablation time was 15 minutes.Results:1.before splenic vein ligation,6 mini pigs’spleen average thickness was 1.65±0.10cm and average width was 6.57±0.16cm. after ligation, thickness and width were significantly increased, thickness was 2.63±0.12cm, width was 8.52±0.17cm, it has significant statistical differences (p<0.05).2.ultrasound examination can clearly shows the bleeding after splenic rupture, hematoma of the spleen and microwave ablation therapy, hemostasis effect of microwave ablation group was exact, and the coagulation lesions were ellipsoid.70 W-600s group solidified lesion’s length (4.88±0.16) cm, width (1.85±0.11) cm; 80 W-600s group solidified lesion’s length (5.86±0.24) cm, width (2.47± 0.17) cm; the difference was statistically significant (P<0.05), the length and width of 80 W group increase more significantly than 70 W group, and length’s increase was slightly larger than the width. Microwave ablation group had been observed for 6 h, no increase of Peritoneal cavity free fluid was seen, vital signs were stable. The distance between splenic capsule rupture place and microwave needle inserting place was 4～12 mm, at an average of 8 mm, solidified lesions were successfully covered the spleen laceration. Conservative treatment group shows the spleen hematoma gradually increased with increasing intraperitoneal free fluid, shock had gradually increased.3.Different power of the microwave ablation made the same shape of the spleen, which was ellipsoid, and the solidification zone was reddish brown, with drying surface; and without active bleeding after the needle beeing taken out, from ablation center outwards, the tissue were carbonized tissue, ablation solidification tissue, hyperemia tissue and normal tissue, which were shown differences in pathology. In the experiments ablation scales(maximum length, diameter, wide diameter and volume) and temperatures were collected.4.Gave the 4 patients’group liquid diet in 2Hrs after operation, no fever, abdominal pain and other symptoms, and the blood amylase, urine amylase results were within the normal range. Recheck CBC showed:WBC and platelet counts were significantly higher, and got back to the normal in 10d, and in the subsequent month follow-up no abnormal drop of WBC and platelet counts in peripheral blood was found.Conclusion:1. It is reliable to establish splenomegaly model by ligation of splenic vein and its major tributaries, which basically meet the requirement of microwave ablation on treating splenomegaly.2. The shape of microwave ablation tissue was elliptical.3. With the power increased, the volume of ablation lesions was gradually increased. 4.Microwave ablation was done on the spleen, the tissue was changed, from ablation center outwards, the tissue were carbonized tissue, ablation solidification tissue, hyperemia tissue and normal tissue.5 it is safe and feasible that microwave ablation was used to treat splenomegaly, hypersplenism and splenic mass. This technology is expected to become a new, safe and effective minimally invasive treatment for splenomegaly, hypersplenism and splenic mass.6 patients can be well tolerated without obvious abdominal pain, fever, infection and other complications.7. Special imaging and pathology changes after Microwave ablation, can be used as an important indicator for the clinical efficacy and follow-up.8 This study still need to be supported by a large number of samples, multi-center, unified standards of evidence-based medical researches, to regulate the indications, contraindications of microwave ablation to treat splenomegaly, hypersplenism, at the same time, possible complications were needed to be observed, and evaluate its long-term effect objectively through a long-term follow-up observation.