Experimental Study On Cryoablation For Pig Liver And The Treatment Of Subcapsular Liver Tumors With Accu Target

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The experimental study on cryoablation for pig liver with Accu targetObjective:The small vivo pig liver was used as the experimental model,to explore the difference between the size of ice-ball shown in the CT scan images and the actual size in the process of CT-guided cryoablation with Accu-target,compare the difference between 1 and 2 freeze-thaw cycles.Methods: A total of 4 miniature bama pigs(25-30kg)were randomly divided into two groups.Using intramuscular injection of su-mian-xin II mixture(0.1ml/kg)and diazepam(5mg)to induced general anesthesia of the miniature pigs,the superficial intravenous needle was fixed firmly in the ear vein,and propofol was injected intravenously to maintain anesthesia.Right costal margin incision was taken to expose the liver,and 2 target ablation areas were selected from the thicker liver lobe of each pig liver,and cryoablation was performed by placing a cryoprobe in the appropriate position.The group A performed the procedure of 1 freeze-thaw cycle(10-3 minutes),while the group B performed the procedure of 2 freeze-thaw cycles(10-3 minutes).At the end of the freeze cycle in each target area,pin marks were randomly placed at the ice-ball boundary on the liver surface.CT scan was performed immediately after the end of freeze cycle.After scanning,Multi-planar reconstruction(MPR)was performed to reconstruct the maximum width and diameter of the ice-ball and parallel planes of the cryoprobe and the pin on the liver surface.The distance between the pin and the cryoprobe was measured and recorded.The maximum diameter of the ice-ball shown in the CT scan images and the distance between the cryoprobe and the parallel layer of the pin and the low-density shadow edge were measured on the MPR image.Miniature pigs were sacrificed after the procedure,liver samples of the target area were taken out and fixed in 10% formaldehyde solution for 48 hours.The specimen was cut vertically along the needle track of the cryoprobe,and the maximum width of the ice-ball was selected.HE and TUNEL staining were performed on paraffin-embedded sections.After the staining was completed,the pathological changes were observed,and the distance between the boundaries of the inactive areas and the needle tract was measured in TUNEL staining with the Toup View microscope image measurement software.Results: 1.There was no significant difference between the cryoprobe and the low-density shadow edge and the distance between the cryoprobe and the pin(p=0.732,95%CI difference number was-0.09~0.07).2.The maximum width of the ice-ball after the procedure of 1 cycle is 27.6± 0.9mm,while the maximum width of the ice-ball after the procedure of 2 cycles is 31.4 ±0.5mm,(p<0.01).After repeated freeze-thaw cycle,the diameter of the ice-ball extends outward for about 3mm.3.The TUNEL staining showed that the area with a radius of only 8.4 ±0.2mm was the actual necrotic area in the ice-ball after the procedure of 1 cycle,and the boundary difference between the edge of ice-ball and the actual necrotic area was 5.6±0.5mm.After repeated freeze-thaw cycle,the area of 12.6±0.4mm in the ice-ball coverage was the actual necrotic area,and the boundary difference between the edge of the ice-ball and the actual necrotic area was 3.2±0.2mm.Conclusion: 1.The low-density shadow area shown by CT scan during cryoablation can accurately reflect the actual ice-ball formation range.2.The formation range of the ice-ball of 2 cycles procedure on10-3min freeze-thaw mode is larger than 1 cycle with the cryoablation equipment of Accu target.In addition,the actual necrotic area was significantly larger and the safe ablation boundary was smaller.Part ? Percutaneous cryoablation of subcapsular liver tumors with Accu targetObjectives: This study aims to evaluate the safety and efficacy of the treatment of subcapsular liver tumors with percutaneous cryoablation performed using the domestic cryoablation device(Accu target).Patients and Methods: A total of 44 patients with subcapsular(<1 cm form the liver edge)liver tumors(50 lesions),who were treated with CT-guided percutaneous cryoablation in the Department of Interventional Radiology of our hospital between July 1,2016 and September 1,2018,were retrospectively enrolled.All patients were followed up with MRI and laboratory examination.Complete ablation rate,local tumor progression(LTP)and treatment-related complications were evaluated.Furthermore,intraoperative and postoperative pain was measured using the visual analog scale(VAS),and laboratory findings were compared before and after the procedure.Results: All patients successfully completed the treatment.The mean follow-up period was 12.8 months(range: 3–27 months),and the complete ablation rate was 96%(48/50).Furthermore,local tumor progression occurred in nine patients(18%),and the 6-,12-and 18-month cumulative LTP rates were 4.0%,8.2% and 20.5%,respectively.Two patients with multiple systemic metastases died during the follow-up period.In addition,two patients(4.5%,2/44)developed major complications,and the minor complication rate was 27.2%(12/44).The mean VAS score during the operation was 1.65 points(range: 1-3 points).Furthermore,transient changes in biochemical and hematologic markers were observed.Conclusion: Cryoablation using the novel device is safe and effective in the treatment of this cohort of patients with subcapsular liver tumors.The procedure is simple,and the patients suffer less pain.