Clinical Application And Basic Research Of Radiofrequency Ablation In Vertebral Metastases

Objective1.In this study,we studied the safety and effectiveness of posterior decompression surgery and radiofrequency ablation followed by vertebroplasty in spinal metastasis from lung cancer.2.In vivo animal experiments,we explore the safe parameters and safe range of radiofrequency ablation,verify the thermal insulation effect of posterior cortex of vertebral body.Finally,the safety of radiofrequency ablation was verified by in vivo vertebral tumor model.3.COMSOL software was used to establish the simulation model to guide the needle placement in vertebral body before radiofrequency ablation.Methods1.Application of radiofrequency ablation in spinal metastases from lung cancer From July 2008 to November 2012,15 patients with spinal metastases from lung cancer in our hospital were studied retrospectively.All patients underwent posterior laminectomy to relieve the compression of spinal cord,then radiofrequency ablation in the vertebral body,and finally vertebroplasty to enhance the stability of vertebral body.All patients received comprehensive treatment.2.Radiofrequency ablation in vivo swine modelTo explore the safe parameters of radiofrequency ablation in Bama miniature pigs,different radiofrequency ablation parameters were set.The direct and indirect injury area after radiofrequency ablation was evaluated by MRI,HE staining and TUNEL staining method.The model of lumbar vertebral body tumor was made and radiofrequency ablation was carried out in the vertebral body tumor to verify the safety of radiofrequency ablation in vertebral tumors.3.Establishment of radiofrequency ablation simulation modelThe two-dimensional plane cancellous bone and cortical bone were separated by Mimics software to construct a three-dimensional geometric model.The model was imported into the three-dimensional finite element COMSOL software.According to the thermophysical parameters and the mesh division of the geometric model,the finite element simulation model was initially established.Results1.Patients were followed up for 6-56 months,the average operation time was190±50min,and the average blood loss was 336±90 ml.The VAS score was7.86±0.86 before surgery and 3.51±1.32 3 months after surgery,and the pain was significantly improved(t=7.95,P<0.01).Frankel grade of 14 patients was improved by 1 to 2 grades.2.In vivo experiments,the safety parameters of radiofrequency ablation in lumbar vertebrae of Bama miniature pigs were obtained.On the 14 th day,the radiofrequency ablation area of vertebral body could be clearly observed by MRI and HE staining.TUNEL staining showed a large number of apoptotic cells in the radiofrequency ablation area.There was significant difference in the temperature in the spinal canal between the posterior cortex removal and retention groups(P < 0.05).3.The three-dimensional geometric model is constructed by Mimics software.The model is imported into the three-dimensional finite element COMSOL software,and the finite element simulation model is successfully established.The simulation model is verified by the relevant data of in vivo experiment.Conclusion1.Through the indirect decompression of spinal cord through the posterior approach,radiofrequency ablation combined with vertebroplasty,the pain,neurological function and life of the patients were significantly improved.2.In vivo animal experiments,the safety parameters of radiofrequency ablation of lumbar vertebrae in Bama miniature pig were obtained.The effective range of radiofrequency ablation was evaluated by imaging and pathological methods.The safety of radiofrequency ablation was verified by vertebral tumor model.3.COMSOL software was successfully used to build a three-dimensional finite element model,which can guide the needle placement in radiofrequency ablation of vertebral body.