The Heat Distribution Of Radiofrequency Ablation In The Ex Vivo Vertebral Tumor Model

Objective: To inestigate the heat distribution of radiofrequency ablation(RFA) in the ex vivo vertebral tumor modle and heat isolation effect of posterior cortical bone using UniblateTM Rita electrode with diffierent exposed length and diffierent set temperature,preliminary discuss the valid range of RFA treating vertebral tumor lesion and the thermal protection of posterior cortical bone to the spinal cord.Methods: 1. Invetigate the heat distribution of radiofrequency ablation in the ex vivo vertebral tumor modle 10 fresh lumbars excised from adult swines to creat the ex vivo vertebral tumor modle,1cm、2cm exposed length Uniblate TM Rita electrode were plunged into the vertebral with the enterence of one pedicle,75℃、80℃、85℃、90℃、95℃ RFA procedure were applied in each sample,each procedure lasts 15 mins.Set up the temperature measurement points which perpendicular to the electrode along the two sides of electrode,the depth of temperature measurement points are consistent with electrode the valid range of RFA in the ex vivo vertebral tumor modle with diffierent exposed length electrode and diffierent set temperature. 2. Investigate the heat isolation effect of posterior cortical bone in the ex vivo vertebral tumor modle.20 fresh lumbars excised from adult swine were divided into intact posterior cortical bone group(intact group) and defect posterior cortical bone group(defect group)randomly,creating the intact posterior cortical bone tumor model and defect posterior cortical bone tumor model respectively.Apply the RFA procedure using UniblateTM Rita electrode with the enterence of one pedicle in 2cm exposed length and 95℃ set temperature,each procedure lasts 15 mins.Results: 1. The valid range of RFA in the ex vivo vertebral tumor modle:with 1cm exposed length elctreode,set temperature 75℃、80℃、85℃、90℃、95℃,all the radiuses of 50 ℃ RFA range in the ex vivo vertebral tumor modle didn’t exceed 5mm,each radius is 3.80±0.79 mm,4.1±0.74 mm,4.3±0.82 mm,4.4±0.84 mm,4.5±0.71 mm.With 2cm exposed length elctreode,set temperature 75℃、80℃、85℃、90℃、95℃,the radiuses of 50℃ RFA range in the ex vivo vertebral tumor modle are 6.4±0.52 mm,7.4±0.71 mm,8.0±0.67 mm,8.2±0.63 mm,8.3±0.68 mm. 2. The effectiveness of RFA treating vertebral tumor:When the RFA set temperature is 75℃,there is no group of the temperature in the tumor model reached 43℃.When the RFA set temperature is 85℃,the temperature in the tumor model of the 2cm electrode length group reached 43℃,on the contrary of 1cm electrode length group.When the RFA set temperature is 95℃,all groups temperature in the tumor model reached 43℃. 3. The heat isolation effect of posterior cortical bone in RFA procedure: the anterior and posterior temperature of posterior cortical bone in the intact group are 50.28±4.21℃、38.26±4.47℃,the temperatures have statistically difference(P=0);The anterior and posterior temperature of posterior cortical bone in the defect group are 51.07±4.23 ℃,49.27±3.84 ℃,the temperatures have no statistically difference(P=0.16).Conclusions: 1. With 1cm exposed length UniblateTMRita elctreode,set temperature 75℃、80℃、85℃、90℃、95℃,all the radiuses of 50℃ RFA range in the ex vivo vertebral tumor modle didn’t exceed 5mm. 2. With 2cm exposed length UniblateTMRita elctreode,set temperature 75℃、80℃、85℃、90℃、95℃,the bigest radius of 50℃ RFA range in the ex vivo vertebral tumor modle is 8.3±0.68 mm. 3. With 2cm exposed length elctreode,set temperature 95 ℃,The anterior and posterior temperature of posterior cortical bone in the intact group have statistically difference(P=0),The anterior and posterior temperature of posterior cortical bone in the defect group don’t have statistically difference.