Clinical Application of Protocol for Ultrasound-guided Radiofrequency Ablation on Large Hepatic Tumors

陈敏华  杨 薇
北京肿瘤医院超声科 100036
E-mail: minhuachen@vip.sina.com
资金项目：首都医学发展科研基金项目（ZD199909）
Minhua Chen, Wei Yang
Department of Ultrasound, Clinical Oncology Institute, Peking University, Beijing 100036, China <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

Abstract

Objective: To develop a protocol for ultrasound-guided percutaneous radiofrequency ablation (RFA) of hepatic tumors larger than 3.5 cm in diameter, and to evaluate its role and safety in ablation treatment. Methods  The high local recurrence was observed in hepatic tumors larger than 3.5 cm. So we designed a preoperative protocol to cover and ablate tumors in different sizes with 5.0 cm ablation sphere. Mathematical: analysis was performed to generate the preoperative protocol which included the least ablation (sphere) number and the optimal overlapping mode and procedure for adequately ablating a large and spherical target lesion. The target ablation volume consisted of a tumor plus a 0.5 ～ 1.0 cm tumor-free margin. The protocol was predicted as follows: 3 ablations are given for tumors in diameter of 3.6 to 3.9 cm by using a centric three-spot overlapping method; 4 ablations for tumors of 4.0 to 4.3 cm using the regular tetrahedron mode; 5 to 8 ablations for tumors of 4.4 to 5.6 cm using the regular 3 ～ 6 prism modes; and 12 ablations for tumors of 5.7 to 6.5 cm using the regular dodecahedron mode (three-segment overlapping ablations). The operation method for electrode placement was also described. Based on this mathematical protocol, 141 patients with 162 hepatic tumors [(4.79 + 0.96) cm in diameter, ranging from 3.6 ～ 7.7 cm] were enrolled and treated. Eighty-three patients had 93 primary and 58 had 69 metastatic hepatic tumors. Results: Totally 712 ablations (electrode placements) were performed in 162 tumors. The tumor complete necrosis rate was 90.1 % (146/162), the local recurrence rate 21.0 % (34/162). Mean local recurrence-free survival was 17.3 months. Twenty-six patients had received 39 retreatments for the local recurrence (18 received one, and 8 received two or three). Seven major complications (4.9 %)   were found in the 141 cases. Of them, only one patient who suffered from colon perforation one week after RFA treatment required surgical intervention. Conclusions A theoretic basis and clinical guidance in RFA of hepatic tumors larger than 3.5 cm might be provided. Treatment results indicated that the protocol might probably be used to improve complete necrosis rate and be an effective and feasible way in ablation therapy.
　　Key words：Ultrasonography; Radiofrequency Ablation (RFA), Interventional; Liver neoplasm; Mathematical model