title: Bipolar radiofrequency ablation of liver metastases during laparotomy. First clinical experiences with a new multipolar ablation concept.
abstract: OBJECTIVE
  Radiofrequency ablation (RFA) is a promising method for local treatment of liver malignancies. Currently available systems for radiofrequency ablation use monopolar current, which carries the risk of uncontrolled electrical current paths, collateral damages and limited effectiveness. To overcome this problem, we used a newly developed internally cooled bipolar application system in patients with irresectable liver metastases undergoing laparotomy. The aim of this study was to clinically evaluate the safety, feasibility and effectiveness of this new system with a novel multipolar application concept.
  
  
  METHODS
  Patients with a maximum of five liver metastases having a maximum diameter of 5 cm underwent laparotomy and abdominal exploration to control resectability. In cases of irresectability, RFA with the newly developed bipolar application system was performed. Treatment was carried out under ultrasound guidance. Depending on tumour size, shape and location, up to three applicators were simultaneously inserted in or closely around the tumour, never exceeding a maximum probe distance of 3 cm. In the multipolar ablation concept, the current runs alternating between all possible pairs of consecutively activated electrodes with up to 15 possible electrode combinations. Post-operative follow-up was evaluated by CT or MRI controls 24-48 h after RFA and every 3 months.
  
  
  RESULTS
  In a total of six patients (four male, two female; 61-68 years), ten metastases (1.0-5.5 cm) were treated with a total of 14 RF applications. In four metastases three probes were used, and in another four and two metastases, two and one probes were used, respectively. During a mean ablation time of 18.8 min (10-31), a mean energy of 48.8 kJ (12-116) for each metastases was applied. No procedure-related complications occurred. The patients were released from the hospital between 7 and 12 days post-intervention (median 9 days). The post-interventional control showed complete tumour ablation in all cases.
  
  
  CONCLUSIONS
  Bipolar radiofrequency using the novel multipolar ablation concept permits a safe and effective therapy for the induction of large volumes of coagulation in the local treatment of liver metastases.
authors.affiliation: Department of General, Vascular and Thoracic Surgery, Charité, University Medicine Berlin, Campus Benjamin Franklin, Berlin, Germany. joerg-peter.ritz@charite.de
authors.forename: Joerg-Peter
authors.initials: JP
authors.lastname: Ritz
authors.forename: Kai S
authors.initials: KS
authors.lastname: Lehmann
authors.forename: Christoph
authors.initials: C
authors.lastname: Reissfelder
authors.forename: Thomas
authors.initials: T
authors.lastname: Albrecht
authors.forename: Bernd
authors.initials: B
authors.lastname: Frericks
authors.forename: Urte
authors.initials: U
authors.lastname: Zurbuchen
authors.forename: Heinz J
authors.initials: HJ
authors.lastname: Buhr
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000556:secondary* / Q000601:surgery; D000368:Aged; D017115:Catheter Ablation / Q000379:methods*; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007813:Laparotomy / Q000379:methods*; D008113:Liver Neoplasms / Q000401:mortality / Q000556:secondary* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D009367:Neoplasm Staging; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D015996:Survival Rate; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D018608:Ultrasonography, Doppler