title: Multiple-electrode radiofrequency ablation of hepatic malignancies: initial clinical experience.
abstract: OBJECTIVE
  The objective of our study was to retrospectively analyze our initial clinical experience with percutaneous multiple-electrode radiofrequency ablation and evaluate its safety and efficacy for treating hepatic malignancies.
  
  
  METHODS
  Thirty-eight malignant hepatic tumors (mean diameter, 2.7 cm; range, 0.7-10.0 cm) in 23 patients (12 men and 11 women; mean age, 65 years; range, 40-84 years) were treated in 26 radiofrequency ablation sessions with an impedance-based multiple-electrode system. One, two, or three (mean, 2.4) 17-gauge electrodes were placed, and tumors were ablated using a combination of CT and sonography for guidance and monitoring. Electrodes were placed in close proximity (mean spacing: two electrodes, 1.0 cm; three electrodes, 1.4 cm) to treat large tumors or were used independently to treat several tumors simultaneously. Contrast-enhanced CT scans were obtained immediately after ablation to determine technical success and evaluate for complications. Follow-up CT scans at 1, 3, 6, 9, and 12 months (mean, 4 months) after ablation were obtained to assess for tumor progression and new metastases.
  
  
  RESULTS
  Local control was achieved in 37 of 38 tumors, 34 of which were treated in one session. Ablations created with closely spaced electrodes had a mean diameter of 4.9 cm. The total ablation time was reduced by approximately 54% compared with an equivalent number of ablations performed with a single-electrode system (1,014 vs 2,196 minutes). Three complications occurred: one death from a presumed postprocedure pulmonary embolus, one pneumothorax, and one asymptomatic perihepatic hemorrhage.
  
  
  CONCLUSIONS
  Multiple-electrode radiofrequency ablation appears to be a safe and effective means of achieving local control in large or multiple hepatic malignancies at short-term follow-up.
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin, Madison, WI, USA.
authors.forename: Paul F
authors.initials: PF
authors.lastname: Laeseke
authors.forename: Tina M
authors.initials: TM
authors.lastname: Frey
authors.forename: Chris L
authors.initials: CL
authors.lastname: Brace
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Sampson
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Winter
authors.forename: Jan R
authors.initials: JR
authors.lastname: Ketzler
authors.forename: Fred T
authors.initials: FT
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging / Q000601:surgery*; D017115:Catheter Ablation / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods*; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D016896:Treatment Outcome; D014463:Ultrasonography