title: Large-volume tissue ablation with radio frequency by using a clustered, internally cooled electrode technique: laboratory and clinical experience in liver metastases.
abstract: OBJECTIVE
  To evaluate whether coagulation necrosis achievable with radio-frequency (RF) ablation can be increased by using a cluster of closely spaced electrodes.
  
  
  METHODS
  RF was applied to ex vivo liver (n = 68), in vivo liver (n = 12), and in vivo muscle (n = 15) by using a cluster array of three separate internally cooled electrodes spaced 0.5 cm apart. The diameter of coagulation necrosis achieved with optimal RF deposition (1,400-2,150 peak mA) for 5-60 minutes of RF application was determined for electrode tip lengths of 1.5-3.0 cm and compared with that obtained by using a single electrode and otherwise similar technique. Ten patients with solitary intrahepatic colorectal metastases were also treated by using cluster electrode RF ablation.
  
  
  RESULTS
  In ex vivo liver, simultaneous RF application to electrode clusters for 15, 30, and 45 minutes produced 4.7 cm +/- 0.1, 6.2 cm +/- 0.1, and 7.0 cm +/- 0.2 of coagulation necrosis, respectively. In in vivo liver and muscle, RF applied to electrode clusters for 12 minutes yielded 3.1 cm +/- 0.2 and 7.6 cm +/- 0.4 of coagulation, respectively. RF application to a single electrode produced maximal coagulation of 2.9 cm in ex vivo liver, 1.8 cm in in vivo liver, and 4.3 cm in muscle (P < .01, all tissues). In colorectal metastases, a single 12-15-minute application of RF to an electrode cluster induced 4.5-7.0 cm of coagulation necrosis.
  
  
  CONCLUSIONS
  Simultaneous RF application to a cluster of three closely spaced internally cooled electrodes enables a larger volume of coagulation in ex vivo liver, in vivo tissues, and hepatic colorectal metastases than previously reported.
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, USA.
authors.forename: S N
authors.initials: SN
authors.lastname: Goldberg
authors.forename: L
authors.initials: L
authors.lastname: Solbiati
authors.forename: P F
authors.initials: PF
authors.lastname: Hahn
authors.forename: E
authors.initials: E
authors.lastname: Cosman
authors.forename: J E
authors.initials: JE
authors.lastname: Conrad
authors.forename: R
authors.initials: R
authors.lastname: Fogle
authors.forename: G S
authors.initials: GS
authors.lastname: Gazelle
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation* / Q000379:methods*; D002417:Cattle; D015179:Colorectal Neoplasms / Q000473:pathology; D004566:Electrodes; D006801:Humans; D008099:Liver / Q000601:surgery; D008113:Liver Neoplasms / Q000556:secondary* / Q000601:surgery*; D018482:Muscle, Skeletal / Q000601:surgery; D013552:Swine