title: Radiofrequency tissue ablation: increased lesion diameter with a perfusion electrode.
abstract: OBJECTIVE
  We sought to induce large zones of coagulation necrosis using radiofrequency (RF) with perfusion electrodes and to define optimal parameters for this system.
  
  
  METHODS
  We developed RF electrodes with internal cannulas to enable tip perfusion. Lesions were created with monopolar RF in ex vivo and in vivo liver and muscle tissue with and without perfusion of the electrode tip using 0 degree C saline. In separate experiments, wattage, current, procedure duration, tip exposure, and perfused tip temperatures were studied.
  
  
  RESULTS
  In ex vivo liver tissue, a maximum lesion diameter of 3.1 cm without charring occurred with perfusion at 12 min and 50 W. In in vivo liver tissue with perfusion (tip temperature = 25-35 degrees C) and a 3-cm tip exposure, 80 W were deposited in muscle tissue and 65 W in liver tissue for 12 min without inducing charring. Lesion diameters were 4.5 cm and 2.4 cm, respectively. By comparison, without perfusion a maximum of 20 W could be deposited into either tissue type, resulting in 1.8-cm muscle lesions and 1.2-cm liver lesions. Tip temperatures between 45 degrees C and 55 degrees C resulted in charring. Smaller but predictable lesion diameters were created with a lower power, a shorter tip exposure, or both. Of all the parameters, diameter correlated best with the current applied.
  
  
  CONCLUSIONS
  Perfusion of RF electrodes with chilled saline allows for increased power deposition without tissue charring, increasing the volume of coagulation necrosis created with a single electrode insertion. Perfusion electrodes therefore might decrease the number of probe insertions required for percutaneous tumor ablation therapy or allow for the treatment of larger lesions.
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA.
authors.forename: S N
authors.initials: SN
authors.lastname: Goldberg
authors.forename: G S
authors.initials: GS
authors.lastname: Gazelle
authors.forename: L
authors.initials: L
authors.lastname: Solbiati
authors.forename: W J
authors.initials: WJ
authors.lastname: Rittman
authors.forename: P R
authors.initials: PR
authors.lastname: Mueller
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation*; D002417:Cattle; D004566:Electrodes; D066298:In Vitro Techniques; D008099:Liver / Q000473:pathology / Q000601:surgery; D018482:Muscle, Skeletal / Q000473:pathology / Q000601:surgery; D009336:Necrosis; D013552:Swine; D013696:Temperature