title: Minimally invasive treatment of renal cell carcinoma: comparison of 4 different monopolar radiofrequency devices.
abstract: OBJECTIVE
  Radiofrequency Ablation is an investigational treatment option for RCC. The aim of our study was to test the ablation algorithms of four different RF systems in a standardized ex vivo perfused porcine kidney model.
  
  
  METHODS
  A multiline monopolar dry electrode (impedance-based system), a multiline monopolar dry electrode (temperature-based system), a single monopolar wet electrode (impedance-based system) and a single monopolar dry, internally-cooled electrode (impedance-based system) were selected. RF energy was applied at different treatment parameters (power with and without control, tissue temperature, saline enhancement) for 1, 3, 5 and 9 minutes in healthy perfused ex vivo porcine tissue. Each treatment parameter was repeated 5 times. Maximum vertical, long-axis and short-axis diameters of the macroscopic lesion were measured and lesion volumes/ shapes were calculated.
  
  
  RESULTS
  Lesion volumes increased significantly with the pre-selected tissue temperature and saline enhancement. Saline enhancement created larger, but irregular shaped lesions. The impedance-based system created lesion volumes that were predictable by treatment time and generator power. Lesions were unpredictable when uncontrolled generator power was applied. The created lesion shape was dependent on the selected electrode configuration.
  
  
  CONCLUSIONS
  The currently available monopolar RFA systems offer different specific technical features to control tissue ablation. Detailed knowledge of the specific characteristics of each RF system is necessary to provide a higher chance of successful clinical outcome by complete and reliable ablation.
authors.affiliation: Department of Urology, University Hospital Mannheim, Faculty of Clinical Medicine Mannheim, Ruprecht-Karls University of Heidelberg, Germany. axel.haecker@chir.ma.uni-heidelberg.de
authors.forename: Axel
authors.initials: A
authors.lastname: Häcker
authors.forename: Stefan
authors.initials: S
authors.lastname: Vallo
authors.forename: Christel
authors.initials: C
authors.lastname: Weiss
authors.forename: Rainer
authors.initials: R
authors.lastname: Grobholz
authors.forename: Peter
authors.initials: P
authors.lastname: Alken
authors.forename: Thomas
authors.initials: T
authors.lastname: Knoll
authors.forename: Maurice Stephan
authors.initials: MS
authors.lastname: Michel
mesh_terms: D000818:Animals; D001831:Body Temperature; D002292:Carcinoma, Renal Cell / Q000473:pathology / Q000601:surgery*; D017115:Catheter Ablation / Q000295:instrumentation*; D004195:Disease Models, Animal; D017097:Electric Impedance; D004567:Electrodes, Implanted; D004867:Equipment Design; D007680:Kidney Neoplasms / Q000473:pathology / Q000601:surgery*; D019060:Minimally Invasive Surgical Procedures; D013552:Swine; D047368:Tumor Burden