title: Clinical efficacy of bipolar radiofrequency ablation of small renal masses.
abstract: OBJECTIVE
  The new development of bipolar radiofrequency ablation (RFA) can overcome problems observed with monopolar RFA for the treatment of small renal masses (SRM). Energy is more homogeneously delivered, and higher current densities can be used. Data on treatment of renal tumors with bipolar RFA are still limited. The aim of this study was to examine the clinical efficacy of bipolar multiprobe RFA for treatment of SRM, according to the IDEAL recommendations.
  
  
  METHODS
  Ten SRMs in 10 consecutive patients were ablated using multipolar RFA. Outcome measures were technical success, applied energy, and observed complications. Hereafter, tumors were excised in an open surgical fashion and histologically analyzed for RFA lesion volume and presence of viable cells.
  
  
  RESULTS
  Median patient age was 59.5 (range 39.2-69.8) years. Median tumor diameter was 2.5 (range 1.6-4.5) cm. Technical success rate was 100 %. In five procedures, two probes were used, and in five procedures three probes were used. Median ablation time was 18 (range 12-38) minutes in which a median of 30.5 (range 23.6-102) kJ was applied. Complications included one patient who developed a urinoma. Median ablated volume was 4.4 (2.2-29.9) cm(3). In all cases, the ablated volume was larger than the tumor. No viable cells were present within the ablated tissue.
  
  
  CONCLUSIONS
  Multipolar RFA is clinically successful for treating SRMs. Using preoperatively calculated energy settings, tailored size tumor lesions could be created. Clinical efficacy and oncological outcomes need to be investigated further in studies using multipolar RFA in a percutaneous fashion.
authors.affiliation: Department of Urology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands. s.kroeze@jbz.nl.
authors.forename: S G C
authors.initials: SG
authors.lastname: Kroeze
authors.affiliation: Department of Urology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Agenant
authors.affiliation: Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: G N
authors.initials: GN
authors.lastname: Jonges
authors.affiliation: Olympus Surgical Technologies Europe, Teltow, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Stein
authors.affiliation: Department of Urology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
authors.forename: J L H R
authors.initials: JL
authors.lastname: Bosch
mesh_terms: D000328:Adult; D000368:Aged; D017115:Catheter Ablation / Q000379:methods*; D006801:Humans; D007680:Kidney Neoplasms / Q000175:diagnosis / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D061646:Operative Time; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden
keywords: Bipolar; Kidney cancer; Multiprobe; Radiofrequency ablation; Small renal masses