title: Bipolar versus multipolar radiofrequency (RF) ablation for the treatment of renal cell carcinoma: differences in technical and clinical parameters.
abstract: OBJECTIVE
  This study aimed to compare retrospectively bipolar RF ablation with multipolar RF ablation for the treatment of renal cell carcinoma.
  
  
  METHODS
  Between March 2009 and June 2012, 12 tumours (nine patients) treated with bipolar RF ablation (one applicator) and 14 tumours (11 patients) treated with multipolar RF ablation (two applicators) were compared systematically. Selection between bipolar RF ablation and multipolar RF ablation was operator choice considering tumour size. Study goals included differences in tumour and coagulation extent, and technical parameters (total RF energy delivery and RF ablation time per coagulation volume).
  
  
  RESULTS
  Tumour maximum diameter was significantly larger for multipolar RF ablation compared with bipolar RF ablation (27.0 mm versus 19.4 mm; p < 0.01). This difference is partially dependent on operator choice. Coagulation length, width and volume were significantly larger for multipolar RF ablation compared with bipolar RF ablation (35.0 mm versus 26.5 mm, 27.5 mm versus 23.0 mm and 14.3 cm(3) versus 8.1 cm(3); p < 0.01, p < 0.05 and p < 0.05, respectively). Coagulation circularity was not significantly different between both study groups (0.8 versus 0.8; not significant). Total RF energy delivery was significantly higher and RF ablation time per coagulation volume was significantly shorter for multipolar RF ablation compared with bipolar RF ablation (52.0 kJ versus 28.6 kJ and 2.4 min/cm(3) versus 4.1 min/cm(3); p < 0.05 and p < 0.05, respectively).
  
  
  CONCLUSIONS
  Multipolar RF ablation creates a significantly larger coagulation width, but identical coagulation shape, compared with bipolar RF ablation. Additionally, multipolar RF ablation coagulates faster according to the shorter RF ablation time per coagulation volume.
authors: Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Germany. christof.sommer@med.uni-heidelberg.de
authors: Christof M
authors: CM
authors: Sommer
authors: Guenther
authors: G
authors: Lemm
authors: Ernst
authors: E
authors: Hohenstein
authors: Ulrike
authors: U
authors: Stampfl
authors: Nadine
authors: N
authors: Bellemann
authors: Dogu
authors: D
authors: Teber
authors: Jens
authors: J
authors: Rassweiler
authors: Hans U
authors: HU
authors: Kauczor
authors: Boris A
authors: BA
authors: Radeleff
authors: Philippe L
authors: PL
authors: Pereira
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000473:pathology / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology / Q000601:surgery*; D008297:Male; D047368:Tumor Burden