title: Percutaneous radiofrequency ablation of liver tumors with the LeVeen probe: is roll-off predictive of response?
abstract: OBJECTIVE
  The LeVeen radiofrequency (RF) probe uses roll-off of electrical impedance as the endpoint for RF cautery of hepatic tumors. The purpose of this study is to determine the relation of roll-off to local control of hepatic tumors.
  
  
  METHODS
  Twenty hepatic tumors, including 10 hepatomas and 10 metastases, were treated. Lesions ranged from 1.4 cm to 6.0 cm in diameter; 13 (57%) were smaller than 3.0 cm. Each lesion was ablated with use of the LeVeen 15-gauge RF needle according to the manufacturer's protocol. Five patients underwent chemoembolization the day before. Patients were followed up with contrast-enhanced computed tomography or magnetic resonance imaging at 1 month and every 3 months thereafter.
  
  
  RESULTS
  Among the 20 lesions, roll-off was achieved at all burn locations in 11 (55%), no burn locations in eight (40%), and two of three burn locations in one (5%). Roll-off was observed in all patients who had undergone chemoembolization the day before. Six local recurrences occurred, five after RF ablation without roll-off and one after RF ablation with roll-off. According to life-table analysis, the local recurrence rate at 6 months without roll-off was 43% and with roll-off was 15% (P =.024; OR = 8.3; 95% CI = 0.93-66).
  
  
  CONCLUSIONS
  Roll-off is a significant predictor of local control after RF ablation. Strategies to enhance roll-off, such as concurrent embolization, may be important to optimize the therapeutic effect of this device.
authors: Division of Interventional Radiology, Department of Radiology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA.
authors: M A
authors: MA
authors: Arata
authors: H L
authors: HL
authors: Nisenbaum
authors: T W
authors: TW
authors: Clark
authors: M C
authors: MC
authors: Soulen
mesh_terms: D017115:Catheter Ablation / Q000379:methods*; D017097:Electric Impedance; D005260:Female; D006801:Humans; D015993:Life Tables; D008113:Liver Neoplasms / Q000175:diagnosis / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis; D011846:Radio Waves; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome