title: Laparoscopic and computed tomography-guided percutaneous radiofrequency ablation of renal tissue: acute and chronic effects in an animal model.
abstract: OBJECTIVE
  To evaluate the laparoscopic and percutaneous delivery of impedance-based radiofrequency ablation (RFA) of the kidney by studying the acute and chronic clinical, radiographic, and histopathologic effects in the porcine model.
  
  
  METHODS
  Eight kidneys from 4 pigs underwent laparoscopic RFA. Six kidneys from 3 additional pigs received computed tomography (CT)-guided, percutaneous RFA. CT scans were performed immediately after RFA and before harvest at 2 hours, 24 hours, 3 weeks, and 13 weeks. The gross, radiographic, and histopathologic changes were recorded for each period.
  
  
  RESULTS
  Grossly, the RFA lesions were sharply demarcated, measuring 3 to 5 cm. Two major complications (14%) occurred (one urinoma, one psoas muscle injury) in 14 ablations. No deaths or significant blood loss occurred as a result of RFA. Radiographically, the immediate CT scanning demonstrated small perinephric hematomas and wedge-shaped defects. Delayed CT showed nonenhancing defects up to 5 cm. Color-flow and power Doppler were unable to distinguish significant tissue changes during RFA. The histopathologic evaluation revealed marked inflammation surrounding the necrotic regions in the early lesions; chronic lesions were characterized by dense fibrosis. The tissue temperatures ranged from 62 degrees to 118 degrees C in the area of ablation.
  
  
  CONCLUSIONS
  RFA is readily delivered laparoscopically or percutaneously with minimal morbidity. Impedance-based application of radiofrequency energy allows monitoring and control of ablation. Using a multi-antenna probe, areas of tissue up to 5 cm can be completely destroyed. The RFA lesion can be monitored as a nonenhancing cortical defect on CT.
authors.affiliation: Wilford Hall Medical Center, San Antonio, Texas, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Crowley
authors.forename: J
authors.initials: J
authors.lastname: Shelton
authors.forename: A J
authors.initials: AJ
authors.lastname: Iverson
authors.forename: M P
authors.initials: MP
authors.lastname: Burton
authors.forename: N C
authors.initials: NC
authors.lastname: Dalrymple
authors.forename: J T
authors.initials: JT
authors.lastname: Bishoff
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000009:adverse effects / Q000379:methods*; D005240:Feasibility Studies; D006406:Hematoma / Q000209:etiology; D007668:Kidney / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D007673:Kidney Cortex Necrosis / Q000209:etiology / Q000473:pathology; D007674:Kidney Diseases / Q000209:etiology; D010535:Laparoscopy / Q000379:methods*; D016343:Monitoring, Intraoperative / Q000379:methods; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*