Laparoscopic and computed tomography-guided percutaneous radiofrequency ablation of renal tissue: Acute and chronic effects in an animal model

Objectives. 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 degreesC 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 multiantenna 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. UROLOGY 57: 976-980, 2001. (C) 2001, Elsevier Science Inc.