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 imped ance-based radiofrequency ablation (RFA) of the kidney by studying the acut e and chronic clinical, radiographic, and histopathologic effects in the po rcine model. Methods. Eight kidneys from 4 pigs underwent laparoscopic RFA. Six kidneys from 3 additional pigs received computed tomography (CT)-guided, percutaneo us 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 his topathologic 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 sma ll perinephric hematomas and wedge-shaped defects. Delayed CT showed nonenh ancing defects up to 5 cm. Color-flow and power Doppler were unable to dist inguish significant tissue changes during RFA. The histopathologic evaluati on revealed marked inflammation surrounding the necrotic regions in the ear ly lesions; chronic lesions were characterized by dense fibrosis. The tissu e temperatures ranged from 62 degrees to 118 degreesC in the area of ablati on. Conclusions, RFA is readily delivered laparoscopically or percutaneously wi th minimal morbidity. Impedance-based application of radiofrequency energy allows monitoring and control of ablation. Using a multiantenna probe, area s of tissue up to 5 cm can be completely destroyed. The RFA lesion can be m onitored as a nonenhancing cortical defect on CT. UROLOGY 57: 976-980, 2001 . (C) 2001, Elsevier Science Inc.