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Interstitial changes and their resolution after ultrasound guided radiofrequency induced ablation in porcine liver Buczkowski, Andrzej K.


Background: Radiofrequency ablation (RFA) is a new minimally invasive technique for the treatment of primary and secondary liver tumours. No complications have been reported to date in cases of experimental application involving animal (guinea pig, rat, porcine) models, however previous studies have not specifically addressed its safety in relation to changes induced in the normal hepatic parenchyma surrounding the lesion treated by RFA. Methods: Radiofrequency ablation was performed in both the right and left liver lobes of 28 female domestic swine. The animals were divided into four groups based on the attempted thermal injury to: hepatic veins; portal veins and bile ducts; diaphragm; and injury resulting from excessive radiofrequency (RF) energy delivery. RF lesions were followed with ultrasound examination, and gross and histologic examination was performed on the left lobe lesions on day 3 and the right lobe lesions on day 30. Results: There was no evidence of injury to main hepatic or portal vessels or bile ducts. Superficial and deep diaphragmatic burns were observed on day 3, but these were all completely healed by day 30. Full-thickness burns of the stomach and jejunum (one case of each) were encountered in separate experiments. There were no treatment-related deaths. No bile leak, bilomas, bleeding or abscesses were observed. The histologic pattern of RFA induced necrosis and tissue healing was consistent through all the cases and was related to the amount of energy delivered to the experiment area. Ultrasound proved to be an efficient method in RF probe placement and initial treatment, however its follow-up accuracy declines with the time after the RFA. Conclusions: Hepatic RFA is a safe procedure. No serious complications were observed with intrahepatic ablations. Thermal injuries were however produced in contiguous extrahepatic structures, when RFA was applied to superficial, subcapsular liver. These observations suggest the need for extreme attention during the treatment sessions and evaluation of laparoscopy as the preferred mode of the RF ablation delivery.

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