Saline-enhanced radio-frequency tissue ablation in the treatment of liver metastases

PURPOSE: To assess the effect of intraparenchymal saline injection on the results of radio-frequency (RF) tissue ablation. MATERIALS AND METHODS: Ex vivo and in vivo animal RF ablation was performed with and without intraparenchymal saline injection. Initially, saline was injected as a bolus (1-20 mL) before RF application. For subsequent in vivo studies, saline was injected as a bolus before RF application or continuously (1 mL/min) during RF application. Finally, 14 patients with liver metastases and one patient with primary cholangiocarcinoma were treated with the continuous infusion technique. A single RF electrode (tip exposure, 1-3 cm) was used with various ablation parameters. RESULTS: With pretreatment bolus injection of saline, lesions measured 1.4 cm ± 0.1, 1.6 cm ± 0.2, and 1.2 cm ± 0.1 in ex vivo liver, in vivo animal muscle, and in vivo animal liver, respectively. Without saline enhancement, lesion sizes were 1.0 ± 0.2, 1.2 ± 0.2, and 0.8 ± 0.1 cm, respectively. With continuous saline injection in in vivo pig liver, lesion size was 1.84.1 cm in diameter. In human tumors, necrosis volume was variable, but complete necrosis was seen in 13 of 25 lesions (diameter, 1.2- 3.9 cm). Partial necrosis greater than 50% was seen in 12 lesions (diameter, 1.5- 4.5 cm). CONCLUSION: Saline-enhanced RF ablation might permit percutaneous destruction of large liver lesions.