Ex vivo experiment on radiofrequency liver ablation with saline infusion through a screw-tip cannulated electrode

Purpose: To investigate whether radiofrequency (RF) therapy with hypertonic saline infusion through a hollow screw-tip electrode can cause a lesion size suitable for liver tumor ablation. Materials and methods: RF tissue ablation of 180 sites was performed by using a hollow screw-tip electrode in 40 freshly excised swine livers. Under both power and temperature control modes, the ablation effects with and without various regimes of 5% hypertonic saline (1 ml/min) prior to and/or during the procedure were compared by measuring the size of lesions at dissection and confirmed by T1 and T2 weighted magnetic resonance (MR) imaging. Results: The maximal lesion diameter of 5.5 cm was reached at 30 W with saline infusion 1 min prior to and during 12 min of ablation. The smaller sizes (P < 0.01) between 0.3 and 2.5 cm in diameter were met with noninfusion or preinfusion-only groups. The RF ablation lesions appeared as hyper-and hypointense areas on T1 and T2 MR images, respectively. Conclusions: RF ablation in combination with present hollow screw-tip electrode and saline infusion allows for necrotic development of suitable size for liver tumor ablation. Such ablated lesions can be visualized with MR imaging. (C) 1997 Academic Press.