Expansion of radiofrequency ablation volume by saturated NaCL saline injection in the area of vaporization

Abstract

Vaporization around the radiofrequency (RF) electrode after RF application (RFA) limits the RF ablation area. To determine whether saturated saline injected into the area of vaporization after initial RFA extends ablation area after further RFA. RFA was performed in 18 ex vivo porcine livers and four in vivo rabbit erector spinae muscles. An RF electrode was used to ablate an area with 40W of parallel current for 15 min. The ablation margin was determined using a thermocouple, and the radius of the ablated area was measured. After RF electrode removal, saturated saline was infused through a percutaneous ethanol injection needle into the site of the original RFA in 11 liver samples and two erector spinae muscles. Three minutes later, RFA was resumed for 15 min. The remaining seven control liver samples and two spinae muscles received RFA without saline injection. The radius of the final ablated area was then measured. In the ex vivo study, injection of saturated saline significantly decreased tissue impedance (87.7+/-9.4 to 51.1+/-9.7 Omega, P<0.0001), and increased the mean radius of the ablated area (15.9+/-3.0 to 25.0+/-3.6 mm, P<0.0001). These significant changes were not observed without injection of saturated saline. Similar trends were found in the in vivo study. Injection of saturated saline into the area of vaporization around the RF electrode, followed by additional RFA, caused concentric expansion of the final ablation area, facilitating more efficient tumor ablation.