Hydrodissection in microwave ablation: the effectiveness of 0.9 % NaCl versus 5 % dextrose in an ex vivo experimental set-up

To compare the effectiveness of hydrodissection using 0.9 % NaCl (saline) or 5 % dextrose in water during microwave ablation at different hydrodissection fluid thicknesses, in an ex vivo experimental set-up. Two porcine liver parts were placed in a plastic container simulating a superficial liver ablation with adjacent tissue. The space between the livers was filled with either saline or 5 % dextrose in water. Microwave ablation was performed 4 min at 100 W, at 15 mm from the liver surface. Three thermocouples were used to determine the heat propagation: (1) between the microwave ablation antenna and liver surface; (2) 5 mm from the surface of the adjacent tissue; (3) 15 mm from the surface of the adjacent tissue. Forty experiments were performed using hydrodissection fluid thicknesses ranging from 1 to 10 mm. The maximum temperature increase for each thermocouple was determined. A Spearman's correlation analysis assessed the relationship between the hydrodissection fluid thickness (in millimeters) and the temperature increase (in degrees Celsius) per fluid. At 5 mm within the adjacent tissue, use of 1 mm hydrodissection fluid thickness with 5 % dextrose in water resulted in less temperature increase (4.6 °C) compared to saline (6.8 °C). Additionally, at this distance, a negative correlation was observed between hydrodissection fluid thickness and temperature increase for both saline hydrodissection (r(18) = -0.96, p < 0.001) and 5 % dextrose in water hydrodissection (r(18) = -0.81, p < 0.001), which differs significantly (p = 0.011). Results from this experimental ex vivo study suggest that 5 % dextrose in water may protect adjacent critical structures better from heating during microwave ablation than saline.