Adjuvant Thermal Accelerant Gel Use Increases Microwave Ablation Zone Temperature in Porcine Liver as Measured by MR Thermometry

Purpose: To determine the effects of a thermal accelerant gel on temperature parameters during microwave liver ablation.

Materials and methods: Sixteen consecutive liver ablations were performed in 5 domestic swine under general anesthesia with (n = 8) and without (n = 8) administration of thermal accelerant gel. Ablation zone temperature was assessed by real-time MR thermometry, measured as maximum temperature (T_max) and the volume of tissue ≥ 60°C (V₆₀). Tissue heating rate, ablation zone shape, and thermal energy deposition using the temperature degree-minutes at 43°C (TDM43) index were also measured. Differences between groups were analyzed using generalized mixed modeling with significance set at P = .05.

Results: Mean peak ablation zone temperature was significantly greater with thermal accelerant use (mean T_max, thermal accelerant: 120.0°C, 95% confidence interval [CI] 113.0°C-126.9°C; mean T_max, control: 80.3°C, 95% CI 72.7°C-88.0°C; P < .001), and a significantly larger volume of liver tissue achieved or exceeded 60°C when thermal accelerant was administered (mean V₆₀, thermal accelerant: 22.2 cm³; mean V₆₀, control: 15.9 cm³; P < .001). Significantly greater thermal energy deposition was observed during ablations performed with accelerant (mean TDM43, thermal accelerant: 198.4 min, 95% CI 170.7-230.6 min; mean TDM43, control: 82.8 min, 95% CI 80.5-85.1 min; P < .0001). The rate of tissue heating was significantly greater with thermal accelerant use (thermal accelerant: 5.8 min ± 0.4; control: 10.0 min; P < .001), and accelerant gel ablations demonstrated a more spherical temperature distribution (P = .002).

Conclusions: Thermal accelerant use is associated with higher microwave ablation zone temperatures, greater thermal energy deposition, and faster and more spherical tissue heating compared with control ablations.