Silicon carbide as a heat-enhancing agent in microwave ablation: in vitro experiments

Silicon carbide (SiC) is an inert compound material with excellent microwave absorption and heat-conducting properties. The aim of our study was to investigate the heat-enhancing effects of SiC in microwave ablation in an in vitro setting.

Different concentrations of SiC powder were mixed with 2% gelatin, producing a 20-ml mixture that was then heated with a clinical microwave ablation system (5 min/45 W). Temperature was measured continuously fiberoptically. Additional heating properties were assessed for the most heatable concentrations at different energy settings (10, 20, and 30 W). As reference, 2% gelatin without SiC was heated. Statistical evaluation by analysis of variance with post hoc Student-Newman-Keuls testing was performed.

For the different SiC concentrations, maximum temperatures measured were 45.7 ± 1.2°C (0% SiC, control), 50.4 ± 3.6°C (2% SiC), 60.8 ± 1.8°C (10% SiC), 74.9 ± 2.6°C (20% SiC), and 83.4 ± 2.5°C (50% SiC). Differences between all data points were significant (P < 0.05). Maximum temperatures that used 20% SiC were 36.3 ± 2.76°C (10 W), 48.7 ± 4.18°C (20 W), and 50.6 ± 0.68°C (30 W). The use of 50% SiC maximum temperatures resulted in values of 46.2 ± 2.52°C (10 W), 70.1 ± 0.64°C (20 W), and 83.0 ± 4.69°C (30 W). With 20% SiC and 50% SiC mixtures, the 10 W maximum temperatures were significantly lower than at all other power levels, and maximum temperatures with 20 and 30 W were significantly lower when compared with 45 W (P < 0.05).

SiC is a nontoxic, highly effective substance for enhancing microwave-induced heating with a microwave ablation system in vitro. These data suggest its usefulness for enhancement of ablative effects in percutaneous tumor therapy. Further investigations need to be performed to evaluate the ex vivo and in vivo ablation effects and the possible methods for administration of SiC particles.