Synergy between high intensity focused ultrasound and ethanol injection in ablation of thyroid cancer cells

Abstract

We have investigated the combination of high intensity focused ultrasound (HIFU) and ethanol injection for ablation treatment of anaplastic thyroid cancer, a highly aggressive form of thyroid cancer characterized by >80% mortality within months. The suspension of FB1 anaplastic thyroid cancer cells (100 μl, 2.7 million cells/ml) were placed in a 0.2 ml thin-wall PCR tube and then exposed to HIFU alone, ethanol alone, or ethanol + HIFU. The focused ultrasound signal was generated by a 1.1 MHz transducer with acoustic power ranged from 4.1 W to 12.0 W. Ethanol was diluted in the FB1 cell growth medium to the concentration of 2%, 4%, or 10% (v/v) and applied to the cells before HIFU exposure. The viability of the cells was measured by flow cytometry and trypan blue exclusion 2, 24, and 72 h post-treatment. The exposure of FB1 cells to HIFU alone greatly reduced the number of viable cells immediately after treatment; however, their proliferation rate remained high. On the other hand, both the viability and proliferation rate significantly decreased in the cells treated with both ethanol and HIFU. In conclusion, percutaneous ethanol injection (PEI) and HIFU have a synergistic effect on anaplastic thyroid cancer ablation.