Ultrastructural observation of liver tissue ablation induced by high-intensity focused ultrasound.

ABSTRACT

AIM: To observe the ultrastructural changes of liver tissues on normal rabbit ablated by high-intensity focused ultrasound (HIFU). METHODS: A single shot of 1.1 MHz focused ultrasound at an intensity of 500 W/cm(2) with 20-s duration of continuous exposure was applied intraoperatively in normal rabbit livers. Ultrastructural changes of the sonoablated lesion, as viewed by light and electron microscopy, were observed. RESULTS: Liver cells at the center of the sonoablated lesion showed irreversible degeneration immediately after HIFU treatment; electron microscopy showed that although the liver cells appeared normal histologically, irregularly shaped cavities of about 0.3-0.5 µm in diameter were present in the cytoplasm. CONCLUSION: Thermal damages may be the main mechanism of HIFU-induced ablation of liver tissues besides cavitation effect.