Acoustic pressure change inside blood vessel exposed to high-intensity focused ultrasound: a simulation study

For the implementation of sonothrombolysis, the acoustic pressure inside the blood vessel should be revealed according to the ultrasound burst and biological tissue conditions. The objective of this study is to measure the magnitude of the acoustic pressure inside blood vessel exposed to high-intensity focused ultrasound (HIFU), and to reveal its changing characteristics according to the ultrasound parameters (power and frequency) and tissue configurations. The tissue mimicking phantom with HIFU exposure was modeled to simulate the acoustic pressure. The results showed that for a biological tissue system composed of skin, fat, muscle, and blood, the peak pressure at the focus with blood zone increased as the insonation frequency increased (0.5-2 MHz). Pressure attenuation with respect to blood vessel depth (10-30 mm) intensified according to increment of HIFU power and frequency. Greater attenuation was observed when the frequency surpassed 1.1 MHz, varying with skin (1-5 mm) and fat tissue (2-7 mm) thicknesses. The results suggest that at frequencies below 1.1 MHz, identical HIFU power can be utilized for different individuals and lesions, thereby achieving similar outcomes in clinical treatment.