Department of Biomedical Imaging and Radiological Sciences, School of Biomedical Science and Engineering, National Yang-Ming University, Taipei, Taiwan.
IEEE Trans Ultrason Ferroelectr Freq Control. 2009 Dec;56(12):2643-9. doi: 10.1109/TUFFC.2009.1355.
Continuous high-intensity focused ultrasound (HIFU) at various intensities has been shown to induce functional changes in arteries. The objective of the current study was to investigate the functional changes in arteries when pulsed HIFU is used at various acoustic power levels. Sonication was applied at an ultrasound frequency of 1 MHz with a burst length of 50 ms and a repetition frequency of 1 Hz. The duration of the whole sonication was 6 s. The femoral arteries and abdominal aortas of Sprague-Dawley rats were surgically exposed and sonicated with pulsed HIFU; the pulsed-HIFU beam was aimed using color images of the blood flow. The peak systolic velocity (PSV) of the blood flow, as measured by Doppler velocimetry, increased in the arteries to which pulsed HIFU had been applied at acoustic powers of 15, 30, and 45 W. The increase in PSV was correlated with the acoustic power of the pulsed HIFU. The temperatures recorded by the thermocouples placed above and below the aorta surfaces did not change significantly during the sonication. Furthermore, no histological changes were found and the vessel wall showed no obvious temperature rise. Therefore, our results indicate that the functional changes induced by pulsed-HIFU exposure are mainly due to mechanical effects.
连续高强度聚焦超声（HIFU）在不同强度下已被证明会引起动脉的功能变化。本研究的目的是研究脉冲 HIFU 在不同声功率水平下使用时动脉的功能变化。超声在 1 MHz 的超声频率下应用，脉冲长度为 50 ms，重复频率为 1 Hz。整个超声持续时间为 6 s。通过彩色血流图像引导，手术暴露 Sprague-Dawley 大鼠的股动脉和腹主动脉，并对其进行脉冲 HIFU 超声处理；应用多普勒速度仪测量血流的收缩期峰值速度（PSV），发现施加脉冲 HIFU 的动脉的 PSV 在声功率为 15、30 和 45 W 时增加。PSV 的增加与脉冲 HIFU 的声功率相关。在超声处理过程中，放置在主动脉表面上方和下方的热电偶记录的温度没有明显变化。此外，没有发现组织学变化，血管壁也没有明显升温。因此，我们的结果表明，脉冲 HIFU 照射引起的功能变化主要归因于机械效应。
