低环境压力下超声造影剂微泡高频次谐波散射特性的实验研究

Experimental study on high-frequency subharmonic scattering characteristics of ultrasound contrast agent microbubbles under low ambient pressure

超声造影剂微泡非线性次谐波散射与环境压力之间的相关性有望用于局部脑组织压力的监测。尽管高频超声实现了颅内微血管的高分辨成像,但是当前对微泡的高频次谐波散射特性研究不充分,制约了基于微泡高频次谐波散射估测局部脑组织压力的研究进展。因此,本研究以离体方式探索了在10 MHz高频超声激励下,不同声压和环境压力对声诺维(SonoVue)、示卓安(Sonazoid)和华声显三种超声造影剂微泡高频次谐波散射特性的影响。结果显示,在696、766、817 kPa的峰负声压下,三种微泡的次谐波散射幅度均随着环境压力的增加而增长,且次谐波幅值与压力之间具有良好的线性相关性。在上述三个声压下,声诺维的相关性系数最高可达0.948(P=0.03),测压灵敏度最高为0.248 dB/mm Hg,均方根误差(RMSE)最小为2.64 mm Hg;示卓安的相关性系数最高可达0.982(P<0.01),测压灵敏度最高为0.052 dB/mm Hg,RMSE最小为1.51 mm Hg;华声显的相关性系数最高可达0.969(P=0.02),测压灵敏度最高为0.098 dB/mm Hg,RMSE最小为2.00 mm Hg。以上离体实验结果表明,通过选择超声造影剂微泡并优化声压,可以改进微泡的高频次谐波散射与环境压力之间的相关关系、提高测压灵敏度、减小测量误差,以满足临床对局部脑组织压力测量的需求,这为后续在体研究提供了重要的实验依据。

Correlation between nonlinear subharmonic scattering of ultrasound contrast agent microbubbles and ambient pressure is expected to be used for local brain tissue pressure monitoring.Although high-frequency ultrasound has achieved high-resolution imaging of intracranial microvessels,the research on high-frequency subharmonic scattering characteristics of microbubbles is insufficient at present,which restricts the research progress of estimating local brain tissue pressure based on high-frequency subharmonic scattering of microbubbles.Therefore,under the excitation of 10 MHz high-frequency ultrasound,the effects of different acoustic pressures and ambient pressures on the high-frequency subharmonic scattering characteristics of three different ultrasound contrast agents including SonoVue,Sonazoid and Huashengxian were investigated in this in vitro study.Results showed that the subharmonic scattering amplitudes of the three microbubbles increased with the increase of ambient pressure at the peak negative acoustic pressures of 696,766 and 817 kPa,and there was a favorable linear correlation between subharmonic amplitude and ambient pressure.Under the above three acoustic pressures,the highest correlation coefficient of SonoVue was 0.948(P=0.03),the highest sensitivity of pressure measurement was 0.248 dB/mm Hg and the minimum root mean square error(RMSE)was 2.64 mm Hg.Sonazoid's highest correlation coefficient was 0.982(P<0.01),the highest sensitivity of pressure measurement was 0.052 dB/mm Hg and the minimum RMSE was 1.51 mm Hg.The highest correlation coefficient of Huashengxian was 0.969(P=0.02),the highest sensitivity of pressure measurement was 0.098 dB/mm Hg and the minimum RMSE was 2.00 mm Hg.The above in vitro experimental results indicate that by selecting ultrasound contrast agent microbubbles and optimizing acoustic pressure,the correlation between high-frequency subharmonic scattering of microbubbles and ambient pressure can be improved,the sensitivity of pressure measurement can be upgraded,and the measurement error can be reduced to meet the clinical demand for local brain tissue pressure measurement,which provided an important experimental basis for subsequent research in vivo.