Li Sinan, Lin Shengtao, Cheng Yi, Matsunaga Terry O, Eckersley Robert J, Tang Meng-Xing
Department of Bioengineering, Imperial College London, London, UK.
Department of Medical Imaging, University of Arizona, Tucson, Arizona, USA.
Ultrasound Med Biol. 2015 May;41(5):1422-31. doi: 10.1016/j.ultrasmedbio.2014.12.021. Epub 2015 Feb 2.
Phase-change contrast agents in the form of nanoscale droplets can be activated into microbubbles by ultrasound, extending the contrast beyond the vasculature. This article describes simultaneous optical and acoustical measurements for quantifying the ultrasound activation of phase-change contrast agents over a range of concentrations. In experiments, decafluorobutane-based nanodroplets of different dilutions were sonicated with a high-pressure activation pulse and two low-pressure interrogation pulses immediately before and after the activation pulse. The differences between the pre- and post-interrogation signals were calculated to quantify the acoustic power scattered by the microbubbles activated over a range of droplet concentrations. Optical observation occurred simultaneously with the acoustic measurement, and the pre- and post-microscopy images were processed to generate an independent quantitative indicator of the activated microbubble concentration. Both optical and acoustic measurements revealed linear relationships to the droplet concentration at a low concentration range <10(8)/mL when measured at body temperature. Further increases in droplet concentration resulted in saturation of the acoustic interrogation signal. Compared with body temperature, room temperature was found to produce much fewer and larger bubbles after ultrasound droplet activation.
纳米级液滴形式的相变造影剂可通过超声激活成微泡，从而将造影范围扩展到血管系统之外。本文描述了用于量化一系列浓度下相变造影剂超声激活的同步光学和声学测量。在实验中，用高压激活脉冲和紧接在激活脉冲前后的两个低压询问脉冲对不同稀释度的基于十氟丁烷的纳米液滴进行超声处理。计算询问前后信号之间的差异，以量化在一系列液滴浓度范围内激活的微泡散射的声功率。光学观察与声学测量同时进行，对显微镜检查前后的图像进行处理，以生成激活的微泡浓度的独立定量指标。当在体温下测量时，光学和声学测量在低浓度范围<10(8)/mL时均显示出与液滴浓度的线性关系。液滴浓度的进一步增加导致声学询问信号饱和。与体温相比，发现室温下超声液滴激活后产生的气泡要少得多且大得多。
