Sijl Jeroen, Gaud Emmanuel, Frinking Peter J A, Arditi Marcel, de Jong Nico, Lohse Detlef, Versluis Michel
Physics of Fluids Group, University of Twente, Enschede, The Netherlands.
J Acoust Soc Am. 2008 Dec;124(6):4091-7. doi: 10.1121/1.2997437.
Individual ultrasound contrast agent microbubbles (BR14) were characterized acoustically. The bubbles were excited at a frequency of 2 MHz and at peak-negative pressure amplitudes of 60 and 100 kPa. By measuring the transmit and receive transfer functions of both the transmit and receive transducers, echoes of individual bubbles were recorded quantitatively and compared to simulated data. At 100 kPa driving pressure, a second harmonic response was observed for bubbles with a size close to their resonance size. Power spectra were derived from the echo waveforms of bubbles of different sizes. These spectra were in good agreement with those calculated from a Rayleigh-Plesset-type model, incorporating the viscoelastic properties of the phospholipid shell. Small bubbles excited below their resonance frequency have a response dominated by the characteristics of their phospholipid shell, whereas larger bubbles, excited above resonance, have a response identical to those of uncoated bubbles of similar size.
对单个超声造影剂微泡（BR14）进行了声学表征。这些微泡在2 MHz的频率以及60和100 kPa的负峰值压力振幅下被激发。通过测量发射和接收换能器的发射和接收传递函数，对单个微泡的回波进行了定量记录，并与模拟数据进行了比较。在100 kPa的驱动压力下，观察到尺寸接近其共振尺寸的微泡出现二次谐波响应。从不同尺寸微泡的回波波形中导出了功率谱。这些谱与根据包含磷脂壳粘弹性特性的瑞利-普莱斯模型计算出的谱高度一致。在低于其共振频率下激发的小微泡，其响应主要由磷脂壳的特性决定，而在高于共振频率下激发的较大微泡，其响应与类似尺寸的未包被微泡相同。
