Determination of postexcitation thresholds for single ultrasound contrast agent microbubbles using double passive cavitation detection
Determination of postexcitation thresholds for single ultrasound contrast agent microbubbles using double passive cavitation detection
复制标题
DOI：
10.1121/1.3373405
复制
发表时间：
2010-06-01
影响因子：
2.4
通讯作者：
O'Brien, William D., Jr.
中科院分区：
文献类型：
--
作者：
King, Daniel A.;Malloy, Michael J.;O'Brien, William D., Jr.
这项工作提出了单一的超声造影剂的实验响应短，大幅度脉冲，其特征在于使用双被动空化检测。在该技术中，两个匹配的聚焦接收换能器正交对齐，以捕获来自重叠共焦区域内的微泡的声学响应。根据基于存在或不存在激发后信号的分类方案对微泡进行分类，所述激发后信号是遵循超声造影剂的主要振荡响应的次级宽带尖峰，并且指示微泡的瞬时塌陷。对两种类型的造影剂（和）进行不同的声穿透频率（0.9、2.8、4.6和7.1 MHz）和峰值稀疏压力（200 kPa至6.2 MPa）的实验。使用逻辑回归分析拟合结果，以定义压力阈值，其中每个频率至少5%和50%的微泡群体塌陷。在所研究的频率范围内，发现Determination的这些阈值发生在比Optison更低的压力下;此外，在大多数情况下，两种微泡类型的阈值发生在更低的压力和更低的频率下，尽管这种趋势不遵循机械指数缩放。(C)2010年美国声学学会。[DOI：10.1121/1.3373405]
This work presents experimental responses of single ultrasound contrast agents to short, large amplitude pulses, characterized using double passive cavitation detection. In this technique, two matched, focused receive transducers were aligned orthogonally to capture the acoustic response of a microbubble from within the overlapping confocal region. The microbubbles were categorized according to a classification scheme based on the presence or absence of postexcitation signals, which are secondary broadband spikes following the principle oscillatory response of the ultrasound contrast agent and are indicative of the transient collapse of the microbubble. Experiments were conducted varying insonifying frequencies (0.9, 2.8, 4.6, and 7.1 MHz) and peak rarefactional pressures (200 kPa to 6.2 MPa) for two types of contrast agents (Definity (R) and Optison (TM)). Results were fit using logistic regression analysis to define pressure thresholds where at least 5% and 50% of the microbubble populations collapsed for each frequency. These thresholds were found to occur at lower pressures for Definity than for Optison over the range of frequencies studied; additionally, the thresholds occurred at lower pressures with lower frequencies for both microbubble types in most cases, though this trend did not follow a mechanical index scaling. (C) 2010 Acoustical Society of America. [DOI: 10.1121/1.3373405]