Modifying the size distribution of microbubble contrast agents for high-frequency subharmonic imaging
Modifying the size distribution of microbubble contrast agents for high-frequency subharmonic imaging
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DOI：
10.1118/1.4813017
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发表时间：
2013-08-01
期刊：
影响因子：
3.8
通讯作者：
Doyley, Marvin M.
中科院分区：
文献类型：
--
作者：
Shekhar, Himanshu;Rychak, Joshua J.;Doyley, Marvin M.
用途：次谐波成像对于高频（>10 MHz）非线性成像是感兴趣的，因为它可以特异性地检测超声造影剂（UCA）的响应。然而，传统的UCA在高频下产生弱的次谐波响应，这限制了次谐波成像的灵敏度。我们假设，修改剂的尺寸分布可以增强其高频次谐波响应。本研究的总体目标是调查药物的大小操纵群体，以确定在高频（在这种情况下，20 MHz）下产生最强次谐波响应的大小范围。第二个目标是评估是否数量或体积加权的大小分布更好地代表了高频率次谐波imaging.Methods的代理的功效：作者创建了六个不同的代理大小分布从本地分布的市售UCA（Targestar-P（R））。本地代理的中位数（数量加权）直径为1.63 μ m，而大小操纵的人口的中位数直径范围从1.35到2.99 μ m。作者进行了声学测量与本地和大小操纵代理人口，以评估他们的次谐波响应20 MHz的激励（脉冲持续时间1.5 μ s，压力振幅100-398 kPa）。结果：结果显示了相当大的差异的次谐波响应的代理人口进行了调查。次谐波响应峰值为代理人口的中位数直径为2.15 μ m，这表明了一个次谐波信号，是8分贝高于本地代理。比较不同的UCA人口的次谐波响应表明，直径在1.3和3 μ m之间的微泡是在20 MHz的次谐波响应的主要贡献者。此外，一个更好的相关性之间的次谐波响应的代理和数量加权的大小分布（R-2 = 0.98）比与体积加权的大小分布（R-2 = 0.53）。结论：修改的大小分布的代理似乎是一个可行的策略，以提高灵敏度的高频次谐波成像。此外，当UCA的尺寸分布未被适当修改时，数量加权尺寸分布是准确描述用于高频次谐波成像的药剂的功效的有用参数。(C)2013年美国医学物理学家协会。
Purpose: Subharmonic imaging is of interest for high frequency (>10 MHz) nonlinear imaging, because it can specifically detect the response of ultrasound contrast agents (UCA). However, conventional UCA produce a weak subharmonic response at high frequencies, which limits the sensitivity of subharmonic imaging. We hypothesized that modifying the size distribution of the agent can enhance its high-frequency subharmonic response. The overall goal of this study was to investigate size-manipulated populations of the agent to determine the range of sizes that produce the strongest subharmonic response at high frequencies (in this case, 20 MHz). A secondary goal was to assess whether the number or the volume-weighted size distribution better represents the efficacy of the agent for high-frequency subharmonic imaging.Methods: The authors created six distinct agent size distributions from the native distribution of a commercially available UCA (Targestar-P (R)). The median (number-weighted) diameter of the native agent was 1.63 mu m, while the median diameters of the size-manipulated populations ranged from 1.35 to 2.99 mu m. The authors conducted acoustic measurements with native and size-manipulated agent populations to assess their subharmonic response to 20 MHz excitation (pulse duration 1.5 mu s, pressure amplitudes 100-398 kPa).Results: The results showed a considerable difference between the subharmonic response of the agent populations that were investigated. The subharmonic response peaked for the agent population with a median diameter of 2.15 mu m, which demonstrated a subharmonic signal that was 8 dB higher than the native agent. Comparing the subharmonic response of different UCA populations indicated that microbubbles with diameters between 1.3 and 3 mu m are the dominant contributors to the subharmonic response at 20 MHz. Additionally, a better correlation was observed between the subharmonic response of the agent and the number-weighted size-distribution (R-2 = 0.98) than with the volume-weighted size distribution (R-2 = 0.53).Conclusions: Modifying the size distribution of the agent appears to be a viable strategy to improve the sensitivity of high-frequency subharmonic imaging. In addition, when the size distribution of the UCA has not been suitably modified, the number-weighted size distribution is a useful parameter to accurately describe the efficacy of the agent for high-frequency subharmonic imaging. (C) 2013 American Association of Physicists in Medicine.