Subharmonic backscattering from ultrasound contrast agents
Subharmonic backscattering from ultrasound contrast agents
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DOI：
10.1121/1.428142
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发表时间：
1999-10-01
影响因子：
2.4
通讯作者：
Newhouse, VL
中科院分区：
文献类型：
--
作者：
Shankar, PM;Krishna, PD;Newhouse, VL
通过向血液中注入气泡或空心微球，可以提高组织中血液的超声对比度，这是超声估计组织灌注所需的。研究表明，利用辐照微球产生的次谐波可以获得更大的对比度改善。通过得到包覆微泡修正RPNNP方程的解析解，建立了包覆微泡物理参数与阈值压力之间的关系。通过引入被封装气泡的“声半径”概念来解释被封装微球共振频率的增加。据预测，造影剂的次谐波产生需要一个阈值的共振压力，当微球以其共振频率的两倍共振时，应该是最小的。实验证实了该最佳入射频率和产生次谐波的相当低的阈值压力的存在。造影剂中亚谐波产生的低阈值压力的存在可能在超声造影剂成像中证明是非常有价值的。(C) 1999美国声学学会。[s0001 - 4966(99) 01510 - 6]。
The ultrasonic contrast of blood in tissue, which is needed for ultrasonic estimation of tissue perfusion, can be increased by injecting the blood with bubbles or hollow microspheres. It has been shown that an even greater improvement in contrast can be obtained by using the subharmonic generated by irradiated microspheres. By obtaining analytical solutions to the modified RPNNP equation for a coated microbubble, the relationship between the physical parameters of the encapsulated bubble and the threshold pressure is established. The observed increase in the resonance frequency of a coated microsphere is explained by introducing the concept of "acoustic radius" of the encapsulated bubble. It is predicted that subharmonic generation in contrast agents requires a threshold insonifying pressure, and should be a minimum when microspheres are insonated at twice their resonance frequency. Experiments confirm the existence of this optimum incident frequency and of a reasonably low threshold pressure for the generation of the subharmonic. The existence of the low threshold pressures for subharmonic generation in contrast agents may prove to be very valuable in ultrasonic contrast imaging. (C) 1999 Acoustical Society of America. [S0001-4966(99)01510-6].