High-frequency subharmonic pulsed-wave Doppler and color flow imaging of microbubble contrast agents
High-frequency subharmonic pulsed-wave Doppler and color flow imaging of microbubble contrast agents
复制标题
DOI：
10.1016/j.ultrasmedbio.2007.12.011
复制
发表时间：
2008-07-01
影响因子：
2.9
通讯作者：
Foster, F. S.
中科院分区：
文献类型：
--
作者：
Needles, A.;Goertz, D. E.;Foster, F. S.
最近的一项研究表明，在20 MHz的发射频率的亚谐波（SH）流成像的可行性。本文建立在这些结果的基础上，通过检查作为传输压力的函数的SH流成像的性能。此外，我们还研究了SH脉冲波多普勒（PWD）成像的可行性。使用超声造影剂Depletion（TM）和20 MHz的成像频率，用1 mm直径的无壁血管冷冻凝胶体模进行体外流动实验。体模结果表明，有一个可识别的压力范围，在该范围内，可以使用10 MHz（SH 10）的SH成像进行准确的流速和功率估计，高于该范围，速度估计会因辐射力效应和不稳定的气泡行为而发生偏差，低于该范围，速度和功率估计会因SNR差而降低。SH PWD的体内验证在兔耳的小动脉中进行，并且血流速度估计与基本（F20）模式PWD相比良好。使用SH信号抑制组织信号的能力可以使得能够使用更高的帧速率，并且通过减少或消除对杂波滤波器的需要来提高对微血管流或大血管壁附近的慢速度的灵敏度。（电子邮件：aneedles@visualsonics.com）（C）2008年世界医学和生物学超声联合会。
A recent study has shown the feasibility of subharmonic (SH) flow imaging at a transmit frequency of 20 MHz. This paper builds on these results by examining the performance of SH flow imaging as a function of transmit pressure. Further, we also investigate the feasibility of SH pulsed-wave Doppler (PWD) imaging. In vitro flow experiments were performed with a 1-mm-diameter wall-less vessel cryogel phantom using the ultrasound contrast agent Definity(TM) and an imaging frequency of 20 MHz. The phantom results show that there is an identifiable pressure range where accurate flow velocity and power estimates can be made with SH imaging at 10 MHz (SH10), above which velocity estimates are biased by radiation force effects and unstable bubble behavior, and below which velocity and power estimates are degraded by poor SNR. In vivo validation of SH PWD was performed in an arteriole of a rabbit ear, and blood velocity estimates compared well with fundamental (F20) mode PWD. The ability to suppress tissue signals using SH signals may enable the use of higher frame rates and improve sensitivity to microvascular flow or slow velocities near large vessel walls by reducing or eliminating the need for clutter filters. (E-mail: aneedles@visualsonics.com) (C) 2008 World Federation for Ultrasound in Medicine & Biology.