Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
IEEE Trans Biomed Eng. 2012 Jan;59(1):248-54. doi: 10.1109/TBME.2011.2171341. Epub 2011 Oct 13.
Vibroacoustography (VA) is an ultrasound-based modality sensitive to stiffness and free from speckle and possesses some advantages over conventional ultrasound imaging in terms of image quality. The primary objective here is to show its feasibility in detecting/imaging kidney stones (KSs) in vitro . In VA, two intersecting ultrasound beams driven at two different frequencies f (1) and f (2), respectively, are focused within a freshly excised porcine kidney attached to a solid frame with elastic rubber bands, while the amplitude of the acoustic emission pressure field produced at the difference frequency Δf = | f(1) - f(2) | is detected by a low-frequency hydrophone. The received low-frequency signal is bandpass filtered and amplified, then digitized by a 14-bits/sample digitizer. The data are then recorded on a computer and processed numerically to construct the images. 2-D magnitude VA images are obtained at different depths within the kidney before and after stone implantation, showing kidney features and stones shapes. Experiments conducted in a water tank on a chalk sphere as well as a series of excised kidneys in which stones are artificially embedded show that all the implanted stones are detected at all chosen depths, when compared with an X-ray fluoroscopy taken to be the reference image. The resulting VA images, obtained from a nonionizing type of radiation (i.e., ultrasound waves) as compared to fluoroscopy, are speckle free unlike conventional ultrasound images. The results presented in this preliminary feasibility study show that VA allows imaging KSs in vitro, and provide the impetus to further develop and investigate VA imaging in a clinical setting for in vivo applications.
声触诊组织量化技术（VA）是一种基于超声的技术，对组织的硬度敏感，不受斑点的影响，在图像质量方面优于传统超声成像。本研究的主要目的是体外展示其检测/成像肾结石（KSs）的可行性。在 VA 中，两个相互垂直的超声束以两个不同的频率 f(1)和 f(2)驱动，分别聚焦在附着在刚性框架上的新鲜切除的猪肾内，同时通过低频水听器检测在差频Δf=|f(1)-f(2)|处产生的声发射压力场的幅度。接收的低频信号通过带通滤波器进行滤波和放大，然后由 14 位/样本的模数转换器进行数字化。数据记录在计算机上并进行数值处理以构建图像。在结石植入前后，在肾内不同深度获得 2-D 幅度 VA 图像，显示肾特征和结石形状。在水箱中的白垩球以及一系列切除的肾脏中的实验中，这些肾脏中的结石是人为嵌入的，结果表明，与 X 射线透视作为参考图像相比，所有植入的结石都在所有选定的深度被检测到。与透视相比，VA 获得的图像来自非电离类型的辐射（即超声波），与传统超声图像不同，没有斑点。这项初步可行性研究的结果表明，VA 允许在体外成像 KSs，并为进一步开发和研究 VA 成像在体内应用的临床环境提供了动力。
